The Levels of Individual Free Amino Acids in the Plasma of Normal Man at Various Intervals After a High-Protein Meal1

Abstract

The ingestion of 50-60 g of protein by 6 normal adults resulted in increased plasma concentrations of most of the 20 amino acids measured, but the rises did not parallel the relative amino acid composition of the food. The concentrations of valine, leucine and isoleucine rose most markedly, and even after 8 hours were higher than the fasting values. Some of the amino acids, notably alanine and glycine, fell to levels considerably below the fasting values in 6-8 hours. Lysine and arginine were characterized by a marked early rise in concentration followed by a leveling off or a decrease in the levels.