BLOOD AMINO ACID STUDIES: VI. USE OF PLASMA AMINO ACID SCORE FOR PREDICTING LIMITING AMINO ACID(S) IN DIETARY PROTEINS

Abstract

Male weanling rats were offered diets ad libitum 18 hours daily for 4–7 days. Protein sources included whole wheat, oatmeal, corn, rye, rice, millet, pea, soya, chick-pea, lentil, lima bean, navy bean, cottonseed, peanut, sesame, egg, fish, milk, and mixtures of animal and plant proteins. Levels of plasma lysine, methionine, threonine, tryptophan, leucine, and isoleucine were determined, and plasma amino acid (PAA) scores were calculated. The limiting amino acid(s) in each diet according to PAA score was in good agreement with that reported in the literature. These data provide convincing evidence that plasma amino acid levels can be used to determine the limiting amino acid in practical diets.