EXCRETION OF ESSENTIAL AMINO ACIDS BY MEN ON A CONTROLLED PROTEIN INTAKE

Abstract

A nutritional project at the Elgin State Hospital (1) provided an opportunity for the study of the excretion of amino acids by a group of twenty men on a controlled protein intake.'Data obtained from such a study might be expected to throw some light on amino acid metabolism and might possibly have some clinical significance.The subjects taking part in this study were a group of male mental patients, with varied and unrelated psychiatric diagnoses, who had been on the controlled diet for a period of 3 years, during which time they had maintained their body weight and nitrogen balance.Frequent analyses of the diet indicated its constant composition with respect to nitrogen and B complex vitamins.Most of the subjects at some time during the period preceding this study had been on a diet which was restricted in thiamine and riboflavin.However, the protein content did not vary, either during the period of restriction or during the subsequent period of supplementation.At the time when the urines were collected for the present study, all the subjects had been on a vitamin-supplemented regime (1) for from 3 to 11 months and were free from any signs of nutritional deficiency.The protein intake during the 3 years preceding the evaluation of amino acid excretion was approximately 55 gm. per man per day.The average caloric intake per day was 2200 calories.Actual food consumption and food rejection were controlled in a diet kitchen especially equipped for this purpose.Approximately half of the protein in the diet was derived from meat.Preliminary microbiological assays for urinary amino acids with Streptocmcus jaecalis R indicated that the amount of "free" amino acid in the urine was in most cases small, and that some urines contained a sub-