The Effects of Oral L-Carnitine Supplementation on Physical Capacity and Lipid Metabolism in Chronic Hemodialysis Patients

BACKGROUND It is well known that the physical activity in chronic hemodialysis patients decreases compared to that in normal subjects. In order to investigate the effects of L-carnitine on physical capacity and lipid metabolism, a cardiopulmonary exercise test using a bicycle ergometer was performed before and after 3 months of oral L-carnitine supplementation under double-blind conditions. METHODS AND RESULTS A total of 20 stable outpatients undergoing hemodialysis treatment were randomly divided into 2 groups: controls receiving placebo and patients receiving 900 mg L-carnitine p.o. daily. The levels of free and acyl carnitine increased significantly from 22.9 ± 7.3 to 149.9 ± 51.8 μmol/l and from 16.0 ± 2.8 to 100.3 ± 50.2 μmol/l, respectively, in the L-carnitine group; however, there was no significant change in other plasma lipid profiles. The exercise time was decreased and the heart rate at the anaerobic threshold was increased in the control group 3 months after the study period, but there were no such changes observed in the L-carnitine group. The minute ventilation/CO2 output slope increased significantly from 38.9 ± 7.8 to 43.8 ± 11.8 in the L-carnitine group. It has been speculated that a shift in the energy source occurs from carbohydrate to lipid, in terms of an increase of oxygen demand. CONCLUSION L-Carnitine supplementation might have some beneficial effects on the physical capacity of chronic hemodialysis patients due to the improvement of the lipid metabolism in the muscle.