EFFECT OF SIMULTANEOUS INGESTION OF L-AMINO-ACIDS AND WHOLE PROTEIN ON PLASMA AMINO-ACID AND UREA NITROGEN CONCENTRATIONS IN HUMANS

The effect of whole protein and L-amino acid ingestion on plasma amino acid (PAA) and urea nitrogen (UN) concentrations was investigated. Ten males ingested equivalent amounts of nitrogen as (trial 1) cottage cheese, (trial 2) an L-amino acid mixture, (trial 3) cottage cheese and L-amino acids. Mean changes in total PAA between trials 1 (342-mu-mol/liter) and 2 (719-mu-mol/liter) and trials 1 (342-mu-mol/liter) and 3 (981 mu-mol/liter) at 30 min and trials 1 (547-mu-mol/liter) and 3 (143 mu-mol/liter) at 150 min differed significantly. Mean changes in essential PAA between trials 1 (180-mu-mol/liter) and 2 (420 mu-mol/liter) and trials 1 (180-mu-mol/liter) and 3 (500 mu-mol/liter) at 30 min differed significantly. Mean changes in essential PAA between trials 1 (247-mu-mol/liter) and 3 (334-mu-mol/liter) at 60 min and between trials 1 (252-mu-mol/liter) and 3 (80 mu-mol/liter) at 150 min differed significantly. Mean increments in total and essential PAA were higher and peaked faster but decreased more quickly after trials 2 and 3 than after trial 1. Mean changes in plasma UN did not differ between trials. Ingestion of either L-amino acids, whole protein or the mixture of L-amino acids and whole protein was equally effective in increasing total PAA over 4 hr.