According to research appearing in the American Journal of Clinical Nutrition (December 2007; Vol 86 pp 1738-44) supplementation with L-carnitine improved cognition, as well as muscle mass in a group of subjects over the age of 100. The subjects of the study were 66 men and women averaging 101 years. They were randomly assigned to receive either a placebo or two grams of l-carnitine for six months.
At the end of the study, the group that received the l-carnitine had an average loss of 1.6 kilograms of fat, compared to a .6 kilogram gain of fat for the placebo group. Muscle mass also increased in the group receiving the carnitine with an average gain of 3 kilograms more than the placebo group. The Mini-Mental State Examination was used to measure cognitive performance; the group receiving the supplement had an average increase of 4.1 points at the end of the study. The placebo group only had a 0.6 point gain. The group receiving the carnitine also experienced less fatigue after physical activity.