American Journal of Clinical Nutrition, Vol 16, 225-228, Copyright © 1965 by The American Society for Clinical Nutrition, Inc.

Further Observations on the Amino Acid Requirements of Older Men

I. Effects of Nonessential Nitrogen Supplements Fed with Different Amounts of Essential Amino Acids

¹ From the Veterans Administration Center and the Departments of Medicine and Biological Chemistry, School of Medicine and the School of Public Health, University of California, Los Angeles, California

Nitrogen balance was measured in six men aged fifty to seventy years who ingested controlled diets containing different amounts of purified essential amino acids in egg pattern proportions. These diets were supplemented with either glycine or a mixture of the nonessential amino acids in quantities which maintained a nitrogen intake of 7 gm. per day. Better nitrogen retention was observed in five of six subjects when nonessential amino acids replaced glycine as the source of supplemental nitrogen. One of four subjects was in nitrogen equilibrium while ingesting a diet containing 1.2 gm. of essential amino acid nitrogen per day; three of four subjects required more than 1.8 gm. per day; all subjects tested were in nitrogen equilibrium on a daily intake of 2.4 gm.