Metabolic Effects of Ingestion of L-Amino Acids and Whole Protein

Abstract

Plasma urea nitrogen, ammonia and amino acid concentrations and urinary nitrogen excretion were measured in 10 males after ingestion of one-third of the recommended dietary allowance (RDA) for protein as (trial 1) an L-amino acid mixture, (trial 2) cottage cheese, (trial 3) a combination of cottage cheese and L-amino acids. Mean changes in total essential plasma amino acids were significantly greater at 15 minutes for trials 1 (314 ± 223 μmol 1−1) and 3 (306 ± 294 umol l−1) vs trial 2 (7 ± 114 umol l−1). Mean changes in plasma urea nitrogen from fasting differed significantly between trials 1 and 3 at 15 minutes (0.51 vs −0.79 mol l−1), 45 minutes (0.26 vs − 0.57 mmol l−1) and 180 minutes (0.68 vs 0.08 mmol 1−1). Mean total change in plasma urea nitrogen concentrations over 3 hours was greater for trial 1 (3.38 mmol l−l) than for trial 3 (− 1.71 mmol l−1). The mean plasma ammonia concentration was significantly greater than fasting (14 pmol 1−1) at 120 minutes (38 μmol l−1) for trial 1 only; total change ...