An amino acid for cardiac health

L-carnitine, an amino acid made in the liver and kidneys, plays an important role in helping cells convert fatty acids into energy. It’s also found in meat, poultry and dairy products and in small amounts in most plants. Babies, unable to synthesize L-carnitine, get it from breast milk.

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Uses: Intravenous L-carnitine is prescribed for people with L-carnitine deficiencies, which are rare genetic disorders. Oral L-carnitine supplements are taken in attempts to manage the symptoms of cardiovascular disease, age-related dementia and diabetes. The supplements are also sometimes taken to improve cholesterol levels and boost immunity.

Dose: For improving cardiovascular health, 500 milligrams to 2 grams a day in tablet or capsule form. Intravenous forms are available by prescription only.

Precautions: L-carnitine supplements can cause nausea, cramps and diarrhea, and pose a small risk of seizures. The amino acid can also reduce the body’s uptake of thyroid hormone, so people with hypothyroidism should check with their doctors before taking the supplement.

Research: Animal and some human research shows L-carnitine can increase levels of HDL, or “good” cholesterol, while lowering LDL, or “bad” cholesterol. Several human studies also suggest that a supplement of the amino acid can improve symptoms in patients with various forms of cardiovascular disease. There’s little evidence to suggest it can help people with Alzheimer’s disease, diabetes or compromised immune systems, though one study has suggested it may improve immunity in people infected with HIV. Current research is investigating whether L-carnitine can combat fatigue in people with cancer.

Dietary supplement makers are not required by the U.S. government to demonstrate that their products are safe or effective. Ask your healthcare provider for advice on selecting a brand.

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-- Elena Conis