Sulphur Amino Acid Requirements in Adults >60 Years

This study aims to determine the requirements for the sulphur amino acids in adults over the age of 60 years: 1. the total sulphur amino acid requirement as methionine only. Methionine is an essential amino acid. 2. the minimum methionine requirement as methionine in the presence of excess dietary cysteine. It is known that protein and amino acid metabolism may be altered with age and methionine and cysteine, in particular, may be important in the diet of older adults. Up to 7 different levels of methionine intake as methionine only (no dietary cysteine) and up to 7 different levels of methionine intake in the presence of excess dietary cysteine will be tested in each subject in random order. Each level of intake will involve a 3-day maintenance diet, with measures being collected on the third.