CAMLAW: Complementary and Alternative Medicine Law Blog

L-carnitine not great for athletes, studies suggest

If you're taking L-carnitine to boost your muscles or endurance, think again.

Research on the supplement is mixed:

 ... studies hinting at L-carnitine's promise have encouraged some doctors to prescribe it to a variety of patients. Dr. Mary Hardy, medical director of the Simms/Mann UCLA Center for Integrative Oncology in Los Angeles, sometimes recommends it to cancer patients to combat fatigue and increase energy levels. Dr. Joyce Frye, a professor of family and community medicine at the Center for Integrative Medicine at the University of Maryland School of Medicine in Baltimore, says she recommends the supplement to some of her heart patients.

But neither recommends the supplement to the average athlete looking for an energy boost or greater exercise capacity. "It's kind of a leap, to conclude that it would have a similar effect in healthy people," Hardy says.

Indeed, in the few studies that have investigated L-carnitine's ability to improve endurance in healthy people, results have been mixed. Studies conducted in the 1990s suggested the supplement improved oxygen uptake and power, but more recent studies have not consistently shown any significant difference in performance between athletes who took the supplement and those who did not.

A molecule derived from two amino acids, L-carnitine occurs naturally in the body, where it's made by the liver and the kidneys. Its job is to carry, or "shuttle," fatty acids into cells, where they're burned for energy. Carnitine deficiencies are rare; most people make enough of the molecule on their own. Carnitine also occurs naturally in a variety of foods, including red meat, tempeh, avocados and asparagus.

Getting too much L-carnitine has its drawbacks, says Roger Clemens, a professor of pharmacology at the USC School of Pharmacy, whose research has focused on functional foods, food processing and nutrition. Many supplement makers recommend as much as 3 to 4 grams of L-carnitine a day, but more than that can cause nausea or diarrhea.

These may be side effects that patients with serious disease are willing to endure. But for those after a faster jog around the block, risking diarrhea and nausea -- absent any proof of benefit -- just might not be worth it.

"It's another fad supplement," Haskal says. "It won't hurt the healthy, but it won't help you, either."

So .... caveat emptor.


Michael H CohenMichael H Cohen
The Los Angeles / San Francisco / Bay Area-based Michael H Cohen Law Group provides healthcare legal and FDA legal & regulatory counsel to health & wellness practices and ventures, including health technology companies (medical devices to wearable health and nanotech), healthcare facilities (from medical centers to medical spas), and healthcare service providers (from physicians to psychologists).Our legal team offers expertise in corporate & transactional, healthcare regulatory & compliance, and healthcare litigation and dispute resolution, in cutting-edge areas such as anti-aging and functional medicine, telemedicine and m-health, and concierge medicine.Our Founder, attorney Michael H. Cohen, is an author, speaker on healthcare law and FDA law, and internationally-recognized thought leader in the trillion-dollar health & wellness industry.
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