Produced in the body from L-lysine and L-methionine, the synthesis of L-carnitine requires optimal amounts of other key nutrients including niacin, pyridoxine, vitamin C and iron for synthesis. Following production, L-carnitine is transported to the cardiac and skeletal muscle, where 98% of total body L-carnitine is stored. The heart and skeletal muscles, as well as many other tissues, depend on fatty acid oxidation as a source of energy. L-carnitine is an essential nutrient required for the transportation of long-chain fatty acids into the mitochondrial matrix. Within the mitochondria of each cell, a metabolic process called beta-oxidation occurs, resulting in the production of energy in the form of adenosine triphosphate (ATP). L-carnitine also aids in the transport of short-chain and medium-chain fatty acids out of the mitochondria and aids in the liberation of coenzyme A, an important component of ATP.
Some individuals require supplemental L-carnitine to maintain normal metabolism. In addition, L-carnitine requirements vary under certain conditions. For example, L-carnitine is removed from the circulation during hemodialysis. Impaired L-carnitine synthesis by the kidneys may also contribute to the potential for carnitine deficiency in patients with endstage renal disease undergoing hemodialysis. The U.S. Food and Drug Administration has approved the use of L-carnitine in hemodialysis patients for the prevention and treatment of L-carnitine deficiency. Additionally, certain medications including anticonvulsants and nucleoside analogues used in the treatment of HIV infection, may produce a secondary L-carnitine deficiency. Pivalic acid-containing antibiotics may also produce a secondary L-carnitine deficiency, as may certain chemotherapy agents.
A double-blind, placebo, crossover study found that 2 g of L-carnitine had positive effects and significantly attenuated markers of purine metabolism, free radical formation, muscle tissue disruption, and muscle soreness after physical exertion. A randomized, placebo-controlled study suggested L-carnitine can improve exercise tolerance and muscle strength while decreasing lactic production.
Energy Production and Metabolism
L-carnitine is known to play a central role in metabolism, specifically in the production of energy from fatty acids. Dietary L-carnitine supplementation has been shown to have a metabolic effect, facilitating fatty acid oxidation in overweight animals undergoing rapid weight loss.7 In a human performance controlled trial, a study group given L-carnitine increased their exercise output by 11% from baseline, while the control group showed no change. These changes were also associated with an improvement in exercise performance.
Administration of L-carnitine has been shown to support the health of myocardial tissues in a number of experimental model systems and to improve cardiovascular wellness. In a controlled study of 160 patients, L-carnitine was randomly administered to 81 patients at a dose of 4 g/day for a year. During the study, the patients showed an improvement in heart rate, maintained healthy blood pressure, heart rhythm and myocardial contractility, while demonstrating a decrease in mortality. In a study of 80 cardiovascular patients, randomly assigned to receive either L-carnitine (2 g/day orally) or placebo, for a mean range of 10 to 54 months, analysis showed that the patients’ survival rate was statistically significant in the L-carnitine group.
† These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
- Natural Standard Database. www.NaturalStandard.com. Accessed February 24, 2012.
- Guarnieri G, Situlin R, Biolo G. Carnitine metabolism in uremia. Am J Kidney Dis 2001;38(4 Suppl 1):S63-67.
- From:http://lpi.oregonstate.edu/infocenter/othernuts/carnitine/. Accessed 3-17-14.
- Ho JY1, Kraemer WJ, Volek JS, Fragala MS, Thomas GA, Dunn-Lewis C, Coday M, H kkinen K, Maresh CM. l-Carnitine l-tartrate supplementation favorably affects biochemical markers of recovery from physical exertion in middle-aged men and women. Metabolism. 2010 Aug;59(8):1190-9.
- Borghi-Silva A1, Baldissera V, Sampaio LM, Pires-DiLorenzo VA, Jamami M, Demonte A, Marchini JS, Costa D. L-carnitine as an ergogenic aid for patients with chronic obstructive pulmonary disease submitted to whole-body and respiratory muscle training programs. Braz J Med Biol Res. 2006 Apr;39(4):465-74.
- Volek JS1, Kraemer WJ, Rubin MR, G mez AL, Ratamess NA, Gaynor P. L-Carnitine L-tartrate supplementation favorably affects markers of recovery from exercise stress. Am J Physiol Endocrinol Metab. 2002 Feb;282(2):E474-82.
- Center SA1, Warner KL, Randolph JF, Sunvold GD, Vickers JR. Influence of dietary supplementation with (L)-carnitine on metabolic rate, fatty acid oxidation, body condition, and weight loss in overweight cats. Am J Vet Res. 2012 Jul;73(7):1002-15.
- Wall BT1, Stephens FB, Constantin-Teodosiu D, Marimuthu K, Macdonald IA, Greenhaff PL. Chronic oral ingestion of L-carnitine and carbohydrate increases muscle carnitine content and alters muscle fuel metabolism during exercise in humans. J Physiol. 2011 Feb 15;589(Pt 4):963-73.
- Lopaschuk G. Regulation of carbohydrate metabolism in ischemia and reperfusion. Am Heart J. 2000 Feb;139(2Pt 3):S115-9.
- Davini P1, Bigalli A, Lamanna F, Boem A. Controlled study on L-carnitine therapeutic efficacy in post-infarction. Drugs Exp Clin Res. 1992;18(8):355-65.
- Rizos I. Three-year survival of patients with heart failure caused by dilated cardiomyopathy and L-carnitine administration. Am Heart J. 2000 Feb;139(2 Pt 3):S120-3.
Always be sure to speak with your healthcare provider before starting any new nutritional supplement when pregnant or nursing. For children, we recommend speaking with your child's pediatrician regarding proper dosing. Store away from children.