a diet rich in the amino acid leucine might help prevent the muscle loss that typically comes with aging, new animal research suggests. french researchers found that a leucine-supplemented diet restored a more youthful pattern of muscle-protein breakdown and synthesis to elderly rats. the older animals had shown a tendency toward excessive protein breakdown before going on the leucine-rich diet, but the amino acid appeared to erase that imbalance. the findings are published in the december issue of the journal of physiology. leucine is an essential amino acid, which means the body cannot manufacture it and it must be ingested through dietary protein. along with other essential amino acids, leucine helps maintain muscle mass -- which has made leucine-containing supplements a favorite of bodybuilders and athletes. it)s well known that after the age of 40 or so, people gradually lose muscle mass, and it)s thought that an imbalance in muscle-protein synthesis and breakdown is involved. in younger people, this process is typically in balance. for example, research shows that after a meal, muscle-protein breakdown slows, whereas synthesis ramps up in response to the influx of amino acids from food. --more
