Variation in Fasting and Postprandial Amino Acids of Men Fed Adequate or Protein-Free Diets

Abstract

Serum free amino acids were measured in fasting and postprandial blood specimens of men fed formula diets containing 76 g of egg white protein, or none. Variation in serum levels was as large within an individual as between subjects fed the same diets. In the absence of dietary protein, serum essential amino acids were decreased and nonessential amino acids were not. Amino acid levels were decreased 2-3 hr after ingestion of protein-free meals and were unchanged or somewhat lower after consumption of meals containing protein, in comparison to fasting values for the same diets. Serum amino acids characteristic of a dietary treatment were essentially the same in samples taken after only 1 day or up to 18 (protein-free) and 84 days (protein adequate), if due consideration is given to the wide intra- and interindividual variance in levels. Serum amino acid patterns appear to be more characteristic of diet than of short-term nutrition status.