L-Carnitine reduces physical and mental fatigue, improves cognitive function in centenarians

A report published in the December, 2007 issue of the American Journal of Clinical Nutrition described the results of a study conducted by Italian researchers which found a positive effect for L-carnitine (levo-carnitine) on energy levels and cognitive function in individuals 100 years of age and older. The age-related decline in L-carnitine, which plays a role in cellular energy metabolism, could be involved in the fatigue experienced by many older individuals.

Twenty-four men and forty-six women aged 100 to 106 who reported experiencing fatigue after even slight physical activity were randomized to receive 2 grams L-carnitine per day or a placebo for six months. Physical examinations at the beginning and end of the treatment period determined the participants' body mass index, total fat mass and muscle mass. Blood samples were drawn monthly and analyzed for cholesterol, carnitine levels and other factors. Mental and physical fatigue was scored, and cognitive function was evaluated before and after the treatment period. Physical activity was assessed each week with a six minute walking test.

There were three deaths among the group that received L-carnitine and five in the placebo group over the course of the study. The group that received L-carnitine experienced an increase in plasma carnitine concentrations. They also experienced lower total cholesterol, significant reduction of fat mass, gains in total muscle mass, a reduction in physical and mental fatigue and fatigue severity, and better cognitive function scores compared with those received a placebo. Additionally, walking capacity improved in the carnitine group.

Because L-carnitine is necessary for mitochondrial long-chain fatty acid oxidation, an elevation in carnitine levels could increase the fatty acid oxidation rate, thereby lowering glucose utilization, preserving muscle glycogen, and ensuring optimal production rates of oxidative adenosine triphosphate (ATP, which releases energy in the cell). "Our study indicates that oral administration of levo-carnitine produces 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," the authors conclude.