Sixty-six subjects over 100 years of age took part in the study, published in this month's American Journal of Clinical Nutrition , which also reports reductions in fat mass and fatigue during the placebo-controlled, randomised, double-blind, 2-phase study.
"Centenarians are characterised by a general weakness, decreasing mental health, impaired mobility and balance, and poor endurance," wrote the authors, led by Mariano Malaguarnera from the University of Catania.
"Our study indicates that oral administration of levo-carnitine evokes a reduction of total fat mass, increases total muscular mass, and facilitates an increased capacity for physical and cognitive activity, by reducing fatigue and improving cognitive functions." L-Carnitine plays an important role in the production of cellular energy, and is also necessary for the transport of long-chain fatty acids like the omega-3 fatty acids across the membrane of mitochondria, the cell's power stations.
"Among all the substances whose concentration decreases with age, L-carnitine diminution is fundamentally important, given its function in the production of energy," explained the authors.
The researchers recruited 66 men and women with an average age of 101 to take part in the study.
The subjects, showing signs of fatigue after only slight physical activity, were randomly assigned to receive either the daily L-carnitine supplement (two grams, from Sigma Tau) or placebo for six months.
At the end of the study, the researchers report that the supplementation with L-carnitine was associated with significant reductions in fat mass, compared to placebo.
Indeed, the active supplement group lost 1.6 kg of fat mass, while the placebo group gained 0.6 kg.
Total muscle mass in the L-carnitine-supplemented group increased by three kilograms more than the placebo group, report the researchers.
Moreover, measurements of fatigue, obtained from a six-minute walking corridor test, decreased after L-carnitine supplementation.
Cognitive performance, measured using the 30-point Mini-Mental State Examination (MMSE), showed increases of 4.1 points for the L-carnitine group, compared to only 0.6 points on average for the placebo group.
Reductions in mental fatigue were also associated with L-carnitine supplementation.
The researchers noted several limitations with their study including using subjects who displayed signs of mild cognitive deficit, having bad eyesight, hearing or who were illiterate.
They also note that the subjects were assisted by someone at all times.
Despite such limitations, they concluded that the administration of the supplement did produce benefits related to physical and mental performance among a population at great risk of such declines.
Source: American Journal of Clinical Nutrition December 2007, Volume 86, Pages 1738-1744 "L-Carnitine treatment reduces severity of physical and mental fatigue and increases cognitive functions in centenarians: a randomized and controlled clinical trial" Authors: M. Malaguarnera, L. Cammallerie, M.P. Gargante, M. Vacante, V. Colonna, M. Motta