Effect of Certain Factors on Nitrogen Retention and Lysine Requirements of Adult Human Subjects IV. TOTAL NITROGEN INTAKE1

The influence of 12, 9, 6 and 4.5 g of dietary nitrogen on nitrogen retention of young men and women was investigated. The basal diet supplied 4.5 g of nitrogen daily and contained 159 g of white wheat flour, 21 g of cornmeal and purified essential amino acids. A mixture of glycine, glutamic acid and diammonium citrate was added as necessary to increase total nitrogen intake to 6, 9 or 12 g. Mean balances in 2 experiments were significantly higher (P < 0.01, < 0.05) with either 9 or 6 g of nitrogen than with 4.5 g when 700 or 900 mg of lysine were administered but did not differ in another experiment when 1500 mg of lysine were provided. Intakes of 12 or 9 g of nitrogen maintained equilibrium in all subjects but smaller amounts were adequate only for certain individuals. There was no interaction between dietary nitrogen and lysine.