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October 12, 2010 | Comments: 3

Carnitine Claims: Real or Hyped?

Many claims are made for carnitine—that it can treat heart disease, boost energy, improve memory, and promote weight loss, for example. But that doesn’t mean you need a supplement.

Our bodies make carnitine from amino acids, which are building blocks of protein. Carnitine plays a crucial role in the mitochondria—the energy-producing structures in cells—and in muscles, including heart muscle. It also acts as an antioxidant. Most of the theories about how supplemental carnitine may help improve health start with the fact that as we age, carnitine levels drop and mitochondrial function becomes impaired. This may contribute to some adverse effects of aging—such as declines in energy, muscle strength, and brain function—as well as to some diseases. Thus, high doses of carnitine may help prevent or reverse some of these problems in the mitochondria and elsewhere. That’s the hope, at least.

Clinical research on carnitine is in its infancy, but studies have yielded some promising results.

• Cardiovascular disease and diabetes. Studies suggest carnitine may help prevent or reduce the damage from heart attacks; reduce the risk of angina, heart failure, and death in cardiac patients; and reduce oxidation of LDL (“bad”) cholesterol (oxidation makes LDL more damaging to arteries). Other studies found that in people with diabetes, carnitine can improve insulin sensitivity and help treat diabetic complications, though sometimes the carnitine was administered intravenously.

• Brain. Research has yielded mixed results. A 2003 British analysis of 21 studies concluded that carnitine may benefit people suffering from mild cognitive impairment and early Alz­heimer’s, but a review by the Cochrane Collaboration, also in 2003, found the evidence unconvincing.

• Healthy aging. An Italian study in 2008 found that carnitine reduced physical and mental fatigue in people over 70. A year earlier another Italian study concluded that carnitine could reduce fatigue and improve cognitive function in centenarians.

• Exercise performance and weight loss. Twenty years of research has been unable to prove any benefits in these two areas.

Still too soon to act

Despite some promising research on carnitine, we cannot advise taking supplements until larger, longer, well-designed studies in people are done. Most marketing claims are overblown. No one knows what dose should be used for what ailment or which form of carnitine is best.

Don’t fall for claims that carnitine will improve your athletic performance or make you lose weight. Don’t take it for a medical condition such as heart disease without talking to your doctor first. As with all dietary supplements, you don’t know what you’re getting in the bottle, which can cost $20 to $40 for a month’s supply. Carnitine may interfere with sleep if taken in the evening. It appears to be safe, though the long-term effects of large doses are unknown.

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