Ability of 6 grams of nitrogen from a combination of rice, wheat, and milk to meet protein requirements of young men for 4 weeks.

Young men consumed a diet that provided 6.0 g of nitrogen, of which rice, wheat, and milk supplied 33, 38, and 29%, respectively, for 28 days following adjustment. This diet contained amounts of essential amino acids that were at least twice the minimal required amounts reported for men. Mean nitrogen balances in four successive 7-day periods were 0.27 +/- 0.13, 0.25 +/- 0.08, 0.10 +/- 0.07 and 0.24 +/- 0.12 g; and the mean for 28 days was 0.22 +/- 0.05 g. Nitrogen retention did not differ significantly between periods. All men who weighed between 65 and 72 kg retained small amounts of nitrogen but one who weighed 78 kg was in slightly negative balance. The mean balances as reported do not provide an allowance for integumental and other losses. The daily protein intake from these sources, equivalent to 0.5 g/kg of body weight, was a critical level slightly lower than the amount appropriate for long-term maintenance of young men weighing 70 kg.