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Carnitine (L-carnitine)

Overview:

Carnitine is a nutrient that helps the body turn fat into energy. It is produced by the body in the liver and kidneys and stored in the skeletal muscles, heart, brain, and sperm.

Usually, the body can make all the carnitine it needs. Some people, however, may be deficient in carnitine because their bodies cannot make enough carnitine or transport it into tissues so it can be used. Some other conditions, such as angina or intermittent claudication, can also cause insufficient carnitine in the body, as can some medications.

Carnitine has been proposed as a treatment for many conditions. Some of the conditions carnitine may help treat are serious, and in those cases the supplement should be taken under the supervision of your doctor, as an adjunct therapy to conventional medicine. For other conditions, such as fatigue or improving exercise performance, carnitine appears safe but seems to have little effect.

Heart Conditions

Angina -- The best evidence for carnitine's use for heart disease is as an addition to conventional treatment for stable angina. Several clinical trials indicate that L-carnitine and propionyl-L-carnitine can help reduce symptoms of angina and improve the ability of those with angina to exercise without chest pain. You should not self-treat chest pain with carnitine, however; see your doctor for diagnosis and conventional treatment, and take carnitine only under your doctor's supervision.
Heart attack -- There is little evidence for using carnitine after a heart attack due to a lack of well-designed studies. Some small studies suggest that people who take L-carnitine supplements soon after a heart attack may be less likely to suffer a subsequent heart attack, die of heart disease, experience chest pain and abnormal heart rhythms, or develop heart failure. However, other studies have found no benefit. Carnitine should be used along with conventional medication under your doctor's supervision.
Heart Failure -- A few small studies have suggested that carnitine (usually propionyl-L-carnitine) can help reduce symptoms of heart failure and improve exercise capacity in people with heart failure. However, more and larger studies are needed to confirm any benefit.

Peripheral Vascular Disease

Decreased blood flow to the legs from atherosclerosis (plaque build up) often causes an aching or cramping pain in the legs while walking or exercising. This pain is called intermittent claudication, and the diminished blood flow to the legs is called peripheral vascular disease (PVD). A number of studies show that carnitine can help reduce symptoms and increase the distance that people with intermittent claudication can walk. Most studies have used propionyl-L-carnitine; it isn't known whether L-carnitine would have the same effect.

Diabetic Neuropathy

When high blood sugar levels damage nerves in the body, especially the arms, legs, and feet, the condition is called diabetic neuropathy. Some small preliminary studies suggest acetyl-L-carnitine may help reduce pain and increase normal feeling in affected nerves. It is also possible that carnitine can help nerves regenerate; however, more and better studies are needed to say for sure.

Exercise Performance

Although carnitine is often taken to improve exercise performance, there is no evidence it works.

Weight Loss

Although L-carnitine has been marketed as a weight loss supplement, there is no scientific evidence to show that it improves weight loss.

Alzheimer's Disease and Memory Impairment

The evidence is mixed as to whether carnitine is useful in treating Alzheimer's disease. Several early studies showed that acetyl-L- carnitine, might help delay the progression of Alzheimer's disease, relieve depression related to senility and other forms of dementia, and improve memory in the elderly. Unfortunately, larger and better-designed studies found no benefit. Taking carnitine for Alzheimer's and other forms of dementia should only be done under the supervision of your doctor.

Kidney Disease and Dialysis

Because the kidneys produce carnitine, kidney disease could lead to a deficiency of carnitine in the body. If you have kidney disease, your doctor may prescribe carnitine; however, do not take it without medical supervision.

Male Infertility

Low sperm counts have been linked to low carnitine levels in men. Several studies suggest that L-carnitine supplementation may increase sperm count and mobility.

Erectile Dysfunction

Preliminary studies suggest propionyl-L-carnitine may help improve male sexual function. One study found that carnitine significantly improved the effectiveness of sidenafil (Viagra) in men with diabetes who had not previously responded to Viagra. More studies are needed, however.

Chronic Fatigue Syndrome (CFS)

Some researchers speculate that chronic fatigue syndrome may be caused by deficiencies in a variety of nutrients, including carnitine. L-carnitine has been compared to a medication for fatigue in a study of 30 people with CFS. Those who took L-carnitine did much better than those who took the medication, particularly after receiving the supplement for 4 - 8 weeks. However, the study was not well-designed, and many of those who took the prescription medication dropped out of the study. More research is needed to determine whether carnitine has any true benefit for CFS.

Peyronie's Disease

Peyronie's disease is characterized by a curvature of the penis that leads to pain during an erection because of blocked blood flow. One promising study compared acetyl-L-carnitine to tamoxifen in 48 men with this condition. Acetyl-L-carnitine worked better than the medication at reducing pain during intercourse and minimizing the curve of the penis. Acetyl-L-carnitine also had fewer side effects than tamoxifen. Although the study results are encouraging, more research is needed.

Hyperthyroidism

Some research suggests that L-carnitine may prove useful for preventing or reducing symptoms of an overactive thyroid, such as insomnia, nervousness, elevated heart rate, and tremors. In fact, in one study, a small group of people with hyperthyroidism had improvement in these symptoms, as well as normalization of their body temperature, when taking carnitine. But a larger, well-designed clinical trial is needed before carnitine can be recommended for hyperthyroidism.

Dietary Sources:

Red meat (particularly lamb) and dairy products are the primary sources of carnitine. It can also be found in fish, poultry, tempeh, wheat, asparagus, avocados, and peanut butter.

Available Forms:

Carnitine is available as a supplement in a variety of forms.

L-carnitine: the most widely available and least expensive
Acetyl-L-carnitine: Often used in studies for Alzheimer's disease and other brain disorders
Propionyl-L-carnitine: Often used in studies for heart disease and peripheral vascular disease.

Avoid D-carnitine supplements; they interfere with the natural form of L-carnitine and may produce undesirable side effects.

In some cases, L-carnitine may be taken by prescription or given intravenously by a doctor.

How to Take It:

Pediatric

Carnitine supplements should only be given to children under a doctor's supervision, after determining that a carnitine deficiency exists.

Adult

Recommended doses of L-carnitine vary depending on the health condition being treated. The usual dose is between 1 - 3 g per day:

Angina and heart failure: 1.5 - 2 g per day
Heart disease: 600 - 1,200 mg three times daily, or 750 mg twice daily
Peripheral vascular disease: 2 - 4 g per day
Diabetic neuropathy: 3 g per day
Male infertility: 300 - 1,000 mg three times daily
Chronic fatigue syndrome: 500 - 1,000 mg three to four times per day
Overactive thyroid: 2 - 4 g per day in two to four divided doses

Precautions:

Because supplements may have side effects or interact with medications, they should be taken only under the supervision of a knowledgeable health care provider.

Side effects are generally mild. High doses (5 or more grams per day) may cause diarrhea. Other rare side effects include increased appetite, body odor, and rash.

People with the following conditions should talk to their doctor before taking carnitine:

Peripheral vascular disease
Hypertension (high blood pressure)
Alcohol-induced liver disease (cirrhosis)
Diabetes
Kidney disease

Possible Interactions:

If you are currently being treated with any of the following medications, you should not use carnitine without first talking to your health care provider.

AZT -- In a laboratory study, L-carnitine supplements protected muscle tissue against toxic side effects from AZT, a medication used to treat HIV and AIDS. Additional studies are needed to confirm whether L-carnitine would also have this effect in people.

Doxorubicin -- Treatment with L-carnitine may protect heart cells against the toxic side effects of doxorubicin, a chemotherapy medication used to treat cancer, without reducing the effectiveness of medication. Always talk to your oncologist before combining any complementary or alternative therapy with chemotherapy.

Isotretinoin -- Isotretinoin (Accutane), a strong medication used for severe acne, can cause abnormalities in liver function, measured by a blood test, as well as high cholesterol and muscle pain and weakness. These symptoms are similar to those seen with carnitine deficiency. Researchers in Greece showed that a large group of people who had side effects from isotretinoin got better when taking L-carnitine compared to those who took a placebo.

Valproic acid -- The anticonvulsant medication valproic acid may lower blood levels of carnitine and can cause carnitine deficiency. Taking L-carnitine supplements may prevent any deficiency and may also reduce the side effects of valproic acid.

Supporting Research:

Arsenian, MA. Carnitine and its derivatives in cardiovascular disease. Progr Cardiovasc Dis. 1997;40:3:265-286.

Benvenga S, Ruggieri RM, Russo A, Lapa D, Campenni A, Trimarchi F. Usefulness of L-carnitine, a naturally occurring peripheral antagonist of thyroid hormone action, in iatrogenic hyperthyroidism: a randomized, double-blind placebo-controlled clinical trial. J Clin Endocrinol Metab. 2001;86(8):3579-3594.

Biagiotti G, Cavallini G. Acetyl-L-carnitine vs tamoxifen in the oral therapy of Peyronie's disease: a preliminary report. BJU Int. 2001;88(1):63-67.

Brass EP, Hiatt WR. The role of carnitine and carnitine supplementation during exercise in man and in individuals with special needs. J Am Coll Nutr. 1998;17:207-215.

Bowman B. Acetyl-carnitine and Alzheimer's disease. Nutr Reviews. 1992;50:142-144.

Carrero JJ, Grimble RF. Does nutrition have a role in peripheral vascular disease? Br J Nutr. 2006 Feb;95(2):217-29. Review.

Carta A, Calvani M, Bravi D. Acetyl-L-carnitine and Alzheimer's disease. Pharmacologic considerations beyond the cholinergic sphere. Ann NY Acad Sci. 1993;695:324-326.

Chung S, Cho J, Hyun T, et al. Alterations in the carnitine metabolism in epileptic children treated with valproic acid. J Korean Med Soc. 1997;12:553-558.

Corbucci GG, Loche F. L-carnitine in cardiogenic shock therapy: pharmacodynamic aspects and clinical data. Int J Clin Pharmacol Res. 1993;13(2):87-91.

Cruciani RA, Dvorkin E, Homel P, Malamud S, Culliney B, Lapin J, Portenoy RK, Esteban-Cruciani N. Safety, tolerability and symptom outcomes associated with L-carnitine supplementation in patients with cancer, fatigue, and carnitine deficiency: a phase I/II study. J Pain Symptom Manage. 2006 Dec;32(6):551-9.

De Vivo DC, Bohan TP, Coulter DL, et al. L-Carnitine supplementation in childhood epilepsy: current perspectives. Epilepsia. 1998;39:1216-1225.

Dyck DJ. Dietary fat intake, supplements, and weight loss. Can J Appl Physiol. 2000;25(6):495-523.

Elisaf M, Bairaaktari E, Katopodis K, et al. Effect of L-carnitine supplementation on lipid parameters in hemodialysis patients. Am J Nephrol. 1998;18:416-421.

Fugh-Berman A. Herbs and dietary supplements in the prevention and treatment of cardiovascular disease. Prev Cardiology. 2000;3:24-32.

Gasparetto A, Corbucci GG, De Blasi RA, et al. Influence of acetyl-L-carnitine infusion on haemodynamic parameters and survival of circulatory-shock patients. Int J Clin Pharmacol Res. 1991;11(2):83-92.

Georgala S, Schulpis KH, Georgala C, Michas T. L-carnitine supplementation in patients with cystic acne on isotretinoin therapy. J Eur Acad Dermatol Venereol. 1999;13(3):205-209.

Head KA. Peripheral neuropathy: pathogenic mechanisms and alternative therapies. Altern Med Rev. 2006 Dec;11(4):294-329. Review.

Hiatt WR, Regensteiner JG, Creager MA, Hirsch AT, Cooke JP, Olin JW, et al. Propionyl-L-carnitine improves exercise performance and functional status in patients with claudication. Am J Med. 2001;110(8):616-622.

Iliceto S, Scrutinio D, Bruzzi P, et al. Effects of L-carnitine administration on left ventricular remodeling after acute anterior myocardial infarction: the L-carnitine Ecocardiografia Digitalizzata Infarto Miocardico (CEDIM) trial. JACC. 1995;26(2):380-387.

Kelly GS. L-Carnitine: therapeutic applications of a conditionally-essential amino acid. Alt Med Rev. 1998;3:345-60.

Kendler BS. Recent nutritional approaches to the prevention and therapy of cardiovascular disease. Prog Cardiovasc Nurs. 1997;12(3):3-23.

Loster H, Miehe K, Punzel M, Stiller O, Pankau H, Schauer J. Prolonged oral L-carnitine substitution increases bicycle ergometer performance in patients with severe, ischemically induced cardiac insufficiency. Cardiovasc Drugs Ther. 1999;13:537-546.

Ott BR, Owens NJ. Complementary and alternative medicines for Alzheimer's disease. J Geriatr Psychiatry Neurol. 1998;11:163-173.

Pettegrew JW, Levine J, McClure RJ. Acetyl-L-carnitine physical-chemical, metabolic, and therapeutic properties: relevance for its mode of action in Alzheimer's disease and geriatric depression. Mol Psychiatry. 2000;5:616-632.

Pizzorno JE, Murray MT, eds. Textbook of Natural Medicine. Vol 1. 2nd ed. Churchill Livingstone; 1999:462-466.

Plioplys AV, Plioplys S. Amantadine and L-carnitine treatment of chronic fatigue syndrome. Neuropsychobiology. 1997;35(1):16-23.

Rathod R, Baig MS, Khandelwal PN, Kulkarni SG, Gade PR, Siddiqui S. Results of a single blind, randomized, placebo-controlled clinical trial to study the effect of intravenous L-carnitine supplementation on health-related quality of life in Indian patients on maintenance hemodialysis. Indian J Med Sci. 2006 Apr;60(4):143-53.

Sachan DA, Rhew TH. Lipotropic effect of carnitine on alcohol-induced hepatic stenosis. Nutr Rep Int. 1983;27:1221-1226.

Sachan DS, Rhew TH, Ruark RA. Ameliorating effects of carnitine and its precursors on alcohol-induced fatty liver. Am J Clin Nutr. 1984;39:738-744.

Shils ME, Olson JA, Shike M, Ross AC. Modern Nutrition in Health and Disease. 9th ed. Baltimore, Md: Williams & Wilkins; 1999: 90-92; 1377-1378.

Sinclair S. Male infertility: nutritional and environmental considerations. Alt Med Rev. 2000;5(1):28-38.

Singh RB, Niaz MA, Agarwal P, Beegum R, Rastogi SS, Sachan DS. A randomised, double-blind, placebo-controlled trial of L-carnitine in suspected acute myocardial infaction. Postgrad Med. 1996;72:45-50.

Sum CF, Winocour PH, Agius L, et al. Does oral L-carnitine alter plasma triglyceride levels in hypertriglyceridemic subjects with or without non-insulin dependent diabetes mellitus. Diabetes Nutr Metab Clin Exp. 1992;5:175-181.

Thal LJ, Carta A, Clarke WR, et al. A 1-year multicenter placebo-controlled study of acetyl-L-carnitine in patients with Alzheimer's disease. Neurology. 1996;47:705-711.

Van Wouwe JP. Carnitine deficiency during valproic acid treatment. Int J Vit Nutr Res. 1995;65:211-214.

Villani RG, Gannon J, Self M, Rich PA. L-carnitine supplementation combined with aerobic training does not promote weight loss in moderately obese women. Int J Sport Nutr Exerc Metab. 2000;10:199-207.

Werbach MR. Nutritional strategies for treating chronic fatigue syndrome. Altern Med Rev. 2000;5(2):93-108.

Winter BK, Fiskum G, Gallo LL. Effects of L-carnitine on serum triglyceride and cytokine levels in rat models of cachexia and septic shock. Br J Cancer. 1995;72(5):1173-1179.

Witte KK, Clark AL. Micronutrients and their supplementation in chronic cardiac failure. An update beyond theoretical perspectives. Heart Fail Rev. 2006 Mar;11(1):65-74. Review.

Witt KK, Clark AL, Cleland JG. Chronic heart failure and micronutrients. J Am Coll Cardiol. 2001;37(7):1765-1774.

Alternative Names: Acetyl-l-carnitine; L-carnitine

Review Date: 6/20/2007
Reviewed By: Steven D. Ehrlich, N.M.D., private practice specializing in complementary and alternative medicine, Phoenix, AZ. Review provided by VeriMed Healthcare Network.

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