Angina is a painful condition not always confined to the heart. A blocked femoral artery can decrease the amount of blood and oxygen destined for leg muscles and cause severe leg pain during even the most modest exercise. Called intermittent claudication, this condition is often misdiagnosed as sciatica or lower back arthritis. An Italian study published in The American Journal of Cardiology shows that taking proprionyl-L-carnitine, a carnitine derivative, can increase exercise tolerance and curtail pain for people suffering from this "angina of the leg."

L-carnitine is a naturally occurring amino acid that transports fat molecules to mitochondria--the energy-producing organelles within cells. Once inside the mitochondria, fat is biochemically transformed into cellular energy. The body manufactures L-carnitine from the amino acids lysine and methionine. Recent evidence, however, suggests that higher amounts of L-carnitine than normally produced in the body can enhance the body's disease defenses. It does this by increasing the ability of cells to make energy. Since claudication may reflect the inability of cells to keep up with metabolic needs, L-carnitine is being studied as a possible treatment.

Study Design
Physicians from 13 Italian medical centers selected 245 patients who had intermittent claudication. During a 24-week period the patients received either a placebo or oral proprionyl-L-carnitine. The initial dose was 500 mg twice/day. If no improvement occurred, the dose was increased incrementally to as high as 3 g/day.

The placebo-treated patients experienced no symptom or overall quality-of-life changes as measured by the McMaster Health Index Questionnaire. They did, however, increase the maximal time that they could walk--illustrating that placebos can "heal" and good science requires double-blind studies.

Unlike the placebo-treated patients, subjects taking proprionyl-L-carnitine experienced significantly less leg pain and greater exercise tolerance. When patients who took proprionyl-L-carnitine were further divided into groups based on symptom severity, those with severe claudication improved more than those whose claudication was mild.

This isn't the first study showing that L-carnitine or related compounds can help treat intermittent claudication. It is, however, the best designed and one of the few to be published in a prestigious U.S. medical journal. It's equally important that Sigma-Tau, a major European pharmaceutical company, funded the study. I think we now have enough evidence to recommend L-carnitine and its derivatives as a standard treatment for intermittent claudication.

L-Carnitine's Therapeutic Range
It's common knowledge among physicians that L-carnitine prevents toxic side effects from valproic acid, a popular anti-epilepsy drug that can interfere with L-carnitine metabolism. And that is just one of the supplement's growing number of promising therapeutic uses. Evidence suggests that L-carnitine and its derivatives can help treat conditions such as congestive heart failure, angina and cardiogenic shock (extreme low blood pressure due to heart failure). Other rare metabolic disorders linked to mitochondrial dysfunction also respond to L-carnitine treatment. Yet another study, discussed in July 1996 NSN, demonstrated that L-carnitine improved sperm quality among infertile men. People suffering from Chronic Fatigue Syndrome may have low blood levels of L-carnitine, while acetyl L-carnitine--another L-carnitine derivative--may provide modest benefit for people with Alzheimer's disease
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L-carnitine is relatively safe at the usual adult treatment dose of up to 1 g three times daily. However, people taking therapeutic doses of L-carnitine certainly need to be under a physician's care. Individuals with kidney disease or metabolic disorders must be cautious when taking L-carnitine. As of now, there is no information about L-carnitine's effect on pregnancy or lactation.

My main concern about recommending L-carnitine is that it often upsets the stomach. I advise my patients to take the supplement with meals, and divide the amount into three instead of two daily doses.

Although L-carnitine is available in natural products stores, I respect Sigma-Tau Pharmaceuticals' decision to offer a pharmaceutical-grade version (CarnitorTM), because they are also funding reliable research and educating physicians. CarnitorTM prescriptions will be covered by most medical plans.

Caution: D,L-carnitine, often sold as BT, is not the same as L-carnitine and is potentially toxic. I recommend avoiding it.

Richard N. Podell, M.D., is clinical professor of family medicine at the UMDNJ-Robert Wood Johnson Medical School in New Brunswick, N.J. and director of the Podell Center for Medical Treatment, Prevention and Natural Healing, in New Providence, N.J.

REFERENCES

Breveti, G., et al. "Effect of proprionyl-L-carnitine on quality of life in intermittent claudication." Am J of Card, 79: 777-80, 1997.

Iliceto, S., et al. "Effects of L-carnitine administration on left ventricular remodeling after acute anterior myocardial infarction: The L-carnitine eocardiografia digitalizzata infarto miocardico (CEDIM) trial." J Amer Col Card, 26: 380-87, 1995.

Vitali, G., et al. "Carnitine supplementation in human idiopathic asthenospermia: Clinical results." Drugs, Exptl. and Clin. Res., 21: 1157-59, 1995.

Pettigrew, J., et al. "Clinical and neurochemical effects of acetyl-L-carnitine in Alzheimer's disease." Neurobiology of Aging, 16: 1-4, 1995.

Murakami, K., et al. "Alterations of urinary acetylcarnitine in valproate-treated rats: The effect of L-carnitine supplementation." J of Child Neur, 7: 404-7, 1997.

Singh, R., et al. "A randomized double-blind, placebo-controlled trial of L-carnitine in suspected acute myocardial infarction." Postgraduate Med J, 71, 1995.

Tripp, M., et al. "Systemic carnitine deficiency presenting as familial endocardial fibroelastosis: A treatable cardiomyopathy." N Eng J of Med, 305: 385, 1982.