In recent Canadian experiments, adding protein to the diets of men above the age of 50, together with weightlifting, improved muscle protein synthesis.
This means they were better able to retain or build muscle, which is difficult for older people. The condition wherein elders lose muscle is called sarcopenia.
This work was done by Stuart Phillips of McMaster University, Ontario, Canada. Phillips explains the building of muscle mass ebbs and flows throughout each day. The ebbs actually allow some muscle breakdown and the flows actually build muscle. The cycle is influenced, among other things, by the intake of protein, which provides amino acids for the body to use as building blocks for protein.
Exercise increases protein synthesis. Age decreases protein synthesis. Exercise alone cannot overcome the effects of age.
Also, decreased protein consumption at one meal or two versus more at another decreases muscle protein synthesis and allows increases in muscle breakdown during the periods between meals. The net result is less muscle mass.
Phillips hypothesizes that increasing the building blocks, meaning the protein, at meals in elderly people might help overcome loss of muscle due to sarcopenia. He chose to experiment with men and he knew that older men needed more protein per pound of body weight than young men to get an equal response in muscle protein synthesis.
He first tested older men with whey protein and had success. Then he found the same thing with beef as the protein source. To accomplish this he fed the test subjects graded amounts of protein -- 0, 2, 4 and 6 ounces of beef. He found 6 ounces of beef was optimal to stimulate muscle protein synthesis whether the study subjects exercised or not.
Stuart also tested beef against a soy-based protein source and found beef was superior in stimulating muscle protein synthesis.
Stuart says nutritional experts around the globe are beginning to realize older adults need more protein on a per-meal basis, and for these reasons attitudes about that are beginning to change. He proposes the current "recommended dietary allowance" for older people may be inadequate.
He and others plan to keep researching the topic.