Determination of the UL of Leucine in Healthy Elderly Men

Amino acid are the building blocks of the body's protein. Some amino acids, including leucine, cannot be made in the body and must be obtained from diet, these are called essential. With increase in age the body's muscle mass decrease and studies have suggested that dietary supplementation of leucine may have potential health benefits in elderly in regards to prevention of age related loss of lean muscle mass, and thus may help improve the quality of life in elderly. Currently, a safe upper dietary intake level of leucine has not been established for healthy elderly. Prior to exploring whether leucine supplementation will prevent or decrease loss of lean muscle mass in elderly we propose to identify the upper intake of leucine in healthy elderly. The purpose of this study is to determine the tolerable upper intake level (UL) of leucine in healthy elderly men (70 - 75 yrs) The investigators hypothesize that with a careful graded stepwise increase in leucine intake in elderly men, above the Estimated Average Requirement (EAR - 50 mg/kg/d), the body's ability to oxidize/dispose of excess amino acids will reach a maximum. With increased leucine intakes we hypothesize an increase in plasma ammonia concentrations and increases in plasma leucine and urinary leucine excretion.