Abstract

1. A continuous 40 d metabolic nitrogen balance study was conducted on twelve young men age years to evaluate the adequacy of a previously determined safe level of protein intake.

2. Subjects were fed on diets which they were habitually accustomed to and which provided a pro 0.75 g protein (N x 6.25)/kg body-weight per d as the safe level and an energy intake level of 0.2 f weight per d. N balances, including an estimate for integumental  losses as well as certain biochemical were determined for the last 5 d of two consecutive 20 d diet periods.

3. Only two of the twelve subjects were observed to be in negative N balance during the final 5 < period. N balance was generally positive at 8-24 (SD 8.61) mg N/kg body-weight, thus confirming of 0.75 g protein/kg body-weight per d as a safe level of protein intake in the majority of the subject