Sarcopenia, age-related muscle loss, is well known as a common result of aging - and the resulting lack of exercise hastens age-related decline in other ways. Scientists have demonstrated in recent years that adding the amino acid leucine to the diet prevents this progression, based upon a theory of age-related defects in protein machinery. Here, ScienceDaily notes a more general dietary theory, that the elderly consume less protein: "Since nutritional studies show that many elderly individuals eat less protein than the average person, researchers have reasoned that if the elderly simply increased their protein intake, they might slow down muscle loss -- as long as old age doesn't inherently interfere significantly with the ability to make muscles out of the protein in food. ... We wanted to know if there is some reason your grandmother's body, for example, can't stimulate muscle growth in response to eating the same protein-rich meal that you eat, which might over time contribute to muscle loss ... older bodies are just as good as young ones at turning protein-rich food into muscle." Which is interesting when compared with several lines of work suggesting that there are age-related issues with the process of building muscle - it goes to show just how much work is left to do in even the seemingly simple aspects of our biochemistry.