Effects of L-Carnitine Supplementation on Metabolic Utilization of Oxygen and Lipid Profile among Trained and Untrained Humans

Abstract

Background: The effectiveness of L-carnitine supplementation has been met with conflicting findings when used by sedentary and athletic adults. Objectives: This study aimed to investigate the acute effects of L-carnitine supplementation on aerobic metabolic efficiency and lipid profiles in sedentary and athletic men. Methods: Fifteen sedentary (20.4 ± 1.5 years) and 15 athletic (21.5 ± 2.4 years) men were studied in durations of control, placebo intake and 2 g of L-carnitine supplementation. Lipid profiles, including triglyceride, cholesterol, high-density lipoprotein (HDL) and very-low density lipoprotein (VLDL), were determined before and 40 min after either the placebo or L-carnitine intake. Oxygen consumption (direct VO2), ventilatory threshold (VT), and running time (RT) were recorded after a submaximal treadmill exercise test. Results: Direct VO2 increased significantly at 80% of maximal heart rate after L-carnitine supplementation in both athletic and sedentary men, whereas, a statistical increase in VT and RT occurred only after L-carnitine use in athletes, when compared to the control and placebo subjects. The sedentary group showed no changes in lipid parameters, but triglyceride levels reduced significantly in the athletes after consuming L-carnitine. Conclusions: Acute L-carnitine supplementation possibly affects exercise performance and triglycerides in athletes rather than sedentary men.

Randomised Clinical Trial of Combined L-Carnitine Supplement and Exercise on Biochemical Markers and Exercise Performance: A Systematic Review

“…(5,28,29,32,35). The effects of L-carnitine supplementation combined with exercise on physiological parameters, sports, and physical fitness have also been studied (5,(31)(32)(33)36). One of these studies investigated the effects of L-carnitine supplementation on cytoplasmic Fatty Acid-Binding Proteins (FABPc) and beta hydroxyacyl-CoA dehydrogenase (β-HAD) expression.…”

“…In other studies who involved athletes, 2000 mg to 4000 mg L-carnitine supplement were prescribed daily combined with aerobic and anaerobic exercises (31)(32)(33)(34)(35)(36). In their studies, Leelarungrayub et al (31) measure lipid profiles including triglyceride, cholesterol, high-density lipoprotein (HDL), and very-low-density lipoprotein (VLDL). Meanwhile, blood lactate and blood glucose by Arazi and Mehrtash (32) and Broad et al (35).…”

“…Table II summarises the effects of L-carnitine intake on exercise performance. Leelarungrayub et al (31) mentioned that the athletic men showed an increase in running time. In elite male artistic gymnasts, acute L-carnitine intake of 3,000 mg daily improves aerobic and anaerobic performance which are high in VO2max, mean and maximum power among the carnitine group compared to the placebo group (32).…”

“…Three studies have shown that acute consumption of L-carnitine has decreased serum lipid profiles and blood glucose levels in the blood (31,34,40). Leelarungrayub et al (31) prescribed 2,000 mg of L-carnitine supplementation and showed a reduction in triglyceride levels among athletic men. However, triglyceride levels remained unchanged in inactive individuals because they had more oxidation.…”