One of the most versatile nutraceuticals for a number of clinical applications is Carnitine. Carnitine, a vitamin-like compound, is generally classified as an amino acid. Not to be confused with Carnosine, L Carnitine (Levocarnitine), is the preferred form (isomer) of Carnitine. Another form of Carnitine, the D-isomer, or D Carnitine, is not biologically active. D Carnitine can compete with the L-isomer. Always look for a guarantee that your Carnitine product is free of D Carnitine. Acetyl L-Carnitine (ALCAR), the acetyl derivative of L-Carnitine, and a popular supplement for supporting brain function, is metabolized in the body from carnitine, crosses the blood brain barrier more effectively and is best known for its brain protection and performance benefits. For the purposes of expanding the benefits of carnitine for energy and performance enhancement, we will stick to L carnitine in this article.
Carnitine facilitates a fundamental role in energy metabolism. Carnitine mediates the transport of fatty acids into the mitochondria-our cellular energy production furnaces where fat and carbohydrate metabolism for energy occurs. It also supports cellular elimination of waste products produced in energy metabolism. Energy in, toxins out-this has been referred to as “the carnitine shuttle.” Carnitine is studied extensively in part because of the important role it plays in fatty acid oxidation-the utilization of fats for energy production. Fatty acids are one of the primary energy sources for the body. Because of carnitine’s fundamental role in energy metabolism, it is concentrated in tissues that utilize fatty acids as their primary dietary fuel, such as skeletal and cardiac (heart) muscle. Muscles have a high demand for carnitine during prolonged exercise, and fats can account for up to 2/3rds of the energy burned. Most individuals think of carbohydrates and blood sugar, and stored carbohydrate reserves, called glycogen, as the fuel that feeds the energy machinery of our body. However, fat stores, in the form of triglycerides in fat cells, store the majority of the energy that is used by the body. All of the fat stores in the human body account for at least 50% of the energy contribution when we are resting, and can provide an even larger portion once we start doing extended physical activity. During exercise, we use a combination of these energy sources. During high intensity exercise, the main source of energy is carbohydrate and at a lower intensity and in prolonged exercise, fat is the predominate source. Think of sprinting as fast as you can, as a high intensity exercise. As there is a limit to the amount of carbohydrate that can be stored in the muscles, high intensity work can only be sustained for short periods. During more prolonged exercise, say a marathon or cross country skiing, the body relies on fat as it’s primary source of energy substrate. We have large stores of fat so low intensity work can be maintained for long periods. Clearly, carnitine is essential for the utilization of fats in energy metabolism. A lesser known aspect of carnitine, is its benefit to carbohydrate energy metabolism.(1) Studies on the carbohydrate and fatty acid metabolism in heart function, reveals that carnitine enhances glucose metabolism, both in the normal working heart muscle, and in recovery from cardiac events.(2) Since fat metabolism is so important to energy production, carnitine supplementation would be a logical choice for enhancing energy metabolism during both relatively high intensity and in low intensity exercise. A review of the research literature indicates carnitine benefits resistance exercise(3), reduces the amount of exercise-induced muscle tissue damage, and promotes recovery. There is research as well demonstrating the benefits of carnitine for endurance exercise(4), although in all fairness, I will report that there are some studies that fail to demonstrate a positive outcome. Nevertheless, clinically I and many of my colleagues, can report that carnitine supplementation provides benefits for any type of exercise and for energy enhancement in general. Apart from the role of carnitine in athletic performance, and cardiovascular function, carnitine improves energy levels in fatigue disorders and in degenerative diseases such as AIDS, Multiple Sclerosis(5) and cancer. Carnitine deficiency, and impaired mitochondrial function, is considered to be a primary cause of fatigue in these conditions. In several Chronic Fatigue Syndrome studies, carnitine supplemention, improved outcomes. In one trial with CFS patients, L-Carnitine was found to be more helpful in improving mental and physical fatigue symptoms in patients than amantadine, a drug used to treat multiple sclerosis-related fatigue.(6) Fatigue is a common side effect in cancer patients, resulting from chemotherapy, radiation treatment and poor nutritional status. Carnitine deficiency is one of the nutrients that may contribute fatigue problems in degenerative diseases. In a recent controlled trail, supplementing with carnitine resulted in improvement of fatigue. Secondary outcomes included reduced depression, and overall improvement in the quality of life and performance status.(7)
Dietary sources of carnitine include foods of animal origin, such as meat and dairy products, making carnitine supplementation, desireable for vegans. Only about a quarter of the carnitine supplied by food is absorbed. The body also synthesizes carnitine from the amino acids methionine and lysine. Robert Crayhon, author of The Carnitine Miracle, a resource I highly recommend for a more thorough review of the benefits of carnitine writes: “the Stone Age hunter probably got at least 500 mg of carnitine a day, and possibly as much as 2 grams. Today the average carnitine intake is estimated at a mere 30 to 50 mg a day- hardly anyone gets the 250 to 500 mg of carnitine per day that is regarded as optimal (with more needed under stress and other special circumstances). In order to get 500 mg, we would have to consume over two pounds of beef every day”. Without a doubt, if one wants to enhance energy metabolism with carnitine, then supplementation is necessary.
In research studies, 1 to 3 grams has very positive effects on energy enhancement, ameliorating the effects of medications on mitochondrial function, weight loss and in reducing serum triglyceride levels. I can report huge clinical benefits for individuals supplementing with carnitine in doses ranging from 2 to 6 grams and higher in cases where it was well tolerated. One caveat…some individuals will experience bowel disturbance ingesting carnitine in higher doses-it has a laxative effect at varying dosages. I have seen bloating, andominal gas and diarrhea. Other rare side effects include increased appetite, body odor, and rash. It is best to gradually increase your dose of carnitine to bowel tolerance. Start with 500 mg to 1 gram daily, and increase every 3 to 7 days. some may notice an energizing effect already with 1 g of carnitine or, while for others it may take as much as 4 grams of carnitine, or more. Start at the low end and increasing the dose until you feel the difference. Once you have reached doses that deliver the benefits you desire, maintain that level as long as you like. Any carnitine that you do not utilize is excreted by the kidneys where carnitine levels in the body are regulated. Please consult with your doctor if you have kidney disease before using carnitine. Carnitine is actually administered to patients undergoing dialysis,(8) albeit there remains some concern about its safety. With higher doses that may create some bowel disturbance, reduce your dose a little, or stop for a few days until your symptoms disappear. I have found that some experimenting with the right dose will eventually get you to where you can take carnitine regularly and reap some of its benefits.
1. Regulation by carnitine of myocardial fatty acid and carbohydrate metabolism under normal and pathological conditions. Calvani M, Reda E, Arrigoni-Martelli E.
Basic Res Cardiol. 2000 Apr;95(2):75-83.
2. The protective effect of L-carnitine on ischemia-reperfusion heart. Xie J, Zeng Q, Wang L.
J Huazhong Univ Sci Technolog Med Sci. 2006;26(2):188-91 Department of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology , Wuhan, China.
3. L-Carnitine L-tartrate supplementation favorably affects markers of recovery from exercise stress. Volek JS, Kraemer WJ, Rubin MR, Gomez AL, Ratamess NA, Gaynor P.
Am J Physiol Endocrinol Metab. 2002 Feb;282(2):E474-82. Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, Connecticut 06269, USA. firstname.lastname@example.org
4. The effect of L-carnitine supplementation on plasma carnitine levels and various performance parameters of male marathon athletes. Swart, I., et al.
Nutrition Research 17:405-414, 1997.
5.Levocarnitine administration in multiple sclerosis patients with immunosuppressive therapy-induced fatigue. Lebrun C, Alchaar H, Candito M, Bourg V, Chatel M.
Mult Scler. 2006 Jun;12(3):321-4.
Department of Neurology, Hopital Pasteur, 30 voie romaine, 06002 Nice, France.
6. Amantadine and L-carnitine treatment of Chronic Fatigue Syndrome. Plioplys AV, Plioplys S.
Chronic Fatigue Syndrome Center, Mercy Hospital and Medical Center, Chicago, Ill. 60616, USA.
7. Safety, tolerability and symptom outcomes associated with L-carnitine supplementation in patients with cancer, fatigue, and carnitine deficiency: a phase I/II study. Cruciani RA, Dvorkin E, Homel P, Malamud S, Culliney B, Lapin J, Portenoy RK, Esteban-Cruciani N.
J Pain Symptom Manage. 2006 Dec;32(6):551-9.
8. Dialysis-related carnitine disorder and levocarnitine pharmacology. Evans A.