Scientific Opinion on Dietary Reference Values for protein

EFSA Journal 20xx; xx:xx

Suggested citation: EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA); Scientific Opinion on Dietary

Reference Values for protein released for public consultation. EFSA Journal 20xx; xxx [63 pp.].

doi:10.2903/j.efsa.20NN.NNNN. Available online: www.efsa.europa.eu/efsajournal

DRAFT SCIENTIFIC OPINION 1

Scientific Opinion on Dietary Reference Values for protein

EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA)

2, 3

European Food Safety Authority (EFSA), Parma, Italy 4

ABSTRACT 5

This opinion of the EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA) deals with the setting of 6

Dietary Reference Values (DRVs) for protein. The Panel concludes that a Population Reference Intake (PRI) for 7

protein can be derived for adults, infants and children, and pregnant and lactating women based on nitrogen 8

balance studies. The Panel also considered several health outcomes that may be associated with protein intake, 9

but the available data were considered insufficient to establish DRVs. For adults, the Panel accepted the value of 10

0.66 g protein/kg body weight per day based on a meta-analysis of nitrogen balance data as the average 11

requirement (AR). In healthy adults, the protein requirement per kg body weight is considered to be the same for 12

both sexes and for all body weights. Considering the 97.5

percentile of the population distribution of the 13

requirement and assuming an efficiency of utilisation of dietary protein for maintenance of body protein of 47 %, 14

the PRI for adults of all ages was estimated to be 0.83 g protein/kg body weight per day. This PRI is applicable 15

both to high quality protein and to protein in mixed diets. For infants from six months, children and adolescents 16

a factorial approach as proposed by WHO/FAO/UNU (2007) was accepted. For this, protein requirements for 17

growth were estimated from average daily rates of protein deposition, assuming an efficiency of utilisation of 18

dietary protein for growth of 58 %. To these age-dependent protein requirements for growth the protein 19

requirement for maintenance of 0.66 g protein/kg body weight per day was added. For pregnant women, a 20

protein intake of 1, 9 and 28 g/d in the first, second and third trimesters, respectively, is proposed in addition to 21

the PRI for non-pregnant women. For lactating women, a protein intake of 19 g/d during the first six months of 22

lactation, and of 13 g/d after six months, is proposed in addition to the PRI for non-lactating women. The 23

available data are not sufficient to establish a Tolerable Upper Intake Level (UL) for protein. Intakes up to twice 24

the PRI are regularly consumed from mixed diets by some physically active and healthy adults in Europe and are 25

considered safe. 26

EY WORDS 27

Protein, amino acids, nitrogen balance, maintenance, growth, factorial method, efficiency of utilisation, 28

digestibility, muscle mass, body weight, obesity, insulin sensitivity, bone mineral density, kidney function, urea 29

cycle. 30

On request from the European Commission, Question No EFSA-Q-2008-468, endorsed for public consultation on 13 May

2011.

Panel members: Carlo Agostoni, Jean-Louis Bresson, Susan Fairweather-Tait, Albert Flynn, Ines Golly, Hannu Korhonen,

Pagona Lagiou, Martinus Løvik, Rosangela Marchelli, Ambroise Martin, Bevan Moseley, Monika Neuhäuser-Berthold,

Hildegard Przyrembel, Seppo Salminen, Yolanda Sanz, Sean (J.J.) Strain, Stephan Strobel, Inge Tetens, Daniel Tomé,

Hendrik van Loveren and Hans Verhagen. Correspondence: [email protected].eu

Acknowledgement: The Panel wishes to thank for the preparatory work on this Opinion: Carlo Agostoni, Jean-Louis

Bresson, Susan Fairweather-Tait, Albert Flynn, Ambroise Martin, Monika Neuhäuser-Berthold, Hildegard Przyrembel,

Sean (J.J.) Strain, Inge Tetens, Daniel Tomé.

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SUMMARY 32

Following a request from the European Commission, the EFSA Panel on Dietetic Products, Nutrition 33

and Allergies (NDA) was asked to deliver a scientific opinion on Population Reference Intakes for the 34

European population on energy and macronutrients, including protein. 35

Dietary proteins are the source of the nitrogen and indispensable amino acids which the body requires 36

for tissue growth and maintenance. The main pathway of amino acid metabolism is protein synthesis. 37

In this opinion, “protein” is total N x 6.25, and protein requirements are based on nitrogen content. 38

Protein digestion takes place in the stomach and in the small intestine. In healthy humans, the 39

absorption and transport of amino acids is usually not limited by the availability of digestive enzymes 40

or transport mechanisms, but some protein escapes digestion in the small intestine and is degraded in 41

the colon through bacterial proteolysis and amino acid catabolism. By the time digesta are excreted as 42

faeces, they consist largely of microbial protein. Therefore, when assessing protein digestibility, it is 43

important to distinguish between faecal and ileal digestibility, as well as apparent, and true, nitrogen 44

and amino acid digestibility. 45

The concept of protein requirement includes both total nitrogen and indispensable amino acid 46

requirements. The quantity and utilisation of indispensable amino acids is considered to be an 47

indicator of dietary protein quality, which is usually assessed using the Protein Digestibility-Corrected 48

Amino Acid Score (PD-CAAS). It is important to determine to what extent the nitrogen from dietary 49

protein is retained in the body. Different values for the efficiency of protein utilisation have been 50

observed for maintenance of body protein and for tissue deposition/growth; at maintenance, the 51

efficiency of nitrogen utilisation for retention is about 47 % in healthy adults who are in nitrogen 52

balance and on mixed diets. 53

The main dietary sources of proteins of animal origin are meat, fish, eggs, milk and milk products. 54

Cereal grains, leguminous vegetables, and nuts are the main dietary sources of plant proteins. Most of 55

the animal sources are considered high quality protein since they are high in indispensable amino 56

acids, whereas the indispensable amino acid content of plant proteins is usually lower. 57

Data from dietary surveys show that the average protein intake in European countries varies between 58

72 to 108 g/d in adult men and 56 to 82 g/d in adult women, or about 13 to 20 % of total energy intake 59

(E %) for both sexes. Few data are available for the mean protein intake on a body weight basis, which 60

varies from 0.8 to 1.2 g/kg bw per day for adults. 61

In order to derive Dietary Reference Values (DRVs) for protein the Panel decided to use the nitrogen 62

balance approach to determine protein requirements. Nitrogen balance is the difference between 63

nitrogen intake and the amount lost in urine, faeces, skin and other routes. In healthy adults who are in 64

energy balance the protein requirement (maintenance requirement) is defined as the amount of dietary 65

protein which is sufficient to achieve zero nitrogen balance. The dietary protein requirement is 66

considered to be the amount needed to replace obligatory nitrogen losses, after adjustment for the 67

efficiency of dietary protein utilisation and the quality of the dietary protein. The factorial method is 68

used to calculate protein requirements for physiological conditions such as growth, pregnancy or 69

lactation in which nitrogen is not only needed for maintenance but also for the deposition of protein in 70

newly formed tissue or secretions (i.e. milk). 71

According to a meta-analysis of available nitrogen balance data as a function of nitrogen intake in 72

healthy adults, the best estimate of average requirement for healthy adults was 105 mg N/kg body 73

weight per day (0.66 g high quality protein/kg per day). The 97.5

percentile was estimated as 74

133 mg N/kg body weight per day (0.83 g high quality protein/kg per day) from the distribution of the 75

log of the requirement, with a CV of about 12 %. The Panel considers that the value of 0.66 g/kg body 76

weight per day can be accepted as the Average Requirement (AR), and the value of 0.83 g/kg body 77

weight per day as the Population Reference Intake (PRI), derived for proteins with a PD-CAAS value 78

of 1.0. This value can be applied to usual mixed diets in Europe which are unlikely to be limiting in 79

their content of indispensable amino acids. For older adults, the protein requirement is equal to that for 80

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EFSA Journal 20xx;xxxx 3

adults. The lower energy requirement of sedentary elderly people means that the protein to energy 81

ratio of their requirement may be higher than for younger age groups. 82

For infants, children and adolescents, the Panel accepted the approach of WHO/FAO/UNU (2007) in 83

which estimates of the protein requirements from six months to adulthood were derived factorially as 84

the sum of requirements for maintenance and growth corrected for efficiency of utilisation. An 85

average maintenance value of 0.66 g protein/kg body weight per day was applied. Average daily needs 86

for dietary protein for growth were estimated from average daily rates of protein deposition, calculated 87

from studies on whole-body potassium deposition, and considering an efficiency of utilisation of 88

dietary protein for growth of 58 %. The PRI was estimated based on the average requirement plus 89

1.96 SD using a combined SD for growth and maintenance. 90

For pregnant women, the Panel accepted the factorial approach for deriving protein requirements 91

during pregnancy, which was based on the newly deposited protein in the foetus and maternal tissue, 92

and the maintenance requirement associated with the increased body weight. Because of the paucity of 93

data in pregnant women, and because it is unlikely that the efficiency of protein utilisation decreases 94

during pregnancy, the efficiency of protein utilisation was taken to be 47 % as in non-pregnant 95

women. Thus, for pregnant women, a PRI for protein of 1, 9 and 28 g/d in the first, second and third 96

trimesters, respectively, is proposed in addition to the PRI for non-pregnant women. 97

For lactation, the Panel accepted the factorial approach which requires assessing milk volume 98

produced and its content of both protein nitrogen and non-protein nitrogen, and calculating the amount 99

of dietary protein needed for milk protein production. As the efficiency of protein utilisation for milk 100

protein production is unknown, the same efficiency as in the non-lactating adult (47 %) was assumed. 101

The PRI was estimated by adding 1.96 SD to give an additional 19 g protein/d during the first 102

six months of lactation (exclusive breastfeeding), and 13 g protein/d after six months (partial 103

breastfeeding). 104

The Panel also considered several health outcomes that may be associated with protein intake. The 105

available data on the effects of an additional dietary protein intake beyond the PRI on muscle mass 106

and function, on body weight control and obesity (risk) in children and adults, and on insulin 107

sensitivity and glucose homeostasis do not provide evidence that can be considered as a criterion for 108

determining DRVs for protein. Likewise, the available evidence does not permit the conclusion that an 109

additional protein intake might affect bone mineral density and could be used as a criterion for the 110

setting of DRVs for protein. 111

Data from food consumption surveys show that actual mean protein intakes of adults in Europe are at, 112

or more often above, the PRI of 0.83 g/kg body weight per day. In Europe, adult protein intakes at the 113

upper end (90-97.5

percentile) of the intake distributions have been reported to be between 17 and 114

25 E%. The available data are not sufficient to establish a Tolerable Upper Intake Level (UL) for 115

protein. In adults an intake of twice the PRI is considered safe. 116

DRVs have not been derived for indispensable amino acids, since amino acids are not provided as 117

individual nutrients but in the form of protein. In addition, the Panel notes that more data are needed to 118

obtain sufficiently precise values for indispensable amino acid requirements. 119

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EFSA Journal 20xx;xxxx 4

TABLE OF CONTENTS 120

Abstract ................................................................................................................................. ..................... ........ 1121

Summary ........................................................................................................................... ......................... ........ 2122

Table of contents .......................................................................................................................... ...................... 4 123

Background as provided by the European Commission ..................................................................................... 6 124

Terms of reference as provided by European Commission ................................................................................ 6 125

Assessment ........................................................................................................................ ......................... ........ 8126

1. Introduction ..................................................................................................................... ...................... 8 127

2. Definition/category ................................................................................................................. ............... 8128

2.1. Definition ........................................................................................................................... ............... 8129

2.2. Protein digestion and metabolism ..................................................................................................... 9130

2.2.1. Intestinal protein digestion and amino acid absorption ................................................................ 9131

2.2.2. Protein turnover, amino acid metabolism and amino acid losses ............................................... 10132

2.3. Protein quality from digestibility and indispensable amino acid composition ............................... 10133

2.3.1. Measurement of protein digestibility .......................................................................................... 10134

2.3.2. The indispensable amino acid scoring method ........................................................................... 11135

2.4. Nitrogen retention and efficiency of dietary protein utilisation ...................................................... 11136

3. Dietary protein sources and intake data ............................................................................................... 12137

3.1. Nitrogen and protein content in foodstuffs – the nitrogen conversion factor ................................. 12138

3.2. Dietary sources ................................................................................................................................ 13139

3.3.

Dietary intake .................................................................................................................................. 14140

4. Overview of dietary reference values and recommendations .............................................................. 14141

4.1. Dietary reference values for protein for adults................................................................................ 14142

4.1.1. Older adults ................................................................................................................................. 15143

4.2. Dietary reference values for protein for infants and children ......................................................... 16144

4.3. Dietary reference values for protein during pregnancy ................................................................... 18145

4.4. Dietary reference values for protein during lactation ...................................................................... 18146

4.5. Requirements for indispensable amino acids .................................................................................. 19147

5. Criteria (endpoints) on which to base dietary reference values (DRVs) ............................................. 20148

5.1. Protein intake and protein and nitrogen homeostasis ...................................................................... 20149

5.1.1. Methods for the determination of protein requirement ............................................................... 20150

5.1.1.1. Nitrogen balance ................................................................................................................ 20151

5.1.1.2. The factorial method .......................................................................................................... 21152

5.1.1.3. Protein quality and reference pattern for indispensable amino acids ................................. 22153

5.1.2. Protein requirement of adults ...................................................................................................... 22154

5.1.2.1. Older adults ........................................................................................................................ 23155

5.1.3. Protein requirement of infants and children ............................................................................... 23156

5.1.4. Protein requirement during pregnancy ....................................................................................... 24157

5.1.5.

Protein requirement during lactation .......................................................................................... 25158

5.2. Protein intake and health consequences .......................................................................................... 25159

5.2.1. Muscle mass................................................................................................................................ 25160

5.2.2. Body weight control and obesity ................................................................................................ 26161

5.2.2.1. Infants ................................................................................................................................ 26162

5.2.2.2. Adults ............................................................................................................................... .. 27163

5.2.3. Insulin sensitivity and glucose control ........................................................................................ 27164

5.2.4. Bone health ................................................................................................................................. 27165

5.2.5. Kidney function .......................................................................................................................... 28166

5.2.6. Capacity of the urea cycle ........................................................................................................... 28167

5.2.7. Tolerance of protein .................................................................................................................... 29168

6. Data on which to base dietary reference values (DRVs) ..................................................................... 29169

6.1. Protein requirement of adults .......................................................................................................... 29170

6.1.1. Protein requirement of older adults ............................................................................................ 29171

6.2. Protein requirement of infants and children .................................................................................... 29172

6.3. Protein requirement during pregnancy ............................................................................................ 30173

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6.4. Protein requirement during lactation ............................................................................................... 30174

6.5. Safety of protein intakes above the PRI .......................................................................................... 30175

Conclusions ......................................................................................................................................... ............. 31176

References ...................................................................................................................... ................................ .. 32177

Appendices ....................................................................................................................................................... 45178

Appendix 1a: Population, methods and period of dietary assessment in children and adolescents in European 179

countries ....................................................................................................................................... .................... 45180

Appendix 1b: Intake of protein among children aged ~1-3 years in European countries ................................ 47181

Appendix 1c: Intake of protein among children aged ~4-6 years in European countries ................................. 48182

Appendix 1d: Intake of protein among children aged ~7-9 years in European countries ................................ 49183

Appendix 1e: Intake of protein among children aged ~10-14 years and over in European countries .............. 50184

Appendix 1f: Intake of protein among adolescents aged ~15-18 years and over in European countries ......... 51185

Appendix 2a: Population, methods and period of dietary assessment in adults in European countries ........... 52186

Appendix 2b: Intake of protein among adults aged ~19-65 years in European countries ................................ 55187

Appendix 2c: Intake of protein among adults aged ~19-34 years in European countries ................................ 56188

Appendix 2d: Intake of protein among adults aged ~35-64 years in European countries ................................ 57189

Appendix 2e: Intake of protein among adults aged ~65 years and over in European countries ....................... 58190

Appendix 3: Calculation of PRI for infants, children and adolescents ............................................................. 59191

Glossary/Abbreviations .................................................................................................................................... 60192

193

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BACKGROUND AS PROVIDED BY THE EUROPEAN COMMISSION 194

The scientific advice on nutrient intakes is important as the basis of Community action in the field of 195

nutrition, for example such advice has in the past been used as the basis of nutrition labelling. The Scientific 196

Committee for Food (SCF) report on nutrient and energy intakes for the European Community dates from 197

1993. There is a need to review and if necessary to update these earlier recommendations to ensure that the 198

Community action in the area of nutrition is underpinned by the latest scientific advice. 199

In 1993, the SCF adopted an opinion on the nutrient and energy intakes for the European Community

. The 200

report provided Reference Intakes for energy, certain macronutrients and micronutrients, but it did not 201

include certain substances of physiological importance, for example dietary fibre. 202

Since then new scientific data have become available for some of the nutrients, and scientific advisory bodies 203

in many European Union Member States and in the United States have reported on recommended dietary 204

intakes. For a number of nutrients these newly established (national) recommendations differ from the 205

reference intakes in the SCF (1993) report. Although there is considerable consensus between these newly 206

derived (national) recommendations, differing opinions remain on some of the recommendations. Therefore, 207

there is a need to review the existing EU Reference Intakes in the light of new scientific evidence, and taking 208

into account the more recently reported national recommendations. There is also a need to include dietary 209

components that were not covered in the SCF opinion of 1993, such as dietary fibre, and to consider whether 210

it might be appropriate to establish reference intakes for other (essential) substances with a physiological 211

effect. 212

In this context the EFSA is requested to consider the existing Population Reference Intakes for energy, 213

micro- and macronutrients and certain other dietary components, to review and complete the SCF 214

recommendations, in the light of new evidence, and in addition advise on a Population Reference Intake for 215

dietary fibre. 216

For communication of nutrition and healthy eating messages to the public it is generally more appropriate to 217

express recommendations for the intake of individual nutrients or substances in food-based terms. In this 218

context the EFSA is asked to provide assistance on the translation of nutrient based recommendations for a 219

healthy diet into food based recommendations intended for the population as a whole. 220

ERMS OF REFERENCE AS PROVIDED BY EUROPEAN COMMISSION 221

In accordance with Article 29 (1)(a) and Article 31 of Regulation (EC) No. 178/2002, the Commission 222

requests EFSA to review the existing advice of the Scientific Committee for Food on Population Reference 223

Intakes for energy, nutrients and other substances with a nutritional or physiological effect in the context of a 224

balanced diet which, when part of an overall healthy lifestyle, contribute to good health through optimal 225

nutrition. 226

In the first instance the EFSA is asked to provide advice on energy, macronutrients and dietary fibre. 227

Specifically advice is requested on the following dietary components: 228

• Carbohydrates, including sugars; 229

• Fats, including saturated fatty acids, poly-unsaturated fatty acids and mono-unsaturated fatty acids, 230

trans fatty acids; 231

• Protein; 232

• Dietary fibre. 233

Scientific Committee for Food, Nutrient and energy intakes for the European Community, Reports of the Scientific Committee for

Food 31st series, Office for Official Publication of the European Communities, Luxembourg, 1993.

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EFSA Journal 20xx;xxxx 7

Following on from the first part of the task, the EFSA is asked to advise on Population Reference Intakes of 234

micronutrients in the diet and, if considered appropriate, other essential substances with a nutritional or 235

physiological effect in the context of a balanced diet which, when part of an overall healthy lifestyle, 236

contribute to good health through optimal nutrition. 237

Finally, the EFSA is asked to provide guidance on the translation of nutrient based dietary advice into 238

guidance, intended for the European population as a whole, on the contribution of different foods or 239

categories of foods to an overall diet that would help to maintain good health through optimal nutrition 240

(food-based dietary guidelines). 241

242

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ASSESSMENT 243

1. Introduction 244

Dietary proteins are an essential component of the diet by virtue of supplying the body with nitrogen (N) and 245

amino acids which are used to synthesise and maintain the around 25,000 proteins encoded within the human 246

genome as well as other non protein metabolically active nitrogenous substances like peptide hormones, 247

neurotransmitters, nucleic acids, glutathione or creatine. In addition, amino acids are also subjected to 248

deamination, and their carbon skeleton is used in different metabolic pathways or as energy substrate. 249

2. Definition/category 250

2.1. Definition 251

Proteins are built from amino acids joined together by peptide bonds between the carboxyl group and the 252

amino (or imino in the case of proline) group of the next amino acid in line. These polypeptide chains are 253

folded into a three dimensional structure to form the protein. The primary structure or sequence of amino 254

acids in proteins is pre-determined in the genetic code. Twenty of the naturally occurring amino acids are so-255

called proteinogenic amino acids, which build proteins in living organisms. With few exceptions, only 256

L-isomers are incorporated into proteins. 257

Dietary proteins are the source of nitrogen and indispensable amino acids for the body. Both in the diet and 258

in the body, 95 % of the nitrogen is found in the form of proteins and 5 % is found in the form of other 259

nitrogenous compounds, i.e. free amino acids, urea or nucleotides. A conversion factor of 6.25 for the 260

conversion of nitrogen to protein is usually used for labelling purposes, assessment of protein intake and for 261

protein reference values. Total N x 6.25 is called crude protein and [total minus non-protein-N] x 6.25 is 262

called true protein. For other purposes, protein specific nitrogen conversion factors can be used (see 263

section 3.1). In this opinion, unless specifically mentioned, “protein” is total N x 6.25, and protein 264

requirements are calculated from nitrogen content. 265

The 20 proteinogenic amino acids are classified as indispensable or dispensable amino acids. Nine amino 266

acids are classified as indispensable in humans (histidine, isoleucine, leucine, lysine, methionine, 267

phenylalanine, threonine, tryptophan and valine) as they cannot be synthesised in the human body from 268

naturally occurring precursors at a rate to meet the metabolic requirement. The remaining dietary amino 269

acids are dispensable (alanine, arginine, cysteine, glutamine, glycine, proline, tyrosine, aspartic acid, 270

asparagine, glutamic acid and serine). Among the nine indispensable amino acids, lysine and threonine are 271

strictly indispensable since they are not transaminated and their deamination is irreversible. In contrast, the 272

seven other indispensable amino acids can participate in transamination reactions. In addition, some of the 273

dispensable amino acids which under normal physiological conditions can be synthesised in the body, can 274

become limiting under special physiological or pathological conditions, such as in premature neonates when 275

the metabolic requirement cannot be met unless these amino acids are supplied in adequate amounts with the 276

diet; they are then called conditionally indispensable amino acids (arginine, cysteine, glutamine, glycine, 277

proline, tyrosine) (IoM, 2005; NNR, 2004). 278

Besides being a building block for protein synthesis, each amino acid has its own non-proteogenic metabolic 279

pathways. Some amino acids are used as precursors for nitrogenous compounds such as glutathione, various 280

neurotransmitters, nitrogen monoxide, creatine, carnitine, taurine or niacin. Glutamine, aspartate and glycine 281

are used for the synthesis of ribo- and desoxyribonucleotides, precursors for the synthesis of the nucleic acids 282

RNA and DNA. Arginine and glutamine are precursors of non-proteinogenic amino acids including ornithine 283

and citrulline that play a role in inter-organ exchange of nitrogen. Glutamine and glutamate are precursors of 284

Krebs cycle components and are also important energy substrates for various cells. Amino acids are used 285

after deamination as energy substrates, and in gluconeogenesis and ketogenesis. Some of the amino acids can 286

also act directly or indirectly as intracellular signal molecules. Glutamate is a well known neurotransmitter, 287

tryptophan is the precursor of serotonin, tyrosine is the precursor of catecholamines and dopamine, as well as 288

of thyroid hormones, and histidine is the precursor of histamine. Arginine is an activator of the first step of 289

/NH

elimination in the hepatic urea cycle, acts as a secretagogue for β-cells of pancreatic Langerhans 290

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EFSA Journal 20xx;xxxx 9

islets, and is - via nitric oxide synthase activity - the precursor of nitrogen monoxide that regulates blood 291

pressure. Lastly, leucine has been subjected to numerous studies for its role as a signal for protein synthesis 292

via the mTOR (mammalian target of rapamycin) signalling pathway. These non-proteogenic metabolic 293

pathways and signalling activities are included in the concept of protein requirement when nitrogen balance 294

is achieved and indispensable amino acid requirements are met. As a consequence, they are not used as 295

additional markers for the determination of protein requirement. 296

2.2. Protein digestion and metabolism 297

Protein metabolism comprises the processes that regulate protein digestion, amino acid metabolism and body 298

protein turnover. These processes include the absorption and supply of both dispensable and indispensable 299

dietary amino acids, the de novo synthesis of dispensable amino acids, protein hydrolysis, protein synthesis 300

and amino acid utilisation in catabolic pathways or as precursors for nitrogenous components. 301

2.2.1. Intestinal protein digestion and amino acid absorption 302

The fluxes of nitrogen, amino acids and protein in the gut exhibit a relatively complex pattern. In humans, 303

ingested dietary proteins (about 40–110 g/d), endogenous protein secreted into the gut (20–50 g/d), and 304

molecules containing non-protein nitrogen (urea and other molecules) secreted into the gut are mixed in the 305

lumen of the stomach and the small intestine, and are subjected to transit, digestion and absorption 306

(Gaudichon et al., 2002). The majority is transferred into the body by absorption across the intestinal mucosa 307

whereas a smaller part remains in the lumen and reaches the terminal ileum. This, along with other 308

undigested luminal components, passes from the terminal ileum into the large intestine, where it is all 309

subjected to fermentation by the microflora. 310

Protein digestion starts in the stomach and is continued in the small intestine. In healthy humans, digestive 311

enzymes and transport across the brush border membrane via a variety of transporters are not a limiting 312

factor for amino acid absorption (Johnson et al., 2006). The metabolic activity of the small intestine is high, 313

and the small intestinal mucosa metabolises a significant proportion of both dispensable and indispensable 314

amino acids in the course of absorption. In the absorptive state, dietary rather than systemic amino acids are 315

the major precursors for mucosal protein synthesis. Glutamine and glutamate, which are the most important 316

fuels for intestinal tissue, are mostly used by the intestine, and their appearance in the portal circulation is 317

usually very low. Fifty to sixty percent of threonine is used by the intestine mainly for mucin synthesis by 318

goblet cells. Of the amino acids lysine, leucine or phenylalanine, 15-30 % is used by the intestine whereas 319

the other fraction appears in the portal circulation. Catabolism dominates the intestinal utilisation of dietary 320

amino acids, since only 12 % of the amino acids extracted by the intestine are used for mucosal protein 321

synthesis. 322

Approximately 15 g protein/d remains in the intestinal lumen and enters the colon. There it is degraded into 323

peptides and amino acids through bacterial proteolysis, and amino acids are further deaminated and 324

decarboxylated. This process is considered to be a major pathway for amino acid losses at maintenance

325

intake of dietary protein (Gaudichon et al., 2002). The microflora possesses ureolytic activity so that urea 326

nitrogen secreted into the intestine can be recycled both by microbial amino acid synthesis and by the uptake 327

of ammonia from the gut. The ammonia is predominantly incorporated into alanine, aspartate/asparagine and 328

glutamate/glutamine from which it may be incorporated into most of the amino acids by transamination. This 329

mechanism of urea recycling might be of value in conserving nitrogen (Fouillet et al., 2008; Jackson, 1995). 330

As a consequence of the activities of the intestinal microbiota, by the time digesta are excreted as faeces their 331

protein content is largely of microbial origin. Therefore, faecal or ileal digestibility measurements, as well as 332

apparent and true nitrogen and amino acid digestibility measurements (see section 2.3.1.), have very different 333

significance and can be used for different objectives. Measurements at the ileal level are critical for 334

determining amino acid losses of both dietary and endogenous origin, whereas measurements at the faecal 335

level are critical in assessing whole-body nitrogen losses (Fuller and Tome, 2005). The impact of the 336

recycling of intestinal nitrogen, and of amino acids synthesised by bacteria, on whole body requirement of 337

nitrogen, amino acids and protein is not clear. Other bacteria-derived amino acid metabolites include short 338

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EFSA Journal 20xx;xxxx 10

chain fatty acids, sulphides, ammonia, phenols or indoles. The health consequences of changes in the luminal 339

concentration of these products have not been extensively studied. 340

2.2.2. Protein turnover, amino acid metabolism and amino acid losses 341

The main pathway of amino acid metabolism is protein synthesis. In a 70 kg adult man, the body protein 342

pool represents 10-12 kg, of which 42 % is in skeletal muscle, 15 % each in skin and blood, and 10 % in 343

visceral organs. Four proteins (collagen, myosin, actin and haemoglobin) account for half of the body protein 344

pool, and 25 % of the proteins of the body are present as collagen. The 12 kg body protein pool is in 345

continuous turnover and exchanges with the free amino acid pool, which is approximately 100 g, via the 346

proteosynthesis and proteolysis pathways at a rate of 250-300 g/d in a 70 kg adult man (Waterlow, 1995, 347

1996). This protein turnover is 2-3 times higher than the usual dietary protein intake (NNR, 2004). 348

Moreover, the synthesis and turnover rates vary between the different body proteins. Visceral tissues have a 349

fast protein turnover whereas peripheral tissues have a lower rate. 350

Amino acids are irreversibly lost in the faeces (25-30 % of total amino acid losses), by metabolic oxidation 351

(70-75 % of total amino acid losses) and as miscellaneous losses in urine (about 0.6 g amino acids or 40 mg 352

nitrogen in male adults), hair, skin, bronchial and other secretions, and in lactating women as milk (SCF, 353

1993). These amino acid losses need to be balanced by the supply of dietary protein-derived amino acids 354

(50-100 g/d). When protein intake is increased the metabolic oxidative losses are also increased in order to 355

achieve amino acid and nitrogen balance (Forslund et al., 1998; Morens et al., 2003; Pacy et al., 1994; Price 356

et al., 1994)

. 357

2.3. Protein quality from digestibility and indispensable amino acid composition 358

The nutritional value of dietary proteins is related to their ability to satisfy nitrogen and amino acid 359

requirements for tissue growth and maintenance. According to current knowledge this ability mainly depends 360

on the digestibility of protein and amino acids, and on the dispensable and indispensable amino acid 361

composition of the proteins. 362

2.3.1. Measurement of protein digestibility 363

The aim of measuring protein digestibility is to predict the quantity of absorbed nitrogen or amino acids 364

following protein consumption. Though several in vitro methods requiring enzymatic hydrolysis have been 365

proposed, the classical approach uses in vivo digestibility in an animal model or in humans. The classical in 366

vivo procedure is based on faecal collection and determination of the nitrogen output over several days. 367

Apparent digestibility of protein is measured from the difference between nitrogen ingested and nitrogen 368

excreted in the faeces. It does not take into account the presence of endogenous nitrogen secretion and 369

colonic metabolism. Apparent digestibility is one component in the assessment of whole-body nitrogen 370

losses. For the determination of true (or real) digestibility, discrimination between exogenous nitrogen (food) 371

and endogenous nitrogen losses (secretions, desquamations, etc.) is needed. Individual amino acid 372

digestibility is usually related to whole protein nitrogen digestibility. Alternatively, individual amino acid 373

digestibility can be determined. 374

Both direct and indirect methods have been proposed to distinguish and quantify the endogenous and dietary 375

components of nitrogen and amino acids in ileal chyme or faeces. These approaches include the 376

administration of a protein-free diet, the enzyme-hydrolysed protein method, different levels of protein 377

intake, or multiple regression methods, in which it is assumed that the quantity and amino acid composition 378

of endogenous losses is constant and independent of diet (Baglieri et al., 1995; Fuller and Reeds, 1998; 379

Fuller and Tome, 2005). Substantial advances in the ability to discriminate between exogenous (dietary) and 380

endogenous nitrogen have been achieved using stable isotopes (Fouillet et al., 2002). By giving diets 381

containing isotopically-labelled amino acids (usually at the carbon or nitrogen atom) the endogenous flow is 382

estimated from the dilution of the isotopic enrichment in the digesta (Fouillet et al., 2002; Gaudichon et al., 383

1999; Tome and Bos, 2000). Regarding the dietary amino acid fraction, it is also questionable whether 384

protein (overall nitrogen) digestibility is a good proxy for individual ileal amino acid digestibility because 385

some studies have reported modest ranges of variation of individual amino acid digestibility around the value 386

for nitrogen digestibility (Fuller and Tome, 2005). It appeared that in some cases there are substantial 387

Dietary reference values for protein

EFSA Journal 20xx;xxxx 11

differences in true digestibility among amino acids (Fouillet et al., 2002; Gaudichon et al., 2002; Tome and 388

Bos, 2000). 389

The unabsorbed amino acids are mostly metabolised by colonic bacteria. Therefore, the apparent digestibility 390

measured in ileal effluent should be considered as a critical biological parameter for dietary amino acid 391

digestibility (Fuller and Tome, 2005). Digestibility values obtained by the faecal analysis method usually 392

overestimate those obtained by the ileal analysis method. In humans, intestinal effluents for the estimation of 393

apparent digestibility are obtained either from ileostomy patients or, preferably, in healthy volunteers by 394

using naso-intestinal tubes. These approaches are not, however, straightforward, and are too demanding for 395

routine evaluation of food, but can be used as reference methods (Fouillet et al., 2002; Fuller et al., 1994). 396

An alternative is the use of animal models, most commonly the rat and the pig. The rat is used for the 397

determination of protein quality in human diets (FAO/WHO, 1991). However, some differences in protein 398

digestibility have been observed between rats, pigs and humans (Fuller and Tome, 2005). 399

The usefulness of the values obtained by digestibility measurements depends on the objective. In vitro 400

digestibility measurements can only be used to compare products with one another, and can never serve as 401

independent reference values. Measurement of apparent and real digestibility is critical for determining 402

amino acid losses of both dietary and endogenous origin. Data in humans are preferred whenever possible. 403

The determination of individual amino acid digestibility is also preferred whenever possible. A 404

complementary and still unresolved aspect of digestibility assessments is how to take into account the 405

recycling of intestinal nitrogen and bacterial amino acids in the body. 406

2.3.2. The indispensable amino acid scoring method 407

The concept of protein requirement includes both total nitrogen and indispensable amino acids requirements. 408

Therefore, the content and utilisation of indispensable amino acids can be considered as valuable criteria for 409

the evaluation of dietary protein quality (WHO/FAO/UNU, 2007). This idea leads to the use of the amino 410

acid scoring approach in which the indispensable amino acid composition of the dietary protein is compared 411

to a reference pattern of indispensable amino acids which is assumed to meet requirements for indispensable 412

amino acids at a protein supply which corresponds to the average protein requirement. The reference pattern 413

of indispensable amino acids is derived from measurements of the indispensable amino acid requirements 414

(WHO/FAO/UNU, 2007) (see section 4.5). Originally, the chemical score was based on the complete 415

analysis of the food amino acid content and its comparison to the amino acid pattern of a chosen reference 416

protein (e.g. egg or milk protein). 417

In the traditional scoring method, the ratio between the content in a protein and the content in the reference 418

pattern is determined for each indispensable amino acid. The lowest value is used as the score. The Protein 419

Digestibility-Corrected Amino Acid Score (PD-CAAS) corrects the amino acid score by the digestibility of 420

the protein (FAO/WHO, 1991) or of each individual amino acid. The accuracy of the scoring approach 421

depends on the precision of amino acid analysis and on the measurement of protein digestibility. A more 422

precise approach is to use the specific ileal digestibility of individual amino acids. The PD-CAAS can be 423

used as a criterion for the protein quality of both foods and diets. A PD-CAAS <1 indicates that at least one 424

amino acid is limiting, whereas a score ≥1 indicates that there is no limiting amino acid in the food or diet. 425

2.4. Nitrogen retention and efficiency of dietary protein utilisation 426

A traditional approach for evaluating the efficiency of protein utilisation has been to consider the interaction 427

with a physiological process such as growth. The Protein Efficiency Ratio (PER) that relates the average 428

animal (rat) weight gain to the amount of ingested protein over 28 days (AOAC, art. 43.253 to 43.257) is 429

simple, but presents several shortcomings and inaccuracies. The main difficulty lies in the significance of 430

extrapolation to humans. 431

Determination of the nutritional efficiency of protein in the diet is in most cases based on estimating the 432

extent to which dietary protein nitrogen is absorbed and retained by the organism, and is able to balance 433

daily nitrogen losses. It is determined by measuring faecal, urinary and miscellaneous nitrogen losses. Net 434

Protein Utilisation (NPU) is the percentage of ingested nitrogen that is retained in the body, and the 435

Biological Value (BV) gives the percentage of absorbed nitrogen that is retained. BV is the product of NPU 436

Dietary reference values for protein

EFSA Journal 20xx;xxxx 12

and digestibility. Similar to digestibility, NPU values are true or apparent depending on whether the loss of 437

endogenous nitrogen is taken into account or not, and this is critical to precisely determining the efficiency 438

of dietary protein utilisation and the quality of the different dietary protein sources. The true NPU can be 439

calculated as follows: 440

True NPU = total N

ingested

- [(total N

faeces

– endogenous N

faeces

)+(total N

urine

– endogenous N

urine

)]/total N

ingested

441

Endogenous intestinal (faecal) and metabolic (urinary) nitrogen losses can be obtained with a protein free 442

diet, derived from the y-intercept of the regression line relating nitrogen intake to retention at different levels 443

of protein intake, or directly determined from experiments using isotopically-labelled dietary proteins. 444

As the post-prandial phase is critical for dietary protein utilisation, the measurement of the immediate 445

retention of dietary nitrogen following meal ingestion represents a reliable approach for the assessment of 446

protein nutritional efficiency. In the net protein postprandial utilisation (NPPU) approach, true dietary 447

protein nitrogen retention is directly measured in the post-prandial phase from experiments using 448

N-labelled dietary proteins (Fouillet et al., 2002). A mean value of 70 % can be considered for the NPPU of 449

dietary proteins (Bos et al., 2005). This NPPU approach represents the maximal potential NPU efficiency of 450

the dietary protein sources when determined in optimised controlled conditions in healthy adults, and it can 451

be modified by different factors including food matrix, diet and physiological conditions. 452

From nitrogen balance studies, an NPU value of 47 % (median value, 95 % CI 44–50 %) was derived from 453

the slope of the regression line relating nitrogen intake to retention for healthy adults at maintenance, and no 454

differences were found between the results when the data were grouped by sex, diet or climate (Rand et al., 455

2003; WHO/FAO/UNU, 2007). The results suggested a possible age difference in nitrogen utilisation with a 456

lower efficiency in individuals above 55 years (31 % compared with 48 % for adults up to 55 years, 457

p=0.003), but because of the apparent interaction between age and sex in the data, the extreme variability in 458

the younger men, and the fact that the lower values for the older adults came from a single study, these 459

results were not accepted as conclusive (Rand et al., 2003). There are different values used for efficiency of 460

protein utilisation for maintenance (47 %) and for tissue deposition/growth in different populations and age 461

groups including infants and pregnant or lactating women (IoM, 2005; King et al., 1973; WHO/FAO/UNU, 462

2007). 463

The Panel considers that methods related to growth in rats (protein efficiency ratio, PER) are not reliable for 464

humans. Methods related to nitrogen retention (NPPU, NPU, BV) are preferable as they reflect more 465

accurately the protein nutritional value, and can be used as reference methods. From available data in healthy 466

adults at maintenance the mean optimal NPU value defined as NPPU is 70 %, and the usual NPU value as 467

determined from nitrogen balance studies is approximately 47 %. 468

3. Dietary protein sources and intake data 469

3.1. Nitrogen and protein content in foodstuffs – the nitrogen conversion factor 470

Assuming an average nitrogen content of 160 mg/g protein, a conversion factor of 6.25 is used for the 471

calculation of the (crude) protein content of a food from the total nitrogen content. Specific conversion 472

factors for different proteins have been proposed (Jones, 1941; Leung et al., 1968; Pellett and Young, 1980), 473

including for instance milk and milk products (6.38), other animal products (6.25), wheat (5.83) or soy 474

protein (5.71). Besides variations in the nitrogen content of different proteins, the presence or absence of a 475

non-protein fraction of the total nitrogen content of a food will influence the calculated crude protein content 476

(SCF, 2003). 477

Conversion factors based on the amino acid composition of a protein have been proposed to define more 478

accurately the true protein content of different foodstuffs (AFSSA, 2007; SCF, 2003). The choice of one or 479

several conversion factors depends on the objective, and if the aim is to indicate a product’s capacity to 480

supply nitrogen, a single coefficient is enough. However, if the objective is to indicate a product’s potential 481

to supply amino acids, the use of specific coefficients based on amino acid-derived nitrogen content is more 482

relevant. Such protein amino acid composition-derived conversion factors have been determined for different 483

Dietary reference values for protein

EFSA Journal 20xx;xxxx 13

protein sources: milk and milk products (5.85), meat, fish and eggs (5.6), wheat and legumes (5.4), and a 484

default conversion factor (5.6) (AFSSA, 2007). 485

3.2. Dietary sources 486

Dietary proteins are found in variable proportions in different foods, resulting in variability of dietary protein 487

intake within and between populations. Proteins differ in their amino acid composition and indispensable 488

amino acid content. The main dietary sources of proteins of animal origin are meat, fish, eggs, milk and milk 489

products. Most of these animal dietary protein sources have a high content in protein and indispensable 490

amino acids. Main dietary sources of plant proteins are cereal grains, leguminous vegetables and nuts. The 491

protein content differs from one plant source to another accounting for 20-30 % (w/w) for uncooked legume 492

seeds or around 10 % for cereal seeds. The indispensable amino acid content of plant proteins is usually 493

lower than that of animal proteins. In addition to the PD-CAAS, technological treatments applied to proteins 494

during extraction processes and during the production of foodstuffs may modify the characteristics and 495

properties of food proteins. 496

Examples of the range of protein content of some animal- and plant-derived foods are provided in Table 1. 497

The water and energy contents of these foods can differ greatly. 498

Table 1: Protein content (N x 6.25, g/100 g of edible food) of some animal- and plant-derived food 499

products. 500

Animal-derived foods Protein content

(N x 6.25, g/100 g)

Plant-derived foods Protein content

(N x 6.25, g/100 g)

Red meat (raw and cooked) 20-33 Vegetables 1-5

Poultry (raw and cooked) 22-37 Legumes 4-14

Fish 15-25 F

uits 0.3-2

Eggs 11-13

uts and seeds 8-29

Cheese, hard 27-34 Pasta and rice (cooked) 2-6

Cheese, soft 12-28 Breads and rolls 6-13

Milk products 2-6 Breakfast cereals 5-13

Data adapted from the ANSES/CIQUAL French food composition table version 2008, available from: 501

http://www.afssa.fr/TableCIQUAL/index.htm (ANSES/CIQUAL, 2008) 502

503

Several methods exist for assessing protein quality, for example the content of indispensable amino acids. 504

One of the food composition tables providing the most detailed amino acid profiles of various foodstuffs is 505

the table of the United States Department of Agriculture (USDA/ARS, 2009). High quality protein has an 506

optimal indispensable amino acid composition for human needs and a high digestibility. Most dietary protein 507

of animal origin (meat, fish, milk and egg) can be considered as such high quality protein. In contrast, some 508

dietary proteins of plant origin can be regarded as being of lower nutritional quality due to their low content 509

in one or several indispensable amino acids, or due to their lower digestibility. It is well established that 510

lysine is limiting in cereal protein, and that sulphur-containing amino acids (cysteine and methionine) are 511

limiting in legumes. Most of the Western diets have a PD-CAAS equal or higher than 1 because high quality 512

proteins dominate over low quality proteins. Although proteins limited in one amino acid can complement in 513

the diet proteins which are limited in another amino acid, a high level of cereal in the diet in some countries 514

can lead to a PD-CAAS lower than 1, mainly because of a low content of lysine. 515

Due to the high content of indispensable amino acids in animal proteins, a diet rich in animal protein usually 516

has a content of each indispensable amino acid above the requirement. It is widely accepted that a balance 517

between dispensable and indispensable amino acids is a more favourable metabolic situation than a 518

Dietary reference values for protein

EFSA Journal 20xx;xxxx 14

predominance of indispensable amino acids, since indispensable amino acids consumed in excess of 519

requirement are either converted to dispensable amino acids or directly oxidised. 520

3.3. Dietary intake 521

Typical intakes of (crude) protein of children and adolescents from 19 countries (Appendix 1) and of adults 522

from 22 countries in Europe are presented (Appendix 2). The data refer to individual-based food 523

consumption surveys, conducted from 1989 onwards. Most studies comprise nationally representative 524

population samples. 525

As demonstrated in the annexes, there is a large diversity in the methodology used to assess the individual 526

intakes of children, adolescents and adults. Because the different methods apply to different time frames, this 527

inevitably results in variability in both the quality and quantity of available data, which makes direct 528

comparison difficult. Moreover, age classifications are in general not uniform. Comparability is also 529

hampered by differences in the food composition tables used for the conversion of food consumption data to 530

estimated nutrient intakes (Deharveng et al., 1999). 531

Although these differences may have an impact on the accuracy of between country comparisons, the 532

presented data give a rough overview of the protein intake in a number of European countries. Most studies 533

reported mean intakes and standard deviations (SD), or mean intakes and intake distributions. In most studies 534

the contribution of protein to energy intake is based on total energy intake (including energy from alcohol). 535

In adults, average protein intake in absolute amounts ranges from approximately 72 to 108 g/d in men and 536

from 56 to 82 g/d in women. Available data suggest an average intake of 0.8 to 1.25 g/kg body weight per 537

day for adults. Average protein intake varies in infants and young children from 25 to 63 g/d. Average daily 538

intake increases with age to about 55 to 116 g/d in adolescents aged 15-18 years. In general, males have 539

higher intakes than females. Only a few countries present data per kg body weight. However, when related to 540

reported mean body weights (SCF, 1993), the estimated mean intake varies from ≥3 g/kg body weight per 541

day in the youngest age groups to approximately 1.2 to 2.0 g/kg body weight per day in children aged 10-542

18 years. 543

When expressed as % of energy intake (E%), average total protein intake ranges from about 13 to 20 E% in 544

adults, with within population ranges varying from 10-14 E% at the lower (2.5–10

percentile) to 545

17-25 E% at the upper (90-97.5

percentile) end of the intake distributions. Average intakes of 17 E% and 546

higher are observed, for example in France, Romania, Portugal and Spain. Available data show that average 547

protein intake in children and adolescents in European countries varies from 11 to 18 E%. Within population 548

ranges vary from about 6-13 E% (2.5-10

percentile) to 16-22 E% (90-97.5

percentile). 549

4. Overview of dietary reference values and recommendations 550

A number of national and international organisations and authorities have set dietary reference values 551

(DRVs) for protein and other energy-providing nutrients, as well as for dietary fibre. Generally, reference 552

intakes for protein are expressed as g/kg per day and g/d (adjusting for reference body weights), and as a 553

percentage of total energy intake (E%), and refer to high quality protein (e.g. milk and egg protein). 554

4.1. Dietary reference values for protein for adults 555

Table 2 lists the reference intakes set by various organisations for adult humans. 556

In their report, FAO/WHO/UNU (1985) used nitrogen balance to derive a population average requirement of 557

0.6 g/kg body weight per day and, adding two standard deviations (2x12.5 %) to allow for individual 558

variability, a “safe level of intake” of 0.75 g/kg body weight per day. The UK COMA (DoH, 1991) and the 559

SCF (1993) accepted the values adopted by FAO/WHO/UNU (1985). The Netherlands (Health Council of 560

the Netherlands, 2001) also used the approach of FAO/WHO/UNU (1985) but applied a CV of 15 % to allow 561

for individual variability, and derived a recommended intake of 0.8 g/kg body weight per day. The Nordic 562

Nutrition recommendations (NNR, 2004), taking account of the fact that diets in industrialised countries 563

have high protein contents, set a desirable protein intake of 15 E% for food planning purposes, with a range 564

Dietary reference values for protein

EFSA Journal 20xx;xxxx 15

of 10-20 E% for adults. This translates into protein intakes of well above 0.8 g/kg body weight per day. The 565

US Institute of Medicine recommended 0.8 g/kg body weight per day of good quality protein for adults 566

(IoM, 2005). The criterion of adequacy used for the estimated average requirement (EAR) of protein is based 567

on the lowest continuing intake of dietary protein that is sufficient to achieve body nitrogen equilibrium 568

(zero balance). 569

WHO/FAO/UNU (2007) re-evaluated their recommendations from 1985. Based on a meta-analysis of 570

nitrogen balance studies in humans by Rand et al. (2003) which involved studies stratified for a number of 571

subpopulations, settings in different climates, sex, age and protein source, a population average requirement 572

of 0.66 g/kg body weight per day resulted as the best estimate. The “safe level of intake” was identified as 573

the 97.5

percentile of the population distribution of requirement, which was equivalent to 0.83 g/kg body 574

weight per day of high quality proteins (WHO/FAO/UNU, 2007). The French recommendations (AFSSA, 575

2007) established a PRI of 0.83 g/kg body weight per day for adults based on the WHO/FAO/UNU (2007) 576

report. The German speaking countries (D-A-CH, 2008) used the average requirement for high quality 577

protein of 0.6 g/kg body weight per day (estimated by FAO/WHO (1985)), included an allowance for 578

individual variability (value increased to 0.75 g/kg body weight per day), and took account of frequently 579

reduced protein digestibility in mixed diets to establish a recommended intake of 0.8 g/kg body weight per 580

day for adults. 581

Table 2: Overview of dietary reference values for protein for adults. 582

FAO/

WHO/UNU

(1985)

DoH

(1991)

SCF

(1993)

Health Council

of the

Netherlands

(2001)

NNR

(2004)

IoM

(2005)

WHO/

FAO/UNU

(2007)

AFSSA

(2007)

D-A-CH

(2008)

AR - Adults

(g/kg bw x d

-1

)

0.60 0.60 0.60 0.60 - 0.66 0.66 0.66 0.60

PRI - Adults

(g/kg bw x d

-1

)

0.75

0.75 0.75 0.80 - 0.80

0.83

0.83 0.80

PRI - Adult

Males (g/d)

- 56 56

59 - 56 - - 59

PRI - Adult

Females (g/d)

- 45

- 46

- -

Recommended

intake range –

Adults (E%)

- - - - 10-20 10-35

- - -

Safe level of intake;

Recommended dietary allowance (RDA);

Acceptable Macronutrient Distribution Range 583

4.1.1. Older adults 584

In 1985, FAO/WHO/UNU recommended an intake of 0.75 g/kg body weight per day of good quality protein 585

for adults and the same recommendation was made for adults over the age of 60 years because, although 586

efficiency of protein utilisation is assumed to be lower in older adults, the smaller amount of lean body mass 587

per kg body weight will result in a higher figure per unit lean body mass than in younger adults 588

(FAO/WHO/UNU, 1985). 589

The recommended intake for adults in the Netherlands (Health Council of the Netherlands, 2001) is 0.8 g/kg 590

body weight per day and no additional allowance was considered necessary for adults aged >70 years. The 591

US Institute of Medicine recommended 0.8 g/kg body weight per day of good quality protein for adults 592

(IoM, 2005). For adults aged 51-70 years and >70 years, no additional protein allowance beyond that of 593

younger adults was considered necessary since no significant effect of age on protein requirement expressed 594

per kg body weight was observed in the analysis by Rand et al. (2003), recognising that lean body mass as % 595

body weight, and protein content of the body, both decrease with age. 596

Also WHO/FAO/UNU (2007) concluded that the available data did not provide convincing evidence that the 597

protein requirement of elderly people (per kg body weight, no age range given) differs from the protein 598

requirement of younger adults. The conclusion is partly supported by data on nitrogen balance (Campbell et 599

Dietary reference values for protein

EFSA Journal 20xx;xxxx 16

al., 2008) which showed that the mean protein requirement was not different between younger (21–46 years) 600

and older (63–81 years) healthy adults: 0.61 (SD 0.14) compared with 0.58 (SD 0.12) g protein/kg body 601

weight per day. However, the low energy requirement of sedentary elderly people means that the protein to 602

energy ratio of their requirement is higher than for younger age groups. Thus, unless the elderly people are 603

physically active they may need a more protein-dense diet. 604

In France, an intake of 1.0 g/kg body weight per day has been recommended for people ≥75 years based on 605

considerations about protein metabolism regulation in the elderly (AFSSA, 2007). The German speaking 606

countries (D-A-CH, 2008) recommended an intake of 0.8 g protein/kg body weight per day for adults, and 607

the same recommendation was made for adults aged 65 years and older since it was considered that the 608

available evidence was insufficient to prove a higher requirement for the elderly. 609

4.2. Dietary reference values for protein for infants and children 610

Table 3 lists reference intakes set by various organisations for infants and children. 611

In their report, FAO/WHO/UNU (1985) calculated protein requirements of children from six months 612

onwards by a modified factorial method. Maintenance requirements were interpolated between the values 613

from nitrogen balance studies for children aged one year and for young adults aged 20 years. A coefficient of 614

variation of 12.5 % was used to allow for individual variability. The growth component of the protein 615

requirement was set at 50 % above that based on the theoretical daily amount of nitrogen laid down, 616

corrected for an efficiency of protein utilisation of 70 %. The average requirement was then estimated as the 617

sum of maintenance and growth requirement. The “safe level of intake” was estimated based on the average 618

requirement plus two standard deviations corresponding to a CV of 12-16 %. 619

In its re-evaluation, WHO/FAO/UNU (2007) calculated a maintenance value of 0.66 g protein/kg body 620

weight per day for children and infants from 6 months to 18 years. The maintenance level was derived from 621

a regression analysis of nitrogen balance studies on children from 6 months to 12 years. Protein deposition 622

needs were calculated from combined data of two studies, and assuming an efficiency of utilisation for 623

growth of 58 %. The average requirement was then estimated as the sum of maintenance and growth 624

requirement. The “safe level of intake” was estimated based on the average level plus 1.96 SD. Requirements 625

fall very rapidly in the first two years of life (safe level at six months of age: 1.31 g/kg body weight per day; 626

at two years of age: 0.97 g/kg body weight per day). Thereafter, the decrease towards the adult level is very 627

slow (WHO/FAO/UNU, 2007). 628

Dewey et al. (1996) reviewed the approach by FAO/WHO/UNU (1985) and suggested revised estimates for 629

protein requirements for infants and children. The German speaking countries (D-A-CH, 2008) followed the 630

proposal of Dewey et al. (1996). For infants aged from 6 to <12 months the maintenance requirement was 631

estimated from nitrogen balance studies at 0.56 g/kg body weight per day. Age dependent additions of 632

between 35 % and 31 % for the increase in body protein were made to take into account inter-individual 633

variability of maintenance and growth requirements (Dewey et al., 1996). A recommended intake of 1.1 g/kg 634

body weight per day (10 g/d) of high quality protein was established between 6 and <12 months. 635

Recommended intakes were established for children aged 1 to <4 years (1.0 g/kg body weight per day) and

636

4 to <15 years (0.9 g/kg body weight per day), and for boys aged 15 to <19 years (0.9 g/kg body weight per 637

day) and girls aged 15 to <19 years (0.8 g/kg body weight per day). Maintenance requirement was estimated 638

at 0.63 g/kg body weight per day (Dewey et al., 1996) and total requirement, allowing for the decreasing 639

growth requirement with age, was estimated to range from 0.63 to 0.7 g/kg body weight per day. An 640

additional 30 % allowance was made to account for inter-individual variability in protein utilisation and 641

digestibility. 642

The Nordic Nutrition recommendations (NNR, 2004) also followed the approach by Dewey et al. (1996) to 643

establish recommended intakes of 1.1 and 1.0 g/kg body weight per day for infants aged 6-11 months and 644

children aged 12-23 months, respectively. For children aged 2-17 years a recommended intake of 0.9 g/kg 645

body weight per day was established, in agreement with the values in other recommendations (D-A-CH, 646

2008; Health Council of the Netherlands, 2001; IoM, 2005). The French recommendations (AFSSA, 2007) 647

also followed the approach of Dewey et al. (1996). 648

Dietary reference values for protein

EFSA Journal 20xx;xxxx 17

The Health Council of the Netherlands (2001) used a factorial method derived from nitrogen balance 649

experiments to estimate the protein requirements of infants over six months, children and adolescents. For 650

infants aged 6-11 months a recommended intake of 1.2 g/kg body weight per day (10 g/d) of high quality 651

protein was established. This was based on an average requirement for maintenance and growth of 0.9 g/kg 652

body weight per day, with a CV of 15 % to allow for individual variability, and assuming an efficiency of 653

protein utilisation of 70 %. Recommended intakes were established for children aged 1 to 13 years (0.9 g/kg 654

body weight per day) and 14 to 18 years (0.8 g/kg body weight per day), on the same basis but using an 655

average requirement for maintenance and growth of 0.8 g/kg body weight per day for children aged 1 to 656

3 years, and 0.7 g/kg body weight per day for children aged 4 to 18 years (Health Council of the Netherlands, 657

2001). 658

Table 3: Overview of dietary reference values for protein for children. 659

FAO/

WHO/

UNU

(1985)

SCF

(1993)

Health Council

of the

Netherlands

(2001)

NNR

(2004)

IoM (2005)

WHO/

FAO/

UNU

(2007)

AFSSA (2007) D-A-CH

(2008)

Age

6–9

months

7-9

months

6-11 months 6-11

months

7-12 months 6 months 6-12 months 6-<12

months

PRI

(g/kg bw x d

-1

)

1.65

(m + f)

1.65

(m + f)

1.2

(m + f)

1.1

(m + f)

1.2

(m + f)

1.31

(m + f)

1.1

(m + f)

1.1

(m + f)

Age

9-12

months

10-12

months

1-13 y 1-1.9 y 1-3 y 1 y 12-24 months 1- <4 y

PRI

(g/kg bw x d

-1

)

1.50

(m + f)

1.48

(m + f)

0.9

(m + f)

1.0

(m + f)

1.05

(m + f)

1.14

(m + f)

1.0 (m+f) 1.0

(m + f)

Age

1-2 y 1-1.5 y 1.5 y 24-36 months

PRI

(g/kg bw x d

-1

)

1.20

(m + f)

1.26

(m + f)

1.03

(m + f)

0.9 (m+f)

Age

2-3 y 2-3 y 2-17 y 2 y 3-10 y

PRI

(g/kg bw x d

-1

)

1.15

(m + f)

1.13

(m + f)

0.9

(m + f)

0.97

(m + f)

0.9 (m+f)

Age

3-5 y 4-5 y 3 y 10-12 y (m),

10-11 y (f)

PRI

(g/kg bw x d

-1

)

1.10

(m + f)

1.06

(m + f)

0.90

(m + f)

0.85 (m),

0.9 (f)

Age

5-12 y 6-9 y 4-13 y 4-6 y 12-13 y (m),

11-14 y (f)

4-<15 y

PRI

(g/kg bw x d

-1

)

1.0

(m + f)

1.01

(m + f)

0.95

(m + f)

0.87

(m + f)

0.9 (m),

0.85 (f)

0.9

(m + f)

Age

12-14 y 12 y 7-10 y 13-17 y (m), 14-

16 y (f)

PRI

(g/kg bw x d

-1

)

1.0 (m)

0.95 (f)

1.0 (m)

0.96 (f)

0.92

(m + f)

0.85 (m),

0.8 (f)

Age

14-16 y

14 y 14-18 y 14-18 y 11-14 y

PRI

(g/kg bw x d

-1

)

0.95 (m)

0.9 (f)

0.96 (m)

0.90 (f)

0.8

(m + f)

0.85

(m + f)

0.90 (m)

0.89 (f)

Age

16-18 y 16 y 15-18 y 17-18 y (m), 16-

18 y (f)

15-<19 y

PRI

(g/kg bw x d

-1

)

0.9 (m)

0.8 (f)

0.90 (m)

0.83 (f)

0.87 (m)

0.84 (f)

0.8 (m+f) 0.9 (m)

0.8 (f)

Safe level of intake;

RDA 660

661

The US Institute of Medicine recommended intakes ranging from 1.2 g/kg body weight per day of high 662

quality protein for infants aged 6-12 months to 0.85 g/kg body weight per day for 14 to 18 year-old boys and 663

girls based on estimates of requirements for maintenance, with additions for growth (IoM, 2005). 664

Maintenance requirements were estimated from short-term nitrogen balance studies in older infants and 665

children as 110 mg N/kg body weight per day for ages 7 months through 13 years, and as 105 mg N/kg body 666

weight per day (estimated from short-term nitrogen balance studies in adults and based on a meta-analysis by 667

Dietary reference values for protein

EFSA Journal 20xx;xxxx 18

Rand et al. (2003)) for ages 14 through 18 years. Growth requirements were estimated in infants and children 668

from estimated rates of nitrogen accretion calculated from rates of weight gain and from estimates of the 669

nitrogen content of tissues. The efficiency of dietary protein utilisation was assumed to be 58 % for ages 670

7 months through 13 years and 47 % for ages 14 through 18 years, estimated from the slopes of the nitrogen 671

balance data. The EAR was thus estimated as 1.0 g/kg body weight per day for infants aged 7-12 months, 672

0.87 and 0.76 for boys and girls aged 1-3 and 4-13 years, respectively, and 0.73 and 0.71 for boys and girls 673

aged 14-18 years, respectively. A CV of 12 % for maintenance and 43 % for growth was used to allow for 674

individual variability in the calculation of the RDA (IoM, 2005). 675

4.3. Dietary reference values for protein during pregnancy 676

FAO/WHO/UNU (1985) recommended an average additional intake of 6 g/d throughout pregnancy, based 677

on derived additional levels of protein intake of 1.2 g/d, 6.1 g/d and 10.7 g/d for the first, second and third 678

trimester, respectively. This was based on the calculated average increment of 925 g protein during a 679

pregnancy, plus 30 % (2 SD of birth weight), adjusted for the efficiency with which dietary protein is 680

converted to foetal, placental and maternal tissues (estimated as 70 %) (FAO/WHO/UNU, 1985). 681

WHO/FAO/UNU (2007) revised this value and recommended 1, 9 and 31 g of additional protein/d in the 682

first, second and third trimester, respectively, as “safe intake levels”. Based on a theoretical model (Hytten 683

and Chamberlain, 1991), the total deposition of protein in the foetus and maternal tissue has been estimated 684

to be 925 g (assuming a 12.5 kg gestational weight gain), of which 42 % is deposited in the foetus, 17 % in 685

the uterus, 14 % in the blood, 10 % in the placenta and 8 % in the breasts. Protein deposition has also been 686

estimated indirectly from measurements of total body potassium accretion, measured by whole body 687

counting in a number of studies with pregnant women (Butte et al., 2003; Forsum et al., 1988; King et al., 688

1973; Pipe et al., 1979). From these studies, mean protein deposition during pregnancy was estimated as 689

686 g (WHO/FAO/UNU, 2007). Based on the study by Butte et al. (2003), protein deposition per trimester 690

was then calculated for well-nourished women achieving a gestational weight gain of 13.8 kg (the mid-point 691

of the recommended weight gain range for women with normal pre-pregnancy weight) (IoM, 1990). The 692

efficiency of protein utilisation was taken to be 42 % in pregnant women (in comparison to 47 % in non-693

pregnant adults) (WHO/FAO/UNU, 2007). 694

In Europe, the UK COMA (DoH, 1991) accepted the value proposed by FAO/WHO/UNU (1985). The SCF 695

(1993) used the approach of FAO/WHO/UNU (1985) but recommended an additional intake of 10 g/d 696

throughout pregnancy because of uncertainty about changes in protein metabolism associated with 697

pregnancy (SCF, 1993). The Dutch (Health Council of the Netherlands, 2001) recommended an additional 698

intake of 0.1 g/kg body weight per day throughout pregnancy. AFSSA (2007) followed the approach of 699

FAO/WHO/UNU (1985) and recommended an intake between about 0.82 and 1 g/kg body weight per day 700

for a woman of 60 kg (calculated from 50, 55 and 60 g/d for each trimester of pregnancy). The German 701

speaking countries (D-A-CH, 2008) recommended an additional intake of 10 g/d (for the second and third 702

trimesters). 703

The US Institute of Medicine set the EAR at 21 g/d above the average protein requirements of non-pregnant

704

women, averaging the overall protein needs over the last two trimesters of pregnancy (IoM, 2005). It 705

recommended an additional intake of 25 g/d (RDA for the second and third trimesters), assuming a CV of 706

12 % (26 g protein) and rounding to the nearest 5 g/d. The EAR for additional protein needs was based upon 707

an estimated average protein deposition of 12.6 g/d over the second and third trimesters (calculated from 708

potassium retention studies for accretion of 5.4 g protein/d), assuming an efficiency of dietary protein 709

utilisation of 43 %, plus an additional 8.4 g/d for maintenance of the increased body tissue. 710

4.4. Dietary reference values for protein during lactation 711

FAO/WHO/UNU (1985) recommended an additional intake of 16 g/d of high quality protein during the first 712

six months of lactation, 12 g/d during the second six months, and 11 g/d thereafter. This is based on the 713

average protein content of breast milk, an efficiency factor of 70 % to adjust for the conversion of dietary 714

protein to milk protein, and a CV of breast-milk volume of 12.5 % (FAO/WHO/UNU, 1985). 715

WHO/FAO/UNU (2007) revised this value and recommended an average value of additional protein intake 716

of 19 g/d in the first six months of lactation and 12.5 g/d after six months. This is based on the increased 717

Dietary reference values for protein

EFSA Journal 20xx;xxxx 19

nitrogen needs of lactating women to synthesise milk proteins, with the assumption that the efficiency of 718

milk protein production is the same as the efficiency of protein synthesis in non-lactating adults, i.e. 47 %. 719

Therefore, the additional “safe intake” of dietary protein was calculated using an amount of dietary protein 720

equal to milk protein, taking into account an efficiency of 47 %, and adding 1.96 SD corresponding to a CV 721

of 12 % (WHO/FAO/UNU, 2007). 722

In Europe, the UK COMA (DoH, 1991) recommended an additional intake of 11 g/d for the first six months 723

and an additional intake of 8 g/d thereafter. The approach used was similar to that of FAO/WHO/UNU 724

(1985), except that the values used for breast milk protein content were lower because of correction for the 725

amount (up to 25 %) of non-protein nitrogen present. The SCF (1993) accepted the values proposed by 726

FAO/WHO/UNU (1985), i.e. an additional intake of 16 g/d of high quality protein during the first six months 727

of lactation and 12 g/d during the second six months. The Netherlands (Health Council of the Netherlands, 728

2001) recommended an additional intake of 0.2 g/kg body weight per day during lactation to allow for the 729

additional protein loss of about 7 g/d in breast milk. AFSSA considered the quantity of protein and non-730

protein nitrogen excreted in milk and its change during lactation, and recommended an additional intake of 731

16 g/d for the first six months, resulting in a recommended intake of about 1.1 g/kg body weight per day for 732

a woman of 60 kg (AFSSA, 2007). The German speaking countries (D-A-CH, 2008) recommended an 733

additional intake of 15 g/d during lactation based on a mean protein loss of 7-9 g/d in breast milk, assuming 734

an efficiency of utilisation of 70 % and adding 2 SD to account for inter-individual variability. 735

The US Institute of Medicine (IoM, 2005) calculated the EAR of additional protein during lactation (21 g/d) 736

from the average protein equivalent of milk nitrogen output and an assumed efficiency of utilisation of 47 %. 737

Adding 2 SD (24 %) to account for inter-individual variability yielded an RDA of +25 g/d, or a 738

recommended protein intake of 1.3 g/kg body weight per day during lactation. 739

4.5. Requirements for indispensable amino acids 740

Different approaches have been used to determine indispensable amino acid requirements. These 741

requirements were first determined in adults using a nitrogen balance approach (Rose, 1957). The values 742

obtained by this approach are usually considered to underestimate the requirements (Rand and Young, 1999; 743

WHO/FAO/UNU, 2007; Young and Marchini, 1990). More recent data in adults have been obtained using 744

amino acids labelled with stable isotopes, and are based on the measurement of amino acid oxidation as a 745

function of intake (Bos et al., 2002). This includes the indicator amino acid balance method (Young and 746

Borgonha, 2000), the indicator amino acid oxidation method (Elango et al., 2008a, 2008b; Pencharz and 747

Ball, 2003), the 24 h-indicator amino acid oxidation method (Kurpad et al., 2001) or the protein post-748

prandial retention method (Bos et al., 2005; Millward et al., 2000). 749

The rationale for deriving DRVs for each indispensable amino acid remains questionable since as a rule 750

amino acids are not provided as individual nutrients in the diet, but in the form of protein. Moreover, the 751

values obtained for indispensable amino acid requirements are not yet sufficiently precise, and require 752

further investigation (AFSSA, 2007; WHO/FAO/UNU, 2007). Only the US has introduced specific RDAs 753

for indispensable amino acids, derived from the average values of requirements deduced from amino acid 754

oxidation methods and adding 2 CV (of 12 %) (IoM, 2005). 755

Average indispensable amino acid requirements are used to calculate the indispensable amino acid reference 756

pattern, which is used in the assessment of protein quality according to the chemical score approach and the 757

PD-CAAS. The mean values for indispensable amino acid requirements were provided in the 758

WHO/FAO/UNU (2007) report. 759

Dietary reference values for protein

EFSA Journal 20xx;xxxx 20

Table 4: Mean requirements for indispensable amino acids in adults (WHO/FAO/UNU, 2007). 760

mg/kg x d

-1

mg/kg x d

-1

Histidine

Phenylalanine+tyrosine

Isoleucine

Threonine

Leucine

Tryptophan

Lysine

Valine

Methionine+cysteine

methionine

cysteine

10.4

4.1

Total

184

resulting from rounding 761

762

The amino acid requirements of infants and children have been derived using a factorial method, based on 763

the estimated protein requirements for maintenance and growth (Dewey et al., 1996; WHO/FAO/UNU, 764

2007) (Table 5). It is assumed that the required amino acid pattern for maintenance is the same as that for 765

adults, and that the amino acid pattern required for growth is given by the amino acid composition of whole-766

body tissue protein (Davis et al., 1993; Dewey et al., 1996; Widdowson et al., 1979). 767

Table 5: Mean requirements for indispensable amino acids in infants, children and adolescents 768

(WHO/FAO/UNU, 2007). 769

Mean amino acid requirement at different ages (mg/kg x d

-1

)

0.5 years 1-2 years 3-10 years 11-14 years 15-18 years

Histidine

22 15 12 12 11

Isoleucine

36 27 23 22 21

Leucine

73 54 44 44 42

Lysine

64 45 35 35 33

Methionine+cysteine

31 22 18 17 16

Phen

lalanine+t

rosine

59 40 30 30 28

Threonine

34 23 18 18 17

Tryptophan

9.5 6.4 4.8 4.8 4.5

Valine

49 36 29 29 28

770

5. Criteria (endpoints) on which to base dietary reference values (DRVs) 771

Current DRVs for protein are based on protein homeostasis measured as nitrogen balance. DRVs also take 772

into account protein quality, which is related to the capacity of a protein source to meet both the requirement 773

for nitrogen and the requirement for indispensable amino acids as limiting precursors for body protein 774

synthesis. Other criteria taking into account functional and health consequences of protein intake may also be 775

considered in order to derive reference values for protein intake. 776

5.1. Protein intake and protein and nitrogen homeostasis 777

5.1.1. Methods for the determination of protein requirement 778

5.1.1.1. Nitrogen balance 779

Nitrogen balance is the classical approach for the determination of protein requirement, and in the initial 780

studies of indispensable amino acid requirements (FAO/WHO/UNU, 1985). Nitrogen balance is the 781

difference between nitrogen intake and the amount lost in urine, faeces, and via the skin and other routes 782

such as nasal secretions, menstrual losses or seminal fluid (IoM, 2005). In healthy adults at energy balance 783

the protein requirement (maintenance requirement) is defined as that amount of dietary protein sufficient to 784

achieve zero nitrogen balance. It is assumed that nitrogen balance will be negative when protein intakes are 785

inadequate. In infants and children, nitrogen balance has to be positive to allow for growth. While the 786

method has substantial practical limitations, mainly related to the accuracy of the measurements and the 787

Dietary reference values for protein

EFSA Journal 20xx;xxxx 21

interpretation of the results (WHO/FAO/UNU, 2007), it remains the method of choice for determining 788

protein requirement in adults (Rand et al., 2003). 789

5.1.1.2. The factorial method 790

The factorial approach is based on the assessment of the extent to which dietary protein nitrogen is absorbed 791

and retained by the organism, and is able to balance daily nitrogen losses and to allow additional protein 792

deposition in newly formed tissue for growth and in specific physiological conditions such as pregnancy or 793

lactation. Obligatory nitrogen losses are estimated from subjects fed a diet that meets energy needs but is 794

essentially protein-free, or more reliably are derived from the y-intercept of the slope of the regression line 795

relating nitrogen intake to nitrogen retention. The requirement for dietary protein is considered to be the 796

amount needed to replace nitrogen losses and to allow additional protein deposition, after adjustment for the 797

efficiency of dietary protein utilisation (see section 2.4) and the quality of the dietary protein. The factorial 798

method is used to calculate protein requirements in physiological conditions such as growth, pregnancy or 799

lactation. A critical factor is the value used for efficiency of dietary protein utilisation. 800

Table 6: Previously used values for protein efficiency in different population groups and values used by 801

EFSA. 802

Population group Previously used values (%) Values used by EFSA (%)

Adults

(1)

, 47

(2)

Infants and children (for maintenance

and growth, respectively)

(1)

, 47/58

(2,3)

47/58

Pregnancy (for protein deposition)

(1)

, 42

(2)

, 43

(3)

Lactation

(1)

, 47

(2)

FAO/WHO/UNU (1985);

WHO/FAO/UNU (2007);

IoM (2005) 803

804

In healthy adults, the mean post-prandial protein efficiency in controlled optimal conditions is considered to 805

be 70 %, and this value was first used in FAO/WHO/UNU (1985) as a reference for the different population 806

groups including infants and women during pregnancy and lactation. However, the NPU value can be 807

modified by various factors including the food matrix, the diet and certain physiological conditions. More 808

recently, a value of 47 % was derived from nitrogen balance studies in healthy adults under maintenance 809

conditions (Rand et al., 2003). For children, WHO/FAO/UNU (2007) estimated the NPU for protein 810

deposition with growth to be 58 % from 6 months to 18 years, whereas IoM (2005) estimated it to be 58 % 811

from 7 months to 13 years, and 47 % from 14 to 18 years. During lactation the NPU was estimated to be 812

47 %, and not to be different from that in non-lactating healthy adults (WHO/FAO/UNU, 2007). For ten 813

pregnant adolescents, King et al. (1973) derived a relatively low value of nitrogen retention of 30 %. From 814

different nitrogen balance studies, Calloway (1974) calculated a nitrogen retention of 25-30 %. However, in 815

healthy pregnant women nitrogen efficiency was found to be increased in comparison with non-pregnant 816

women receiving the same nitrogen intake above the requirement (Mojtahedi et al., 2002). From the study by 817

King et al. (1973), IoM (2005) recalculated an NPU value of 43 % based on those six adolescents who 818

demonstrated a positive efficiency at multiple levels of protein intake, and WHO/FAO/UNU (2007) 819

recalculated the efficiency of utilisation of dietary protein to be 42 % after omitting the two subjects who 820

gave negative gradients. Eight pregnant Indian women utilised 47 % of the dietary nitrogen when 60-118 g/d 821

of mixed protein was consumed. The nitrogen intake of the Indian women was unrelated to nitrogen 822

retention unless intakes above 0.45 g N/kg body weight per day were omitted (Jayalakshmi et al., 1959). A 823

similar range of values has been observed in pregnant sows (Dunn and Speer, 1991; Jones and Maxwell, 824

1982; King and Brown, 1993; Renteria-Flores et al., 2008; Theil et al., 2002). 825

The Panel considers that for healthy adults a protein efficiency value of 47 % is reasonable since it is the 826

value derived from the nitrogen balance studies used to define nitrogen requirement in adults. There is no 827

convincing scientific evidence that protein efficiency for maintenance of body protein and for protein 828

deposition is lower during pregnancy or lactation. As a consequence, the same value can be considered as 829

that determined for healthy adults (47 %). For infants and children, a value of 58 % for growth is justified 830

Dietary reference values for protein

EFSA Journal 20xx;xxxx 22

because of an increased efficiency of dietary protein utilisation, whilst for maintenance the same protein 831

efficiency as for adults is applied. 832

5.1.1.3. Protein quality and reference pattern for indispensable amino acids 833

The protein requirement is dependent on the dietary protein quality, which is mainly determined by the 834

pattern of indispensable amino acids in the protein. The reference pattern of amino acids for infants 835

<0.5 years is the amino acid pattern of human milk. The reference pattern of amino acids (mg/g protein) for 836

the assessment of protein quality for adults is derived from proposed data on the requirement for individual 837

indispensable amino acids (WHO/FAO/UNU, 2007) by dividing the requirement (mg amino acid/kg body 838

weight per day) by the average requirement for protein (g/kg body weight per day). Age specific scoring 839

patterns for dietary proteins can be derived by dividing the requirement of each indispensable amino acid by 840

the protein requirement of the selected age group (WHO/FAO/UNU, 2007) (Table 7). 841

In practice, three reference patterns are used: the amino acid pattern of human milk for infants <0.5 years, the 842

3-10 years reference pattern for infants and children, and the adult reference pattern. 843

Table 7: Scoring pattern (indispensable amino acid reference profiles) for infants, children, adolescents 844

and adults (WHO/FAO/UNU, 2007). 845

Infants, children, adolescents (mg/g protein)

Adults

(mg/g protein)

0.5 years 1-2 years 3-10 years 11-14 years 15-18 years

Histidine

20 18 16 16 16 15

Isoleucine

32 31 31 30 30 30

Leucine

66 63 61 60 60 59

Lysine

57 52 48 48 47 45

Methionine+cysteine

28 26 24 23 23 22

Phenylalanine+tyrosine

52 46 41 41 40 30

Threonine

31 27 25 25 24 23

Tryptophan

8.5 7.4 6.6 6.5 6.3 6

Valine

43 42 40 40 40 39

5.1.2. Protein requirement of adults 846

In a meta-analysis by Rand et al. (2003), available nitrogen balance data as a function of nitrogen intake 847

among healthy persons were analysed. Data obtained from 235 individuals, each studied at ≥3 test protein 848

intakes, were gathered from 19 primary and secondary studies, and used for estimating the average 849

requirement. Subjects were classified by sex and age (≤55 (n=221) and >55 years of age (n=14)), diets were 850

classified by the main source of protein (animal (>90 % of total protein intake from animal sources), 851

vegetable (>90 % of total protein intake from vegetable sources) or mixed), and climate was classified as 852

temperate or tropical. As the distribution of individual requirements was significantly skewed and kurtotic, 853

the mean was not a robust estimate of the centre of the population, and the median was taken as the average 854

requirement. 855

The Panel notes that the study by Rand et al. (2003) concluded that the best estimate of average requirement 856

for 235 healthy adults from 19 studies was 105 mg N/kg body weight per day (0.66 g high quality protein/kg 857

per day). The 97.5

percentile of the population distribution of the requirement was estimated from the log 858

median plus 1.96 times the SD of 0.12, and found to be 133 mg N/kg body weight per day (0.83 g high 859

quality protein/kg body weight per day). Thus, 0.83 g protein/kg body weight per day can be expected to 860

meet the requirements of most (97.5 %) of the healthy adult population. This value can be considered to 861

fulfil the function of a PRI even though derived differently. The data did not provide sufficient statistical 862

power to establish different requirements for different adult groups based on age, sex or dietary protein 863

source (animal or vegetable proteins) (Rand et al., 2003). The Panel notes that considering only the primary 864

studies based on 32 data points the requirement would be 101.5 mg/kg body weight per day, but that the 865

statistical power is greatly reduced and that this value is not significantly different to the value of 105 mg 866

N/kg body weight per day. 867

Dietary reference values for protein

EFSA Journal 20xx;xxxx 23

The Panel considers that the value of 0.66 g/kg body weight per day can be accepted as the AR and the value 868

of 0.83 g/kg body weight per day as the PRI derived for proteins with a PD-CAAS value of 1.0. This value 869

can be applied to usual mixed diets in Europe which are unlikely to be limiting in their content of 870

indispensable amino acids (WHO/FAO/UNU, 2007). 871

5.1.2.1. Older adults 872

Few data are available on the protein requirement of older adults compared to young and middle aged adults. 873

A negative nitrogen balance was observed in six elderly females (69 ± 5 years) consuming a diet providing 874

0.8 g protein/kg body weight per day for two weeks (Pannemans et al., 1997), and the same level of intake 875

was associated with a decrease in the mid-thigh muscle area in ten men and women (aged 55-77 years) 876

during 14 weeks, although whole body leucine metabolism and whole body composition were not affected 877

(Campbell et al., 2001). Several studies concluded that the PRI for older adults may be greater than that for 878

younger adults (0.83 g/kg body weight per day) (Gaffney-Stomberg et al., 2009; Thalacker-Mercer et al., 879

2010; Wolfe et al., 2008). This was particularly deduced from an assumed, although not significantly, lower 880

efficiency of protein utilisation in the elderly (AFSSA, 2007; Rand et al., 2003). However, one study did not 881

show differences between younger (21-46 years) and older (63-81 years) subjects after short-term assessment 882

of nitrogen balance (Campbell et al., 2008). Some authors (Campbell and Leidy, 2007; Iglay et al., 2009) 883

found that an increase in dietary protein alone does not change body composition or improve lean body mass 884

unless accompanied by physical training programmes. 885

The Panel concludes that the available data are insufficient to specifically determine the protein requirement 886

in the elderly, and that at least the same level of protein intake as for young adults has to be proposed for 887

older adults. 888

5.1.3. Protein requirement of infants and children 889

The protein requirement of infants and children includes two components, i.e. maintenance requirement and 890

growth requirement. This protein requirement can be defined as the minimum intake that will permit a 891

positive nitrogen equilibrium to allow for growth in normally growing subjects who have an appropriate 892

body composition, are in energy balance and are moderately physically active (WHO/FAO/UNU, 2007). 893

In the report by WHO/FAO/UNU (2007), estimates of the protein requirement from 6 months to 18 years 894

were derived factorially as the sum of requirements for maintenance and growth corrected for efficiency of 895

dietary protein utilisation. An average maintenance requirement of 0.66 g/kg body weight per day protein 896

was applied to infants and children from 6 months to 18 years (Tables 8 and 9). Regression analysis of 897

nitrogen balance studies on children from 6 months to 12 years resulted in a maintenance level of 110 mg 898

N/kg body weight per day. Because this value was close to the adult maintenance value of 105 mg N/kg 899

body weight per day and it could not be determined with certainty that maintenance values for infants and 900

children differ from those for adults, the latter value was selected for the maintenance value for ages from six 901

months onwards. Average daily needs for dietary protein for growth were estimated from average daily rates 902

of protein deposition, calculated from studies on whole-body potassium deposition, and adjusted by an 903

efficiency of utilisation of dietary protein of 58 %. The total average requirement for protein was adjusted 904

according to the expected variability of maintenance and growth to give a value equivalent to the 97.5

905

percentile of the distribution as a measure of the PRI, based on the average requirement plus 1.96 SD. 906

The Panel agrees with the analysis of the data. 907

Dietary reference values for protein

EFSA Journal 20xx;xxxx 24

Table 8: Average protein requirement of infants from 6 months onwards and children up to 10 years of 908

age derived by WHO/FAO/UNU (2007). 909

Age (years) 0.5 1 1.5 2 3 4 5 6 7 8 9 10

Maintenance

requirement

(g/kg bw x d

-1

)

0.66 0.66 0.66 0.66 0.66 0.66 0.66 0.66 0.66 0.66 0.66 0.66

Growth

requirement

(g/kg bw x d

-1

)

0.46 0.29 0.19 0.13 0.07 0.03 0.03 0.06 0.08 0.09 0.09 0.09

Average

requirement

(g/kg bw x d

-1

)

1.12 0.95 0.85 0.79 0.73 0.69 0.69 0.72 0.74 0.75 0.75 0.75

910

Table 9: Average protein requirement of adolescents derived by WHO/FAO/UNU (2007). 911

Age (years) 11 12 13 14 15 16 17 18

Maintenance

requirement

(g/kg bw x d

-1

)

0.66 0.66 0.66 0.66 0.66 0.66 0.66 0.66

Growth requirement

(g/kg bw x d

-1

)

0.09 (m)

0.07 (f)

0.08 (m)

0.06 (f)

0.07 (m)

0.05 (f)

0.06 (m)

0.04 (f)

0.06 (m)

0.03 (f)

0.05 (m)

0.02 (f)

0.04 (m)

0.01 (f)

0.03 (m)

0.00 (f)

Average requirement

(g/kg bw x d

-1

)

0.75 (m)

0.73 (f)

0.74 (m)

0.72 (f)

0.73 (m)

0.71 (f)

0.72 (m)

0.70 (f)

0.72 (m)

0.69 (f)

0.71 (m)

0.68 (f)

0.70 (m)

0.67 (f)

0.69 (m)

0.66 (f)

5.1.4. Protein requirement during pregnancy 912

The protein requirement during pregnancy has to take into account the requirements for the deposition of 913

new protein and the requirement for the maintenance of the weight gained, in addition to the requirement in 914

the non-pregnant state. It can be determined by using either the nitrogen balance approach or the factorial 915

approach. 916

In the nitrogen balance approach, nitrogen requirement is derived from nitrogen balance studies. This 917

requires balance measurements in women at different levels of protein intake in order to determine the 918

maximal nitrogen deposition potential, and to derive the nitrogen requirement from this maximal nitrogen 919

deposition (Calloway, 1974). However, it appears from the available studies that there is a linear increase in 920

apparent nitrogen deposition with increasing protein intake in pregnant women. The linear relationship 921

between nitrogen intake and deposition towards the end of pregnancy is statistically significant

(Calloway, 922

1974; Jayalakshmi et al., 1959; Johnstone et al., 1981; King et al., 1973). 923

According to the slope of these equations, the average nitrogen efficiency is very low, i.e. between 21 and 924

47 %. The linear nature of the relation between nitrogen intake and retention does not permit the 925

determination of a maximal nitrogen deposition potential, nor to derive a nitrogen requirement related to this 926

maximal nitrogen deposition. The cause for this linear relationship remains unclear. This linear relation and 927

the low level of nitrogen efficiency derived from the slopes indicate uncertainties and errors in the 928

measurement of nitrogen balance, and implicate important limitations for the use of this approach to 929

determine the nitrogen requirement in pregnant women. 930

The alternative approach is the factorial approach used by IoM (2005) and WHO/FAO/UNU (2007). The 931

maintenance costs were based upon the mid-trimester increase in maternal body weight, and the maintenance 932

value of 0.66 g/kg body weight per day was derived from the average requirement in healthy adults, 933

assuming a CV of 12 %. Protein deposition in the foetus and maternal tissue has been estimated indirectly 934

In the study by Jayalakshmi et al. (1959), a linear relationship was only obtained after exclusion of four values indicating nitrogen

retention for intakes >0.45 g N/kg body weight per day.

Dietary reference values for protein

EFSA Journal 20xx;xxxx 25

from measurements of total body potassium accretion. However, studies show that protein is not deposited 935

equally throughout pregnancy. For well-nourished women with a gestational weight gain of 13.8 kg, total 936

protein deposition was estimated as 1.9 g/d in the second trimester and 7.4 g/d in the third trimester (Butte et 937

al., 2003; WHO/FAO/UNU, 2007). For protein deposition towards the end of pregnancy, IoM (2005) derived 938

a mean value of 7.2 g/d based on six studies estimating the increase in whole body potassium during 939

pregnancy in 120 women. They then assumed that nitrogen accretion during the second trimester is only 940

about half of that observed in the third trimester, leading to an estimated value for protein deposition of 941

3.6 g/d for the second trimester. 942

Based on an efficiency of protein utilisation of 42 %, WHO/FAO/UNU (2007) estimated that an additional 943

1, 9 and 31 g protein/d in the first, second and third trimesters, respectively, are required to support a 944

gestational weight gain of 13.8 kg. 945

The Panel notes that a 42 % efficiency of protein utilisation is low, and cannot see a plausible reason to 946

depart from the value of 47 % derived for adults for maintenance of body protein (see also section 5.1.1.2). 947

5.1.5. Protein requirement during lactation 948

The additional protein requirement for milk production can be estimated factorially from milk protein output 949

and the efficiency of dietary protein utilisation for milk protein production. The efficiency of protein 950

utilisation for milk protein production is unknown and was taken to be the same as for protein deposition in 951

the non-lactating adult (47 %). In the report by WHO/FAO/UNU (2007), mean rates of milk production by 952

well-nourished women exclusively breastfeeding their infants during the first six months postpartum and 953

partially breastfeeding in the second six months postpartum, together with the mean concentrations of protein 954

and non-protein nitrogen in human milk, were used to calculate mean milk protein output. The factor of 6.25 955

was used to convert milk nitrogen to protein. Thus, the additional dietary protein requirement during 956

lactation will be an amount of dietary protein equal to milk protein output, taking into account an efficiency 957

of protein utilisation of 47 %. Assuming a CV of 12 %, the additional protein intakes during the first six 958

months of lactation were estimated as 19 g protein/d, falling to 13 g protein/d after six months. 959

The Panel accepts the approach of WHO/FAO/UNU (2007). 960

5.2. Protein intake and health consequences 961

Protein requirement and PRI are derived from nitrogen balance but several health outcomes associated with 962

protein intake could also be considered as criteria for setting DRVs for protein. It is conceivable that, in case 963

of sufficient evidence for a positive effect on health, a PRI for protein above the PRI derived from nitrogen 964

balances and factorial estimates would result. In addition, potentially adverse effects on health should be 965

taken into account when assessing a protein intake above the PRI derived from nitrogen balance. 966

5.2.1. Muscle mass 967

The major anabolic influences on muscle are contractile activity and feeding. Ingestion of sufficient dietary

968

energy and protein is a prerequisite for muscle protein synthesis and maintenance of muscle mass and 969

function. 970

As a result of feeding, anabolism occurs chiefly by an increase in protein synthesis. Insulin has a permissive 971

role in increasing synthesis, and the availability of amino acids is crucial for net anabolism. In vivo, amino 972

acids display an anabolic effect (Giordano et al., 1996; Volpi et al., 1996) and were shown to stimulate 973

muscle protein synthesis (Bohe et al., 2003; Liu et al., 2002; Nair and Short, 2005; Nygren and Nair, 2003). 974

There was no effect of a dietary protein level above the PRI on muscle mass and protein content, and a high 975

protein diet of around 2 g/kg body weight per day has not been demonstrated to modulate skeletal protein 976

synthesis in both exercising and non-exercising human subjects (Bolster et al., 2005; IoM, 2005; Juillet et al., 977

2008) or in animals (Almurshed and Grunewald, 2000; Chevalier et al., 2009; Masanés et al., 1999; Morens 978

et al., 2001; Taillandier et al., 2003). However, increasing protein intake above the individual requirement 979

increases amino acid oxidation and modifies protein turnover. When protein intake is increased from around 980

1 g/kg body weight per day to 2 g/kg body weight per day, the increase of amino acid oxidation is associated 981

Dietary reference values for protein

EFSA Journal 20xx;xxxx 26

with stimulation of protein breakdown rates in the fasted state and a strong inhibition in the fed state, 982

whereas whole-body protein synthesis rates are little affected (Forslund et al., 1998; Fouillet et al., 2008; 983

Harber et al., 2005; Morens et al., 2003; Pacy et al., 1994; Price et al., 1994). 984

The branched chain amino acids (BCAA) (leucine, valine, isoleucine), particularly leucine, have been 985

demonstrated to act as a signal for muscle protein synthesis in vitro (Buse and Reid, 1975; Busquets et al., 986

2002; Dardevet et al., 2000; Fulks et al., 1975; Hong and Layman, 1984; Kimball et al., 1998; Kimball et al., 987

1999; Li and Jefferson, 1978; Mitch and Clark, 1984; Mordier et al., 2000; Tischler et al., 1982). In vivo 988

experiments in animal models have been less consistent, but confirm in vitro results that leucine acts as a 989

signal that up-regulates muscle protein synthesis and/or down-regulates muscle protein degradation 990

(Anthony et al., 2000; Dardevet et al., 2002; Funabiki et al., 1992; Guillet et al., 2004; Layman and Grogan, 991

1986; McNurlan et al., 1982; Nagasawa et al., 2002; Rieu et al., 2003). In contrast, there is limited 992

information available on the influence of leucine alone on muscle protein synthesis in humans (Koopman et 993

al., 2005; Nair et al., 1992; Schwenk and Haymond, 1987; Sherwin, 1978; Tessari et al., 1985). At present, 994

there is no convincing evidence that chronic leucine supplementation above the requirement as previously 995

defined at 39 mg/kg body weight per day is efficient in promoting an increase in muscle mass (Balage and 996

Dardevet, 2010; Leenders et al., 2011). Thus, when the intake of protein is at the PRI based on nitrogen 997

balance, and when amino acid requirements are met, an additional intake of leucine has no further effect on 998

muscle mass. 999

The Panel considers that in healthy adults the available data on the effects of dietary protein intake on muscle 1000

mass and function do not provide evidence that it can be considered as a criterion to set a PRI for protein. 1001

There are no data showing that an additional intake of protein would increase muscle mass in different age 1002

groups who are in nitrogen balance, including subjects undertaking endurance or resistance exercise. There 1003

are also no data showing that an additional protein intake would increase muscle growth in children. 1004

5.2.2. Body weight control and obesity 1005

5.2.2.1. Infants 1006

It has been proposed that the well-known difference in growth observed between formula-fed and breast-fed 1007

infants may be related to differences in protein intake estimated to be 1.4-1.8 times higher per kg body 1008

weight in formula-fed infants compared to breast-fed infants (Alexy et al., 1999). In addition, it has been 1009

suggested that a higher protein intake may contribute to an enhanced insulin secretion and release of insulin-1010

like growth factor (IGF)-1 and IGF-binding protein (IGFBP)-1, which was observed in prospective feeding 1011

studies with infant formulae of different protein content (13, 15 or 18 g protein/L) and a breast-fed control 1012

group (Axelsson, 2006). 1013

In a double-blind, randomised controlled manner the European Childhood Obesity Project explored whether 1014

two types of infant formulae (standard infant formula and follow-on formula) with either lower or higher 1015

protein content (1.8 vs. 2.9 g/100 kcal for infant formula and 2.2 vs. 4.4 g/100 kcal for follow-on formula, all 1016

complying with European regulatory standards) fed during the first year of life resulted in different growth in 1017

the first two years of life (Grote et al., 2010; Koletzko et al., 2009). A reference group of breast-fed infants 1018

was also studied. The mean weight attained at 24 months was 12.4 kg and 12.6 kg for the lower- and higher-1019

protein groups, respectively; the adjusted z-score for weight-for-length was 0.20 (95% CI 0.06–0.34; 1020

p=0.005) higher in the higher-protein formula group than in the lower-protein formula group. Children fed 1021

lower-protein formula did not differ from breast-fed children with respect to weight-for-length and BMI, but 1022

weight and length were higher. Whether this statistically significant but small difference in growth observed 1023

in infants fed higher-protein formula persists and is related to obesity risk in later life is the subject of 1024

ongoing investigations. Currently, these preliminary results do not allow conclusions to be made on the 1025

effects of protein intake with regard to obesity development. 1026

The Panel considers that the results from these studies are not suitable for the derivation of a PRI or a UL for 1027

protein for infants and children. 1028

Dietary reference values for protein

EFSA Journal 20xx;xxxx 27

5.2.2.2. Adults 1029

Controlled studies in humans have investigated whether an increase in protein intake (as E%) ad libitum 1030

induces a decrease in body weight and adiposity. However, these studies are difficult to interpret with respect 1031

to whether the effects observed are due to an increase in dietary protein intake or to the concomitant 1032

modification of carbohydrate and/or fat intakes, and whether any observed effect of an increase in dietary 1033

protein intake would be sustainable (Brehm et al., 2003; Foster et al., 2003; Larsen et al., 2010; Samaha et 1034

al., 2003; Skov et al., 1999b; Weigle et al., 2005; Westerterp-Plantenga et al., 2004; Yancy et al., 2004). A 1035

recent review of the literature concluded that there is strong and consistent evidence that when calorie intake 1036

is controlled, the macronutrient proportion of the diet is not directly related to weight loss (DGAC, 2010). 1037

The Panel considers that these data cannot be used to derive a PRI for protein for adults. 1038

5.2.3. Insulin sensitivity and glucose control 1039

Contradictory results have been obtained for the effects of an increase in protein intake above the PRI on 1040

insulin sensitivity and glucose tolerance. Some human studies showed no effects of a high protein intake on 1041

insulin sensitivity and glucose tolerance (Kitagawa et al., 1998; Tsunehara et al., 1990), but a high protein 1042

intake was found to be accompanied by an increased insulin secretion and demand (Linn et al., 2000). In 1043

other studies, a high protein intake was shown to improve insulin sensitivity and glucose tolerance in humans 1044

(Baba et al., 1999; Gannon et al., 2003; Layman et al., 2003; Piatti et al., 1994; Sharman et al., 2002; Volek 1045

et al., 2002) and animals (Karabatas et al., 1992; Lacroix et al., 2004; Wang et al., 1998). A beneficial effect 1046

of a high-protein diet on insulin resistance and glucose homeostasis has also been reported with a reduced 1047

calorie diet, regardless of weight loss (Farnsworth et al., 2003). In contrast, studies conducted in vitro or in 1048

animal models suggested that exposure to high levels of branched chain amino acids could have a deleterious 1049

effect on insulin signalling, leading to impaired insulin sensitivity and impaired glucose tolerance (Nair and 1050

Short, 2005; Patti et al., 1998; Tremblay and Marette, 2001). This was also suggested by a human cohort 1051

study with a follow-up of 12 years showing that high blood levels of five branched-chain and aromatic amino 1052

acids (isoleucine, leucine, valine, tyrosine and phenylalanine), which are known to be modified by amino 1053

acid profiles of the diet, were significantly associated with future diabetes (Wang et al., 2011). In contrast, 1054

prolonged leucine supplementation (7.5 g/d) in elderly type 2 diabetics habitually consuming an adequate 1055

amount of dietary protein did not modulate their glycaemic control (Leenders et al., 2011). 1056

The Panel considers that these data cannot be used to derive a PRI or a UL for protein for healthy subjects. 1057

5.2.4. Bone health 1058

Protein and calcium are main components of bone structure, and it is widely accepted that protein deficiency 1059

increases the risk of bone fragility and fracture (Dawson-Hughes, 2003; Hannan et al., 2000; Kerstetter et al., 1060

2000; Munger et al., 1999; Promislow et al., 2002; Skov et al., 2002; Zernicke et al., 1995). In several 1061

epidemiological studies, bone mineral density is positively related to protein intake (Chiu et al., 1997; 1062

Cooper et al., 1996; Devine et al., 2005; Geinoz et al., 1993; Hannan et al., 2000; Lau et al., 1998;

1063

Promislow et al., 2002; Teegarden et al., 1998; Tucker et al., 2001). 1064

Although protein is essential for bone health, it has been observed that an increase in protein intake could 1065

also be associated with an increase in urinary calcium excretion. It was first hypothesised that this could 1066

originate from an activation of bone resorption in order to provide calcium for the neutralisation of the acid 1067

load produced by the oxidation of sulphur amino acids (Barzel and Massey, 1998). However, an increase in 1068

protein intake is often associated with an increase in calcium intake (Heaney, 1998), and also induces an 1069

increase in calcium absorption (Kerstetter et al., 1998, 2003) that can be related to the increased urinary 1070

calcium. In addition, the regulation of body acid load is a complex process in which urinary acidity is not 1071

directly related to blood acidity; moreover, the theory that considers bone mineral mobilisation as the main 1072

physiological system involved in the regulation of extracellular hydrogen ion concentration is questionable 1073

since it does not take into account the major role of both the respiratory and the renal tubular systems in this 1074

regulation (Fenton et al., 2009).

Some studies have shown a positive relationship between protein intake and 1075

the risk of bone fracture (Abelow et al., 1992; Frassetto et al., 2000; Hegsted, 1986), whereas others have 1076

found no clear association (Meyer et al., 1997; Mussolino et al., 1998) or have shown an inverse association 1077

Dietary reference values for protein

EFSA Journal 20xx;xxxx 28

(Munger et al., 1999). Intervention studies did not show clear results of a protein intake above the PRI on 1078

markers of bone formation or resorption (Cao et al., 2011; Darling et al., 2009; Fenton et al., 2009). 1079

The Panel considers that the available evidence is insufficient to be taken into consideration when deriving a 1080

PRI or a UL for protein. 1081

5.2.5. Kidney function 1082

Protein intake is a modulator of renal function and increases the glomerular filtration rate (GFR) (Brändle et 1083

al., 1996). An increase in amino acid catabolism induced by an increase in protein intake increases the 1084

production of amino acid-derived metabolites such as bicarbonate, ammonia and urea which require 1085

elimination from the body, for example via the kidneys. 1086

High protein diets have been found to be associated with increases in blood urea levels and urinary urea 1087

excretion, to promote plasma vasopressin, to increase creatinine clearance, and to result in a transient 1088

increase in kidney size in humans (Brändle et al., 1996; Diamond, 1990; Gin et al., 2000; Jenkins et al., 1089

2001; Lentine and Wrone, 2004; Zeller, 1991) and animals (Dunger et al., 1997; Hammond and Janes, 1998; 1090

Lacroix et al., 2004; Schoknecht and Pond, 1993). High intakes of protein by patients with renal disease 1091

contribute to the deterioration of kidney function, and a reduction of protein intake is usually beneficial to 1092

subjects with renal insufficiency (Klahr et al., 1994; Knight et al., 2003; Maroni and Mitch, 1997), and 1093

possibly also to subjects with microalbuminuria (Friedman, 2004). In contrast, protein intake at the PRI 1094

based on nitrogen balance is not a risk factor for renal insufficiency in healthy subjects (Locatelli et al., 1095

1991; Skov et al., 1999a; Wiegmann et al., 1990). According to the available evidence (WHO/FAO/UNU, 1096

2007), the decline of GFR that occurs with advancing age in healthy subjects cannot be attenuated by 1097

reducing dietary protein intake below the PRI based on nitrogen balance. 1098

As reported in the DRVs for water (EFSA Panel on Dietetic Products Nutrition and Allergies (NDA), 2010), 1099

urine osmolarity is physiologically limited between about 50 and 1,400 mOsm/L, and dehydration of more 1100

than 10 % at high ambient temperatures is a serious risk for a life-threatening heat stroke with elevated body 1101

temperature, inadequate cardiac output leading to reduced perfusion of tissues and eventually to 1102

rhabdomyolysis (i.e. rapid breakdown of skeletal muscle) and organ failure (Bouchama and Knochel, 2002). 1103

This risk is particularly high in infants with gastro-enteritis receiving a formula with a high potential renal 1104

solute load (Fomon, 1993). Water required for the excretion of solutes is determined by the composition of 1105

the diet, and by the concentrating capacity of the kidneys. Because the protein content of the diet is, as a rule, 1106

the main determinant of the potential renal solute load which needs water for excretion, a very high protein 1107

intake (±20 E%, e.g. cow’s milk) with a consecutive increased production of urea can severely impair the 1108

water balance of infants, particularly when no other liquids are consumed and/or extrarenal water losses, for 1109

example through diarrhoea, are increased. 1110

The Panel considers that the available evidence is insufficient to be taken into consideration when deriving a

1111

UL for protein. 1112

5.2.6. Capacity of the urea cycle 1113

It is established that there is adequate capacity in the human metabolism to adapt to a large range of protein 1114

intakes above the PRI based on nitrogen balance. This is mainly due to the adaptation of amino acid 1115

catabolic pathways, and it is established that amino acid oxidation varies at a rate dependent on the habitual 1116

protein intake. The level of protein intake has been evaluated in relation to the capacity of the urea cycle to 1117

control the transfer to urea of ammonia released from amino acid deamination (AFSSA, 2007). They 1118

concluded that for a healthy human adult male, protein intake in the range of 0.83 to 2.2 g/kg body weight 1119

per day (around 10 to 27 E%) is considered as safe, whilst IoM (2005) concluded that the maximum rate of 1120

urea production of a 70 kg male not commonly consuming a high-protein diet corresponds to a protein intake 1121

of 250 g/d or about 40 E%. 1122

The Panel considers that the available evidence is insufficient to be taken into consideration when deriving a 1123

UL for protein. 1124

Dietary reference values for protein

EFSA Journal 20xx;xxxx 29

5.2.7. Tolerance of protein 1125

IoM (2005) quotes some reports on very high protein intakes up to 35 E% without adverse effects, whereas 1126

acute adverse effects were reported for intakes ≥45 E% and lethal outcomes occurred when such a diet was 1127

consumed by adults for several weeks. In Europe, adult protein intakes at the upper end of the intake 1128

distributions (90-97.5

percentile) have been reported to be between 17 and 25 E% (Appendix 2B). 1129

The available data on the tolerance of dietary protein are not sufficient to derive a UL for protein. 1130

6. Data on which to base dietary reference values (DRVs) 1131

6.1. Protein requirement of adults 1132

The criterion of adequacy for protein intake is the lowest intake that is sufficient to achieve body nitrogen 1133

equilibrium (zero balance), during energy balance. The analysis of available nitrogen balance data performed 1134

by Rand et al. (2003) concluded that the best estimate of average requirement for healthy adults was the 1135

median requirement of 105 mg N/kg body weight per day or 0.66 g protein/kg body weight per day 1136

(N x 6.25). The 97.5

percentile of the population distribution of requirement was estimated as 133 mg N/kg 1137

body weight per day, or 0.83 g protein/kg body weight per day. This quantity should meet the requirement of 1138

most (97.5 %) of the healthy adult population, and is therefore proposed as the PRI for protein for adults. 1139

The protein requirement per kg body weight is considered to be the same for both sexes and for all body 1140

weights. The PRI of 0.83 g/kg body weight per day is applicable both to high quality proteins and to protein 1141

in mixed diets. 1142

6.1.1. Protein requirement of older adults 1143

There is some evidence that protein efficiency and the anabolic response of muscle and bone to dietary 1144

protein is attenuated in elderly people, and can result in loss of bone and muscle, and in significant 1145

morbidity, osteoporosis and sarcopenia, which are degenerative diseases frequently associated with ageing. 1146

As a result, the amount of protein needed to achieve anabolism could be greater than for younger adults, 1147

particularly as a percentage of energy intake. However, no precise data are available for defining a PRI for 1148

older adults. 1149

6.2. Protein requirement of infants and children 1150

The protein requirement of infants and children can be defined as the minimum intake that will allow 1151

nitrogen equilibrium at an appropriate body composition during energy balance at moderate physical 1152

activity, plus the needs associated with the deposition of tissues consistent with growth and good health 1153

(WHO/FAO/UNU, 2007). 1154

The Panel accepted the approach of WHO/FAO/UNU (2007) in which estimates of the protein requirement 1155

from 6 months to adulthood were derived from a factorial model. In selecting values for maintenance and 1156

growth efficiency for ages greater than 6 months, the likelihood that mixed diets consumed after weaning are 1157

utilised less efficiently is taken into account. 1158

An average maintenance value of 0.66 g protein/kg body weight per day was applied to children and infants 1159

aged from 6 months to 18 years. Average daily needs for dietary protein for growth were estimated from 1160

average daily rates of protein deposition, and an efficiency of utilisation of dietary protein for growth of 1161

58 % was assumed. The average requirement was then estimated as the sum of the maintenance and growth 1162

requirements. 1163

The PRI was estimated based on the average requirement plus 1.96 SD; for this, a combined SD was 1164

calculated from the SD for growth for the respective age (see Appendix 3), which was adjusted for efficiency 1165

of utilisation of dietary protein (58 %), and the SD for maintenance (based on a CV of 12 % for all ages). 1166

Dietary reference values for protein

EFSA Journal 20xx;xxxx 30

6.3. Protein requirement during pregnancy 1167

The Panel follows the approach (WHO/FAO/UNU, 2007) in which the additional protein intake needed 1168

during pregnancy was derived from the newly deposited protein, taking into account the efficiency of protein 1169

utilisation and the maintenance costs associated with increased body weight. Mean total protein deposition 1170

and daily protein deposition in each trimester were estimated indirectly from measurements of total body 1171

potassium accretion and calculated for an average weight gain of 13.8 kg (the mid-point of the recommended 1172

weight gain range for women with normal pre-pregnancy weight) (IoM and NRC, 2009; WHO/FAO/UNU, 1173

2007). The efficiency of protein utilisation was taken by the Panel to be 47 %. The maintenance costs were 1174

based upon the mid-trimester gain in maternal body weight and the adult maintenance value of 0.66 g/kg 1175

body weight per day. The PRI was estimated by adding 1.96 SD (with 1 SD calculated on the basis of a CV 1176

of 12 %) to give an additional 1, 9 and 28 g protein/d in the first, second and third trimesters, respectively 1177

(Table 10). 1178

Table 10: Derivation of dietary reference values for protein during pregnancy. 1179

Trimester Mid-

trimester

weight gain

(kg)

Additional

protein for

maintenance

(g/d)

Protein

deposition

(g/d)

Protein

deposition,

adjusted for

efficiency

(g/d)

Additional

protein

requirement

(g/d)

PRI,

additional

intake

(g/d)

1 0.8 0.5 0 0 0.5 1

2 4.8 3.2 1.9 4.0 7.2 9

3 11 7.3 7.4 15.7 23 28

Mid-trimester increase in weight x average requirement (AR) for maintenance of protein for adults of 0.66 g/kg body weight per 1180

day. 1181

Protein deposition adjusted for the efficiency of protein utilisation during pregnancy: 47 %. 1182

Calculated as the average requirement plus allowance for estimated coefficient of variation of 12 %. 1183

6.4. Protein requirement during lactation 1184

The Panel accepted the factorial approach based on milk protein output assessment (from milk volumes and 1185

the content of both protein nitrogen and NPN) and calculation of the amount of dietary protein needed for 1186

milk protein production with an efficiency of utilisation of 47 %. The factor 6.25 was used to convert 1187

nitrogen to protein. The PRI was estimated by adding 1.96 SD (with 1 SD calculated on the basis of a CV of 1188

12 %) to give an additional 19 g protein/d during the first six months of lactation, and 13 g protein/d after six 1189

months. 1190

6.5. Safety of protein intakes above the PRI 1191

A UL cannot be derived. Concerns about potential detrimental effects of very high protein intake remain 1192

controversial. Acute adverse effects have been reported for protein intakes ≥45 E%, but very high protein 1193

intakes up to 35 E% have not been associated with adverse effects in some reports. It can be concluded that 1194

in adults an intake of twice the PRI is safe. Such intakes from mixed diets are regularly consumed in Europe 1195

by some physically active and healthy individuals. Intakes of 3–4 times the PRI have been observed without 1196

apparent adverse effects or benefits. 1197

Data from food consumption surveys show that actual mean protein intakes of adults in Europe are at, or 1198

more often above, the PRI of 0.83 g/kg body weight per day. Protein intakes as high as 1.7 g/kg body weight 1199

per day (95

percentile of the protein intake of Dutch men aged ≥65 years) or 25 E% have been observed 1200

(see Appendix 2B). 1201

In infants, a very high protein intake (±20 E%) can severely impair the water balance, particularly when no 1202

other liquids are consumed and/or extrarenal water losses are increased. Consequently, such high protein 1203

intakes should be avoided in the first year of life. 1204

Dietary reference values for protein

EFSA Journal 20xx;xxxx 31

CONCLUSIONS 1205

The Panel concludes that an Average Requirement (AR) and a Population Reference Intake (PRI) for protein 1206

can be derived for adults, infants and children and pregnant and lactating women based on nitrogen balance 1207

studies and on factorial estimates of the nitrogen needed for deposition of newly formed tissue and for milk 1208

output. The Panel also considered several health outcomes that may be associated with protein intake, but the 1209

available data were considered insufficient to contribute to the setting of Dietary Reference Values (DRVs). 1210

The Panel concludes that the available data are not sufficient to establish a Tolerable Upper Intake Level 1211

(UL) for protein. 1212

Table 11: Summary of dietary reference values for protein. 1213

Age (years) AR

(g/kg bw x d

-1

)

PRI

(g/kg bw x d

-1

)

Reference weight (kg)

PRI

(g/d)

males (m) females (f) m f

0.5 1.12 1.31 8.0 7.5 10 10

1 0.95 1.14 10.0 9.5 11 11

1.5 0.85 1.03 11.5 11.0 12 11

2 0.79 0.97 12.5 12.0 12 12

3 0.73 0.90 15.0 14.0 14 13

4 0.69 0.86 17.5 17.0 15 15

5 0.69 0.85 19.5 19.5 17 17

6 0.72 0.89 22.0 21.5 20 19

7 0.74 0.91 24.5 24.0 22 22

8 0.75 0.92 27.0 27.0 25 25

9 0.75 0.92 30.0 30.5 28 28

10 0.75 0.91 33.0 34.0 30 31

11 0.75 (m), 0.73 (f) 0.91 (m), 0.90 (f) 36.5 37.5 33 34

12 0.74 (m), 0.72 (f) 0.90 (m), 0.89 (f) 41.0 43.0 37 38

13 0.73 (m), 0.71 (f) 0.90 (m), 0.88 (f) 47.0 48.0 42 42

14 0.72 (m), 0.70 (f) 0.89 (m), 0.87 (f) 53.0 50.5 47 44

15 0.72 (m), 0.69 (f) 0.88 (m), 0.85 (f) 58.0 52.5 51 45

16 0.71 (m), 0.68 (f) 0.87 (m), 0.84 (f) 62.5 54.0 54 45

17 0.70 (m), 0.67 (f) 0.86 (m), 0.83 (f) 64.5 54.5 55 45

18-59 0.66 0.83 74.6 62.1 62 52

≥ 60 0.66 0.83 73.5 66.1 61 55

Pregnant women

trimester

+28

Lactating women

0-6 months post

partum

>6 months post

partum

+19

+13

For infants and children, based upon weighted mean body weights (kg) of European children. For children aged 4-17 years, the 1214

body weights given in the table refer to children actually aged 0.5 years older than the age stated, i.e. 4.5 years, 5.5 years, etc. 1215

(SCF, 1993). For adults, based upon weighted median body weights (kg) of European men and women (SCF, 1993). 1216

In addition to the PRI for non-pregnant women. 1217

1218

Dietary reference values for protein

EFSA Journal 20xx;xxxx 32

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APPENDICES 1786

APPENDIX 1A: POPULATION, METHODS AND PERIOD OF DIETARY ASSESSMENT IN CHILDREN AND ADOLESCENTS IN EUROPEAN COUNTRIES 1787

Country Population Dietary method Year of survey Reference

Austria

Boys and girls aged 7-9 years 3-day record 2007 (Elmadfa et al., 2009b)

Boys and girls aged 10-14 years 3-day record 2007 (Elmadfa et al., 2009b)

Boys and girls aged 14-19 years 24-hour recall 2003-2004 (Elmadfa et al., 2009b)

Belgium

Boys and girls aged 2.5-3 years 3-day record 2002-2003 (Huybrechts and De Henauw, 2007)

Boys and girls aged 4-6.5 years 3-day record 2002-2003 (Huybrechts and De Henauw, 2007)

Boys and girls aged 13-15 years 7-day record 1997 (Matthys et al., 2003)

Boys and girls aged 15-18 2 x 24-hour recall 2004 (De Vriese et al., 2006)

Czech

Boys and girls aged 4-6 years 2 x 24-hour recall 2007 (In: Elmadfa et al. (2009a))

Republic

Boys and girls aged 7-9 years 2 x 24-hour recall 2007 (In: Elmadfa et al. (2009a))

Denmark

Boys and girls aged 1-3 years 7-day record 1995 (Andersen et al., 1996)

Boys and girls aged 4-5 years 7-day record 2003-2008 (Pedersen et al., 2010)

Boys and girls aged 6-9 years 7-day record 2003-2008 (Pedersen et al., 2010)

Boys and girls aged 10-13 years 7-day record 2003-2008 (Pedersen et al., 2010)

Boys and girls aged 14-17 years 7-day record 2003-2008 (Pedersen et al., 2010)

Finland

Infants aged 8 months 3-day record 1999 (Lägstrom, 1999)

Children aged 3 years 4-day record 1999 (Lägstrom, 1999)

Children aged 4 years 4 day record 1999 (Lägstrom, 1999)

Children aged 4 years 3-day record 2008 (Kyttälä et al., 2008)

Children aged 6 years 3-day record 2008 (Kyttälä et al., 2008)

France

Boys and girls aged 4-6 years 3 x 24-hour recall 2006-2007 (In: Elmadfa et al., (2009a))

Boys and girls aged 7-9 years 3 x 24-hour recall 2006-2007 (In: Elmadfa et al., (2009a))

Boys and girls aged 10-14 years 3 x 24-hour recall 2006-2007 (In: Elmadfa et al., (2009a))

Boys and girls aged 15-18 years 3 x 24-hour recall 2006-2007 (In: Elmadfa et al., (2009a))

Germany

Infants aged 12 months 3-day record 1989-2003 (Hilbig and Kersting, 2006)

Children aged 18 months 3-day record 1989-2003 (Hilbig and Kersting, 2006)

Children aged 2 years 3-day record 1989-2003 (Hilbig and Kersting, 2006)

Children aged 3 years 3-day record 1989-2003 (Hilbig and Kersting, 2006)

Boys and girls aged 6 years 3-day record 2006 (Mensink et al., 2007)

Boys and girls aged 7-9 years 3-day record 2006 (Mensink et al., 2007)

Boys and girls aged 10-11 years 3-day record 2006 (Mensink et al., 2007)

Boys and girls aged 12 years Dietary history (over the last 4 weeks) 2006 (Mensink et al., 2007)

Boys and girls aged 13-14 years Dietary history (over the last 4 weeks) 2006 (Mensink et al., 2007)

Boys and girls aged 15-17 years Dietary history (over the last 4 weeks) 2006 (Mensink et al., 2007)

Greece

Boys and girls aged 4-5 years 3-day record+24-hour recall / 3-day record 2003-2004 (Manios et al., 2008)

Dietary reference values for protein

EFSA Journal 20xx;xxxx 46

Country Population Dietary method Year of survey Reference

Hungary

Boys and girls aged 11-14 years 3 x 24-hour recall 2005-2006 (Biro et al., 2007; Elmadfa et al., 2009a)

Ireland

Boys and girls 5-8 years 7-day record 2003-2004 Irish Universities Nutrition Alliance, (IUNA) www.iuna.net

Boys and girls 9-12 years 7-day record 2003-2004 Irish Universities Nutrition Alliance, (IUNA) www.iuna.net

Italy

Boys and girls 0-<3 years consecutive 3-day food records 2005-2006 (Sette et al., 2010)

Boys and girls 3-<10 years consecutive 3-day food records 2005-2006 (Sette et al., 2010)

Boys and girls 10-<18 years consecutive 3-day food records 2005-2006 (Sette et al., 2010)

The

Infants aged 9 month 2-day record (independent days) 2002 (de Boer et al., 2006)

Netherlands

Infants aged 12 monts 2-day record (independent days) 2002 (de Boer et al., 2006)

Children aged 18 months 2-day record (independent days) 2002 (de Boer et al., 2006)

Boys and girls aged 2-3 years 2-day record (independent days) 2005-2006 (Ocke et al., 2008)

Boys and girls aged 4-6 years 2-day record (independent days) 2005-2006 (Ocke et al., 2008)

Boys and girls aged 7-9 years 2-day record 1997-1998 (Hulshof et al., 1998)

Boys and girls aged 10-12 years 2-day record 1997-1998 (Hulshof et al., 1998)

Boys and girls aged 13-15 years 2-day record 1997-1998 (Hulshof et al., 1998)

Boys and girls aged 16-19 years 2-day record 1997-1998 (Hulshof et al., 1998)

Norway

Children aged 2 years Food Frequency Questionnaire 1998-1999 (Lande and Andersen, 2005)

Boys and girls aged 4 years 4-day record 2000 (Øverby and Andersen, 2002)

Boys and girls aged 9 years 4-day record 2000 (Øverby and Andersen, 2002)

Boys and girls aged 13 4-day record 2000 (Øverby and Andersen, 2002)

Boys and girls aged 16-19 years Food Frequency Questionnaire 1997 (Johansson and Sovoll, 1999)

Poland

Boys and girls aged 4-6 years 24-hour recall 2000 (In: Elmadfa et al., (2009a))

Boys and girls aged 7-9 years 24-hour recall 2000 (In: Elmadfa et al., (2009a))

Boys and girls aged 10-14 years 24-hour recall 2000 (In: Elmadfa et al., (2009a))

Boys and girls aged 15-18 years 24-hour recall 2000 (In: Elmadfa et al., (2009a))

Portugal

Boys and girls aged 7-9 years 24-hour recall 2000-2002 (Moreira et al., 2005)

Boys and girls aged 13 years 24-hour recall 2000-2002 (Moreira et al., 2005)

Slovenia

Boys and girls aged 14-17 years Food Frequency Questionnaire 2003-2005. (In: Elmadfa et al., (2009a))

Sweden

Boys and girls aged 4 years 4-day record 2003 (Enghardt-Barbieri et al., 2006)

Boys and girls aged 8-9 years 4-day record 2003 (Enghardt-Barbieri et al., 2006)

Boys and girls aged 11-12 years 4-day record 2003 (Enghardt-Barbieri et al., 2006)

Spain

Boys and girls aged 10-14 years 2 x 24-hour recall 2002-2003 (Elmadfa et al., 2009a; Serra-Majem et al., 2007)

Boys and girls aged 15-18 years 2 x 24-hour recall 2002-2003 (Elmadfa et al., 2009a; Serra-Majem et al., 2007)

United

Boys and girls aged 4-6 years 7-day record 1997 (Gregory et al., 2000)

Kingdom

Boys and girls aged 7-10 years 7-day record 1997 (Gregory et al., 2000)

Boys and girls aged 11-14 years 7-day record 1997 (Gregory et al., 2000)

Boys and girls aged 15-18 years 7-day record 1997 (Gregory et al., 2000)

1788

Dietary reference values for protein

EFSA Journal 20xx;xxxx 47

APPENDIX 1B: INTAKE OF PROTEIN AMONG CHILDREN AGED ~1-3 YEARS IN EUROPEAN 1789

COUNTRIES 1790

1791

Country Age

(years)

N Protein

(E%)

Protein

(g/d)

Protein

(g/kg bw x d

-1

)

mean SD P5 – P95 mean SD P5 - P95 mean SD P5 - P95

Infants and young children (both sexes)

Finland

8 mo 215 12 3 25 6

13 mo 449 17 4 42 10

2 years 398 16 3 45 10

3 years 359 15 4 47 12

Germany

12 mo 432 13.2 2.2

18 mo 478 13.9 2.1

2 years 458 13.6 2.2

3 years 427 12.9 2.0

Italy

0-<3 years 52 14.7 4.4 5.7-21.6 41.5 18.0 7.7-71.3 3.64 1.24 1.46-5.58

The Netherlands

9 mo 333 11.8 1.4 10.2-13.7

28.8 6.2 21.4-27.0

12 mo 306 13.7 2.5 10.8-17.0

36.5 8.3 26.8-47.6

18 mo 302 15.0 2.1 12.4-17.7

43.1 6.5 34.9-51.5

Norway

2 years 172 13.4 1.8 47.2 14.2

Young children

Males

Belgium

2.5-3 102 16.2 2.4 62.5 11.3

Denmark

1-3 129 13 52

The Netherlands

2-3 313 13 11-16 44 31-60

Females

Belgium

2.5-3 95 16.7 1.6 57.7 11.3

Denmark

1-3 149 14 54

The Netherlands

2-3 313 13 11-16 43 31-57

1792

P10-P90

1793

1794

Dietary reference values for protein

EFSA Journal 20xx;xxxx 48

APPENDIX 1C: INTAKE OF PROTEIN AMONG CHILDREN AGED ~4-6 YEARS IN EUROPEAN 1795

COUNTRIES 1796

1797

1798

1799

SE;

P2.5-P97.5 1800

1801

Country Age

(years)

N Protein

(E%)

Protein

(g/d)

Protein

(g/kg bw x d

-1

)

mean SD P5 – P95 mean SD P5 - P95 mean SD P5 - P95

Males

Belgium

4-6.5 236 15.4 2.2 58.5 10.0

Czech Republic

4-6 641 14.0 2.2

Denmark

4-5 81 14 2.0 11-18 63 13 44-85

Finland

4 307 15

6 364 16

France

4-6 164 15.5 0.1

Germany

6 106 13.3 1.9 10.3-17.1 55.3 10.8 39.5-76.9

Greece

4-5 356 16.4 2.5

The Netherlands

4-6 327 13 10-16 51 33-70

Norway

4 206 14.2 2.3 52.4 14.5

Poland

4-6 82 11.1 2.3

Sweden

4 302 14.4 2.2 10.9-18.1 55 13 35-77

United Kingdom

4-6 184 12.9 1.8 9.6-16.3

49.0 13.4 25.4-76.8

Females

Belgium

4-6.5 228 15.1 2.0 52.9 10.5

Czech Republic

4-6 446 14.0 2.2

Denmark

4-5 78 14 2.0 12-18 58 14 35-80

Finland

4 307 15

6 349 15

France

4-6 162 15.0 0.2

Germany

6 102 13.6 2.0 11.0-18.5 50.6 12.4 32.1-68.1

Greece

4-5 389 16.3 2.3

The Netherlands

4-6 312 13 10-16 46 32-60

Norway

4 185 14.0 2.2 49.5 11.9

Poland

4-6 84 12.0 2.8

Sweden

4 288 14.4 2.1 11.3-18.1 51 11 34-71

United Kingdom

4-6 171 12.7 2.0 9.4-17.1

44.5 11.1 26.3-66.8

Both sexes

Italy

3-<10 193 15.7 2.3 12.5-19.5 74.1 18.5 46.9-109.4 3.05 1.02 1.57-4.73

Dietary reference values for protein

EFSA Journal 20xx;xxxx 49

APPENDIX 1D: INTAKE OF PROTEIN AMONG CHILDREN AGED ~7-9 YEARS IN EUROPEAN 1802

COUNTRIES 1803

1804

Country Age

(years)

N Protein

(E%)

Protein

(g/d)

Protein

(g/kg bw x d

-1

)

mean SD P5 – P95 mean SD P5 - P95 mean SD P5 - P95

Males

Austria

7-9 146 14.4 2.7

Czech Republic

7-9 940 14.5 2.4

Denmark

6-9 172 14 2.1 10-18 73 19 48-102

France

7-9 160 14.7 0.2

Germany

7-9 321 13.5 2.1 10.4-17.4 62.0 14.0 40.6-87.0

Ireland

5-8 145 13.6 2.0 10.6-17.1 55.3 15.8 33.8-82.8

The Netherlands

7-9 104 13.5 2.7 9.8-18.8 66 15 44-94 2.3 0.7 1.4-3.2

Norway

9 402 14 2 73 21

Poland

7-9 101 11.7 2.8

Portugal

7-9 1541 16.6 3.8

Sweden

8-9 444 15.4 2.3 11.9-19.6 72 17 48-101

United Kingdom

7-10 256 12.4 1.9 9.0-17.1

54.8 12.3 34.5-79.5

Females

Austria

7-9 134 13.5 2.7

Czech Republic

7-9 765 14.5 2.4

Denmark

6-9 151 14 2.0 11-17 63 14 43-90

France

7-9 144 15.0 0.3

Germany

7-9 308 13.6 2.7 9.5-18.5 55.5 14.9 35.6-81.3

Ireland

5-8 151 13.7 2.1 10.3-17.1 51.9 12.8 34.7-73.0

The Netherlands

7-9 134 13.5 2.6 9.9-17.6 61 16 36-90 2.2 0.6 1.4-3.3

Norway

9 408 14 3 63 20

Poland

7-9 103 11.3 2.5

Portugal

7-9 1503 16.6 3.7

Sweden

8-9 445 15.4 2.2 12.1-19.2 65 15 43-92

United Kingdom

7-10 226 12.8 1.9 9.5-16.7

51.2 11.1 29.5-75.2

1805

SE ;

P2.5-P97.5

1806

1807

Dietary reference values for protein

EFSA Journal 20xx;xxxx 50

APPENDIX 1E: INTAKE OF PROTEIN AMONG CHILDREN AGED ~10-14 YEARS AND OVER IN 1808

EUROPEAN COUNTRIES 1809

1810

Country Age

(years)

N Protein

(E%)

Protein

(g/d)

Protein

(g/kg bw x d

-1

)

mean SD P5 – P95 mean SD P5 - P95 mean SD P5 - P95

Males

Austria

10-14 248 14.6 3.2

Belgium

13-15 74 14.7 2.1

Denmark

10-13 164 15 2.3 11-18 79 20 49-109

France

10-14 160 15.5 0.2

Germany

10-11 199 13.8 2.3 10.3-18.1 64.4 16.2 43.1-94.5

12 114 13.3 1.9 10.5-16.5 82.5 29.1 46.2-135.5

13-14 214 13.7 2.3 10.3-17.4 94.0 33.9 47.5-159.6

Hungary

11-14 124 14.6 2.0 89.7 18.9 1.99 0.59

Ireland

9-12 148 13.6 2.4 9.5-18.0 64.2 15.8 40.9-90.9

Italy

10-<18 108 15.6 1.9 12.9-19.2 99.3 26.2 62.8-147.1 1.82 0.59 1.02-3.22

The Netherlands

10-12 112 13.4 2.4 9.2-17.6 74 20 45-110 1.9 0.6 1.0-3.1

13-15 137 13.1 2.4 9.0-17.4 84 22 51-126 1.6 0.5 0.9-2.5

Norway

13 590 15.0 3.0

Poland

10-14 202 11.5 2.8

Portugal

13 987 17.3 2.6

Sweden

11-12 517 15.9 2.7 11.8-20.5 72 19 44-106

Spain

10-14 66 16.9 2.1

United Kingdom

11-14 237 13.1 2.2 8.9-17.6

64 15.4 30.9-93.9

Females

Austria

10-14 239 14.1 3.0

Belgium

13-15 89 15.3 2.5

Denmark

10-13 196 14 2.2 11-18 65 18 36-91

France

10-14 144 15.6 0.2

Germany

10-11 198 13.7 2.4 10.3-18.0 60.7 15.3 32.2-86.4

12 103 13.1 1.9 9.6-16.3 70.4 23.7 36.4-112.0

13-14 230 13.1 2.2 9.7-17.0 73.0 21.7 40.5-115.3

Hungary

11-14 111 13.9 1.9 75.4 15.3 1.73 0.60

Ireland

9-12 150 13.5 2.2 9.8-17.2 55.6 13.4 35.8-80.5

Italy

10-<18 139 15.8 2.2 12.2-19.8 81.8 20.1 49.4-118.7 1.74 0.56 0.97-2.94

The Netherlands

10-12 124 13.0 2.3 9.3-16.6 66 15 45-97 1.7 0.5 1.1-2.4

13-15 117 13.7 2.5 10.1-17.9 70 17 44-101 1.3 0.4 0.8-1.9

Norway

13 515 14.0 3.0

Poland

10-14 202 11.7 2.7

Portugal

13 1053 17.1 2.9

Sweden

11-12 499 15.4 2.7 11.1-20.2 62 17 37-91

Spain

10-14 53 17.6 1.9

United Kingdom

11-14 238 12.7 2.2 9.2-17.9

52.9 13.2 26.9-78.4

1811

SE;

P2.5-P97.5 1812

1813

Dietary reference values for protein

EFSA Journal 20xx;xxxx 51

APPENDIX 1F: INTAKE OF PROTEIN AMONG ADOLESCENTS AGED ~15-18 YEARS AND OVER IN 1814

EUROPEAN COUNTRIES 1815

1816

Country Age

(years)

N Protein

(E%)

Protein

(g/d)

Protein

(g/kg bw x d

-1

)

mean SD P5 – P95 mean SD P5 - P95 mean SD P5 - P95

Males

Austria

14-19 1527 16.1 4.0

Belgium

15-18 405 13.8 2.1

Denmark

14-17 101 15 2.3 11-19 88 28 46-135

France

15-18 181 15.7 0.3

Germany

15-17 294 13.9 2.5 10.6-17.1 116.1 48.2 62.3-201.0

The Netherlands

16-18 142 13.3 2.6 9.0-18.4 90 26 51-134 1.3 0.4 0.7-1.9

Norway

16-19 92 14 114

Poland

15-18 174 12.4 3.0

Slovenia

15-18 1010 15.0 3.0

Spain

15-18 61 17.8 2.6

United Kingdom

15-18 179 13.9 2.5 9.4-19.6

76.5 19.6 45.4-112.2

Females

Austria

14-19 1422 14.7 4.1

Belgium

15-18 401 13.7 2.1

Denmark

14-17 134 14 2.2 11-18 61 21 28-98

France

15-18 222 15.6 0.2

Germany

15-17 317 12.9 2.3 9.6-16.7 75.0 32.3 37.8-125.6

The Netherlands

16-18 139 13.4 2.6 9.0-18.4 72 20 39-108 1.2 0.4 0.7-1.8

Norway

16-19 62 15 80

Poland

15-18 175 12.0 2.9

Slovenia

15-18 1214 14.0 3.0

Spain

15-18 57 18.0 2.5

United Kingdom

15-18 210 13.9 2.5 9.9-18.9

54.8 15.2 26.4-87.4

1817

SE;

P2.5-P97.5 1818

Dietary reference values for protein

EFSA Journal 20xx;xxxx 52

APPENDIX 2A: POPULATION, METHODS AND PERIOD OF DIETARY ASSESSMENT IN ADULTS IN EUROPEAN COUNTRIES 1819

1820

Country Population Dietary method Year of survey Reference

Austria

Males and females aged 19-64 years 24-hour recall 2007 (Elmadfa et al., 2009b)

Males and females aged 65 and over 3-day record 2007 (Elmadfa et al., 2009b)

Belgium

Males and females aged 19-59 years 2 x 24-hour recall 2004 (De Vriese et al., 2006)

Males and females aged 60-75 years 2 x 24-hour recall 2004 (De Vriese et al., 2006)

Males and females aged 75+ years 2 x 24-hour recall 2004 (De Vriese et al., 2006)

Czech

Republic

Males and females aged 19-64 years 24-hour recalls 2000-2001 (Cifkova and Skodova, 2004; Elmadfa et al., 2009a)

Denmark

Males and females aged 18-74 years 7-day record 2003-2008 (Pedersen et al., 2010)

Males and females aged 18-24 years 7-day record 2003-2008 (Pedersen et al., 2010)

Males and females aged 25-34 years 7-day record 2003-2008 (Pedersen et al., 2010)

Males and females aged 35-44 years 7-day record 2003-2008 (Pedersen et al., 2010)

Males and females aged 45-54 years 7-day record 2003-2008 (Pedersen et al., 2010)

Males and females aged 55-64 years 7-day record 2003-2008 (Pedersen et al., 2010)

Males and females aged 65-75 years 7-day record 2003-2008 (Pedersen et al., 2010)

Estonia

Males and females aged 19-64 years 24-hour recall 1997 (Pomerleau et al., 2001)

Males and females aged 19-34 years 24-hour recall 1997 (Pomerleau et al., 2001)

Males and females aged 35-49 years 24-hour recall 1997 (Pomerleau et al., 2001)

Males and females aged 50 -64 24-hour recall 1997 (Pomerleau et al., 2001)

Finland

Males and females aged 25-64 years 3-day record 2002 (Paturi et al., 2008)

Males and females aged 65-74 years 4-day record 2002 (Paturi et al., 2008)

France

Males and females aged 19-64 years 3 x 24-hour recall 2006-2007 (In: Elmadfa et al., (2009a))

Males and females aged 65-75 years 3 x 24-hour recall 2006-2007 (In: Elmadfa et al., (2009a))

Germany

Males and females aged 35-64 years 24-hour recall 1996-1998 (Linseisen et al., 2003)

Males and females aged 19-80 years 24-hour recall + Dietary History 2005-2006 (Anonymous, 2008)

Males and females aged 19-24 years 24-hour recall + Dietary History 2005-2006 (Anonymous, 2008)

Males and females aged 25-34 years 24-hour recall + Dietary History 2005-2006 (Anonymous, 2008)

Males and females aged 35-50 years 24-hour recall + Dietary History 2005-2006 (Anonymous, 2008)

Males and females aged 51-64 years 24-hour recall + Dietary History 2005-2006 (Anonymous, 2008)

Males and females aged 65-80 years 24-hour recall + Dietary History 2005-2006 (Anonymous, 2008)

Greece

Males and females aged 19-64 years FFQ + 24-hour recall in sub group 1994-1999 (In: Elmadfa et al., (2009a))

Males and females aged 65 and over FFQ 1994-1999 (In: Elmadfa et al., (2009a))

Hungary

Males and females aged 18-59 3-day record 2003-2004 (Elmadfa et al., 2009a; Rodler et al., 2005)

Males and females aged 60 and over 3-day record 2003-2004 (Elmadfa et al., 2009a; Rodler et al., 2005)

Dietary reference values for protein

EFSA Journal 20xx;xxxx 53

Country Population Dietary method Year of survey Reference

Ireland

Males and females 18-64 years 7-day record 1997-1999 Irish Universities Nutrition Alliance (IUNA)

Males and females 18-35 years 7-day record 1997-1999 Irish Universities Nutrition Alliance (IUNA)

Males and females 36-50 years 7-day record 1997-1999 Irish Universities Nutrition Alliance (IUNA)

Males and females 51-64 years 7-day record 1997-1999 Irish Universities Nutrition Alliance (IUNA)

Italy

Males and females 18-<65years consecutive 3-day food record 2005-2006 (Sette et al., 2010)

Males and females aged 65 and over consecutive 3-day food record 2005-2006 (Sette et al., 2010)

Latvia

Males and females 19-64 years 24-hour recall 1997 (Pomerleau et al., 2001)

Males and females aged 19-34 years 24-hour recall 1997 (Pomerleau et al., 2001)

Males and females aged 35-49 years 24-hour recall 1997 (Pomerleau et al., 2001)

Males and females aged 50-64 yearsr 24-hour recall 1997 (Pomerleau et al., 2001)

Lithuania

Males and females 19-65 years 24-hour recall 2007 (In: Elmadfa et al., (2009a))

The

Males and Females aged 19-64 years 2-day record 1997-1998 (Hulshof et al., 1998)

Netherlands

Males and Females aged 65 and over 2-day record 1997-1998 (Hulshof et al., 1998)

Males and females aged 19-30 years 2 x 24-hour recall 2003 (Hulshof and Ocke, 2005)

Norway

Males and females aged 19-64 years FFQ 1997 (Johansson and Sovoll, 1999)

Males and females aged 65 and over FFQ 1997 (Johansson and Sovoll, 1999)

Poland

Males and females aged 19-64 years 24-hour recall 2000 (In: Elmadfa et al., (2009a))

Males and females aged 65 and over 24-hour recall 2000 (In: Elmadfa et al., (2009a))

Portugal

Males and females aged 18-64 years FFQ 1999-2003. (Elmadfa et al., 2009a; Lopes et al., 2006)

Males and females aged 65 and over FFQ 1999-2003 (Elmadfa et al., 2009a; Lopes et al., 2006)

Romania

Males and females aged 19-64 years personal interview 2006 (In: Elmadfa et al., (2009a))

Males and females aged 65 and over personal interview 2006 (In: Elmadfa et al., (2009a))

Spain

Males and females aged 18-64 years 24-hour recall 2002-2003 (Elmadfa et al., 2009a; Serra-Majem et al., 2007)

Males and females aged 65-75 years 24-hour recall 2002-2003 (Elmadfa et al., 2009a; Serra-Majem et al., 2007)

Sweden

Males and females aged 17-74 years 7-day record 1997-1998 (Becker and Pearson, 2002)

Males and females aged 17-24 years 7-day record 1997-1998 (Becker and Pearson, 2002)

Males and females aged 25-34 years 7-day record 1997-1998 (Becker and Pearson, 2002)

Males and females aged 35-44 years 7-day record 1997-1998 (Becker and Pearson, 2002)

Males and females aged 45-54 years 7-day record 1997-1998 (Becker and Pearson, 2002)

Males and females aged 55-64 years 7-day record 1997-1998 (Becker and Pearson, 2002)

Males and females aged 65 -74 7-day record 1997-1998 (Becker and Pearson, 2002)

Dietary reference values for protein

EFSA Journal 20xx;xxxx 54

Country Population Dietary method Year of survey Reference

United

Males and females aged 19-64 years 7-day record 2000-2001 (Hendersen et al., 2003)

Kingdom

Males and females aged 19-24 years 7-day record 2000-2001 (Hendersen et al., 2003)

Males and females aged 25-34 years 7-day record 2000-2001 (Hendersen et al., 2003)

Males and females aged 35-49 years 7-day record 2000-2001 (Hendersen et al., 2003)

Males and females aged 50-64 years 7-day record 2000-2001 (Hendersen et al., 2003)

Males and females aged 65+ years 4-day record 1994-1995 (Finch et al., 1998)

1821

Dietary reference values for protein

EFSA Journal 20xx;xxxx 55

APPENDIX 2B: INTAKE OF PROTEIN AMONG ADULTS AGED ~19-65 YEARS IN EUROPEAN 1822

COUNTRIES 1823

1824

Country Age

(years)

N Protein

(E%)

Protein

(g/d)

Protein

(g/kg bw x d

-1

)

mean SD P5 – P95 mean SD P5 - P95 mean SD P5 - P95

Males

Austria

19-64 778 16.8 4.9

Belgium

19-59 413 16.0 3.1

Czech Republic

19-64 1046 14.1 4.0

Denmark

18-75 1569 14 2.3 11-17

87 25 57-118

Estonia

19-64 900 14.7 4.7 1.0 0.6

Finland

25-64 730 16.3 3.5 86 29

France

19-64 852 16.3 0.1

Germany

19-64 4912 14.6 3.2

Greece

19-64 8365 14.1 1.7

Hungary

>18 473 14.7 2.0 102.0 23.6

Ireland

18-64 662 15.5 2.7 11.3-20.4 100.2 26.6 60.6-149.5

Italy

18-<65 1068 16.3 2.2 13.2-20.2 92.6 25.3 56.2-136.1 1.20 0.36 0.71-1.83

Latvia

19-64 1065 13.7 4.2 1.1 0.6

Lithuania

19-65 849 16.5 5.2

The Netherlands

19-64 1836 14.7 3.1

Norway

19-64 1050 16.0 2.0

Poland

19-64 1106 13.5 3.1

Portugal

18-64 917 17.6 2.4

Romania

19-64 177 17.8 3.8

Spain

18-64 718 19.1 99.6

Sweden

17-74 589 16 2 13-19 90 23 55-130

United Kingdom

19-64 833 16.5 3.6 11.3-23.4

88.2 32.7 47.1-135

Females

Austria

19-64 1345 15.4 2.8

Belgium

19-59 460 16.7 3.4

Czech Republic

19-64 1094 14.7 7.7

Denmark

18-75 1785 15 2.4 12-18

67 18 46-91

Estonia

19-64 1115 15.0 4.4 0.9 0.5

Finland

25-64 846 16.5 3.6 63 20

France

19-64 1499 17.0 0.1

Germany

19-64 6016 14.4 2.6

Greece

19-64 12034 14.4 1.7

Hungary

>18 706 14.6 1.9 79.7 18.0

Ireland

18-64 717 15.6 2.9 11.2-20.6 69.8 17.2 43.4-99.0

Italy

18-<65 1245 15.9 2.3 12.4-19.9 76.0 19.5 45.4-108.6 1.25 0.36 0.71-1.90

Latvia

19-64 1234 13.7 4.8

Lithuania

19-65 1087 16.7 6.2 0.9 0.5

The Netherlands

19-64 2112 15.6 3.8

Norway

19-64 1146 16.0 3.0

Poland

19-64 1334 13.1 3.5

Portugal

18-64 1472 19.0 2.4

Romania

19-64 341 17.1 3.6

Spain

18-64 895 19.5 79.7

Sweden

17-74 626 16 2 13-20 73 17 47-102

United Kingdom

19-64 891 16.6 3.5 10.6-24.2

63.7 16.6 29.9-96.0

1825

(Anonymous, 2008);

P10-P90;

SE;

(Hulshof et al., 1998);

P2.5-P97.5 1826

1827

Dietary reference values for protein

EFSA Journal 20xx;xxxx 56

APPENDIX 2C: INTAKE OF PROTEIN AMONG ADULTS AGED ~19-34 YEARS IN EUROPEAN 1828

COUNTRIES 1829

1830

Country Age

(years)

N Protein

(E%)

Protein

(g/d)

Protein

(g/kg bw x d

-1

)

mean SD P5 – P95 mean SD P5 - P95 mean SD P5 - P95

Males

Denmark

18-24 105 15 2.4 11-19 96 28 50-147

25-34 234 14 2.3 11-19 93 25 58-137

Estonia

19-34 396 14.3 4.6 1.0 0.5

Germany

19-24 510 101.8 1.84

51.4-189.0

25-34 690 99.0 1.50

53.2-168.0

Hungary

18-34 136 14.8 2.0 108 23.6

Ireland

18-35 253 14.8 2.6 10.6-19.3 100.8 26.8 58.6-149.4

Latvia

19-34 337 13.5 4.1 1.0 0.5

The Netherlands

19-30 352 14.2 11.5-17.2 98 72-127 1.2 0.39

Sweden

17-24 67 15 2 12-19 92 27 48-144

25-34 128 15 2 12-18 91 21 58-129

United

19-24 108 14.9 2.6 10.2-22.2

77.8 18.9 34.0-111.3

Kingdom

25-34 219 16.5 4.7 10.8-24.2

90.6 51.0 53.8-156.2

Females

Denmark

18-24 150 14 2.2 11-18 66 18 41-98

25-34 340 15 2.4 11-18 70 18 42-99

Estonia

19-34 459 14.6 4.5 1.0 0.5

Germany

19-24 510 65.2 1.00

35.8-106.5

25-34 972 69.6 0.73

40.4-108.5

Hungary

18-34 176 14.4 1.9 81.5 17.4

Ireland

18-35 269 14.7 3.0 10.7-19.9 66.5 17.5 39.0-95.1

Latvia

19-34 342 13.3 5.0 1.0 0.5

The Netherlands

19-30 398 14.8 10.9-19.2 70 49-93 0.98 0.31

Sweden

17-24 70 15 2 12-20 70 19 35-103

25-34 132 16 2 12-20 73 16 49-103

United

19-24 104 15.4 2.5 10.3-23.4

59.9 16.3 22.8-90.0

Kingdom

25-34 210 15.9 3.6 10.4-24.4

58.7 15.7 30.5-90.2

1831

SE;

(Hulshof and Ocke, 2005);

P2.5-P97.5 1832

1833

Dietary reference values for protein

EFSA Journal 20xx;xxxx 57

APPENDIX 2D: INTAKE OF PROTEIN AMONG ADULTS AGED ~35-64 YEARS IN EUROPEAN 1834

COUNTRIES 1835

1836

Country Age

(years)

N Protein

(E%)

Protein

(g/d)

Protein

(g/kg bw x d

-1

)

mean SD P5 – P95 mean SD P5 - P95 mean SD P5 - P95

Males

Denmark

35-44 318 14 2.0 11-18 93 27 55-134

45-54 336 14 2.2 11-18 86 23 50-125

55-64 336 14 2.4 11-19 82 24 49-129

Estonia

35-49 319 14.7 4.8 1.0 0.5

50-64 185 15.4 4.7 1.0 0.5

Germany

35-64

1013 14.8 4.1 89.9 39,7

35-64

1032 14.0 3.9 88.0 36.8

35-50

2079 93.9 0.74

51.0-151.5

51-64

1633 85.7 0.69

47.5-136.6

Hungary

35-59 199 14.7 2.0 104.5 22.6

Ireland

36-50 236 15.9 2.6 12.3-20.8 102.8 28.8 59.6-156.4

51-64 173 16.2 2.7 11.8-21.6 95.8 22.2 65.4-140.6

Latvia

35-49 372 13.8 4.5 1.1 0.6

50-64 356 13.8 4.0 1.0 0.5

Spain

45-64 265 20.0 95.4

Sweden

35-44 143 16 2 13-19 91 22 57-133

45-54 18 16 2 12-20 91 23 63-129

55-64 68 16 2 13-20 85 20 49-118

United

35-49 253 16.7 2.9 12.2-23.1

90.1 23.3 47.7-139.9

Kingdom

50-64 253 17.0 3.4 11.9-25.1

88.8 22.9 41.5-132.3

Females

Denmark

35-44 412 15 2.4 11-19 71 18 44-104

45-54 359 15 2.4 11-19 65 16 39-92

55-64 326 15 2.5 11-19 63 16 40-94

Estonia

35-49 376 15.2 4.5 0.9 0.5

50-64 280 15.3 4.3 0.8 0.4

Germany

35-64

1078 14.5 4.2 65.6 25.6

35-64

898 13.9 4.2 60.9 24.6

35-50

2694 68.9 0.41

39.3-106.7

51-64

1840 67.3 0.49

38.7-105.2

Hungary

35-59 295 14.7 2.0 81.6 17.5

Ireland

36-50 286 15.9 2.6 11.8-20.5

72.4 16.6 48.9-102.2

51-64 162 16.7 2.8 12.3-21.6

70.7 16.9 40.8-99.7

Latvia

35-49 396 13.7 4.4 0.9 0.5

50-64 496 14.0 4.9 0.8 0.4

Spain

45-64 337 20.2 76.4

Sweden

35-44 132 16 2 13-20 71 15 47-98

45-54 153 16 2 13-21 73 17 49-102

55-64 81 17 2 14-21 75 16 49-99

United

35-49 318 16.7 3.5 11.1-24.5

65.1 16.9 29.7-100.3

Kingdom

50-64 259 17.4 3.2 11.6-24.4

67.4 15.9 37.3-99.4

1837

Cohort Heidelberg (Linseisen et al., 2003);

Cohort Potsdam (Linseisen et al., 2003);

(Anonymous, 2008);

SE ;

P2.5-P97.5 1838

1839

Dietary reference values for protein

EFSA Journal 20xx;xxxx 58

APPENDIX 2E: INTAKE OF PROTEIN AMONG ADULTS AGED ~65 YEARS AND OVER IN EUROPEAN 1840

COUNTRIES 1841

1842

Country Age

(years)

N Protein

(E%)

Protein

(g/d)

Protein

(g/kg bw x d

-1

)

mean SD P5 – P95 mean SD P5 - P95 mean SD P5 - P95

Males

Austria

65+ 147 14.9 3.1

Belgium

60-74 416 16.9 2.7

>75 389 16.0 3.2

Denmark

65-75 240 14 2.6 10-18 76 22 44-113

Finland

65-74 229 17.4 3.8

France

65-75 130 16.5 0.2

Germany

65-80 1469 14.5 2.6 77.8 0.59

45.0-119.7

Greece

65+ 2508 14.1 1.7

Hungary

60+ 138 14.8 2.1 91.9 21.7

Italy

65+ 202 15.5 2.0 12.2-18.8 88.2 21.4 55.6-124.5 1.15 0.30 0.70-1.67

The Netherlands

65+ 185 15.5 3,3 10.6-22.0 86 24 48-124 1.1 0.3 0.6-1.7

Norway

65+ 176 16.0 2.0

Poland

65+ 176 13.6 3.3

Portugal

65+ 246 17.5 2.4

Romania

65+ 177 17.2 3.4

Spain

65-75 122 19.5 77.6

Sweden

65-74 65 16 2 13-19 87 24 53-131

United Kingdom

65+ 540 16.1 3.0 10.8-23.0

71.5 17.0 38.5-105.3

Females

Austria

65+ 202 15.0 2.5

Belgium

60-74 406 16.7 2.8

>75 355 17.0 3.8

Denmark

65-75 198 14 2.6 11-19 62 17 36-95

Finland

65-74 234 17.6 3.4

France

65-75 219 17.5 0.3

Germany

65-80 1562 14.4 2.7 61.6 0.45

34.9-91.6

Greece

65+ 3600 14.4 1.8

Hungary

60+ 235 14.5 1.8 76.0 18.5

Italy

65+ 316 15.7 2.4 12.4-19.9 71.4 18.8 41.0-100.7 1.12 0.32 0.63-1.69

The Netherlands

65+ 236 16.7 3.9 11.1-23.4 73 18 44-101 1.0 0.3 0.6-1.6

Norway

65+ 166 17.0 3.0

Poland

65+ 277 13.2 3.5

Portugal

65+ 339 18.7 2.3

Romania

65+ 341 16.3 3.0

Spain

65-75 122 20.2 68

Sweden

65-74 57 16 3 12-22 75 20 41-119

United Kingdom

65+ 735 16.5 3.7 10.7-24.8

56.0 13.4 30.1-84.3

1843

SE;

P2.5-P97.5 1844

1845

Dietary reference values for protein

EFSA Journal 20xx;xxxx 59

APPENDIX 3: CALCULATION OF PRI FOR INFANTS, CHILDREN AND ADOLESCENTS 1846

The PRI for infants from 6 months onwards and children is calculated as follows: 1847

PRI = AR + 1.96 SD

combined

, with the SD

combined

calculated from the formula:

1848

combined

= (√[CV

maintenance

x maintenance requirement]

+ [CV

growth

x growth requirement]

), 1849

Where CV

maintenance

is 0.12, the maintenance requirement is given in Tables 8 and 9, the CV

growth

can be 1850

calculated from the SD for growth given by WHO/FAO/UNU (2007) in Table 29, and the growth 1851

requirement is the rate of protein deposition (see Tables 8 and 9) divided by the efficiency of dietary protein 1852

utilisation. 1853

1854

Dietary reference values for protein

EFSA Journal 20xx;xxxx 60

GLOSSARY/ABBREVIATIONS 1855

AFSSA

Agence Française de Sécurité Sanitaire des Aliments

ANSES

Agence Nationale de Sécurité Sanitaire de l'alimentation, de l'

environnement et du travail

AOAC

American Organization of Analytical Chemists

Average requirement

BCAA

Branched chain amino acid

BMI

Body mass index

Biological value

Body weight

Confidence interval

CIQUAL

Centre d’information sur la qualité des aliments (French data centre on

food quality)

COMA

Committee on Medical Aspects of Food Policy

Coefficient of variation

day

D-A-CH

Deutschland-Austria-Confoederatio Helvetica

DGAC

Dietary Guidelines Advisory Committee

DNA

Deoxyribonucleic acid

DoH

Department of Health

DRV

Dietary reference value

EAR

Estimated average requirement

European Commission

EFSA

European Food Safety Authority

European Union

female

FAO

Food and Agriculture Organisation

GFR

Glomerular filtration rate

IGF Insulin-like growth factor

IGFBP

Insulin-like growth factor-binding protein

Dietary reference values for protein

EFSA Journal 20xx;xxxx 61

IoM

U.S. Institute of Medicine of the National Academy of Sciences

Potassium

male

mTOR

Mammalian target of rapamycin

Nitrogen

NNR

Nordic Nutrition recommendations

NPN

Non-protein nitrogen

NPPU

Net protein postprandial utilisation

NPU

Net protein utilisation

PD-CAAS

Protein digestibility-corrected amino acid score

PER

Protein efficiency ratio

PRI

Population reference intake

RDA

Recommended dietary allowances

RNA

Ribonucleic acid

SACN Scientific Advisory Committee on Nutrition

SCF

Scientific Committee for Food

Standard deviation

UL Tolerable upper intake level

UNU

United Nations University

USDA

United States Department of Agriculture

WHO

World Health Organisation

year

1856