Dietary Reference Intakes (DRI), Report 6, Part 3: Protein and Amino Acids

B. Gassmann, Bergholz-Rehbruecke

Data were collected from nitrogen-balance studies which had been to determine basal or maintenance requirements or to check the adequacy of specific nitrogen intakes in healthy adults. These data were synthesized to characterize the distribution of individual protein requirements, the effects of climate of the study site, adult age, sex, and dietary protein source on individual requirements, and the midpoint of and the variability among the protein requirements of healthy persons.

The meta-analysis of the data leads to new recommendations for dietary reference values, i.e. an EAR and RDA (97.5th percentile) for healthy adults of 105 and 132 mg N x kg-1x d-1 (0.66 and 0.80 g good-quality protein x kg-1x d-1), resp. This is much less than most people usually consume. However, the RDA for protein for pregnant women and for women during lactation (1.1 g x kg-1x d-1 ), representing an increased need during pregnancy and lactation of about 25 g/day, indicates that there may be a greater need during pregnancy and lactation than previously thought and reported in the D-A-CH-reference values.

It is for the first time that intakes for any of the nine indispensable amino acids found in dietary protein are recommended. The estimated average requirements for amino acids have been the basis for amino acid scoring patterns for various age groups based on the recommended intake of dietary protein. The recommended protein digestibility corrected amino acid scoring pattern (PDCAA) for proteins for children from 1 year onward and all older age groups is as follows (in mg/g protein): histidine 18; isoleucine 25; leucine 55; lysine 51; methionine + cysteine 25; phenylalanine + tyrosine 47; threonine 27; tryptophan 7, and valine 32. The scoring pattern developed can be used to evaluate the quality of protein sources. This provides a method to balance intakes of poor quality proteins by vegetarians and others who consume limited quantities of high quality dietary proteins. While an upper limit for total protein in the diet as percent ot total energy intake was calculated at no more than 30 % to decrease the risk of chronic disease, dose-relationships to establish a Tolerable Upper Intake Level (UL) for total protein or for any of the amino acids could not be provided because of insufficient data. EU05/03

Keywords: Dietary Reference Intakes 2002 / protein / amino acids/ methods for estimating protein requirements and indispensable amino acids / new recommended dietary allowances /comparison with German, Austrian, and Swiss (D-A-CH-) reference intakes of nutrients 2000

Sie finden den Artikel in deutscher Sprache in Ernährungs-Umschau 05/03 ab Seite 178.