Potent antioxidant may prevent damage to cells

Alpha lipoic acid may be the most potent of the antioxidants, nutrients that help neutralize free radicals and prevent damage to cells. (Free radicals are thought to play a role in many diseases.) A vitamin-like fatty acid that contains sulfur, alpha lipoic acid is made by the body and plays a large role in energy production within cells. It is found in red meat and in small amounts in potatoes, carrots, yams and spinach.

Uses: Unlike vitamins C or E, alpha lipoic acid is both water- and fat-soluble, meaning it works inside cells and within fatty cell membranes. Alpha lipoic acid supplements have been touted as a general preventive and as possible treatments for diabetes, Alzheimer’s disease, age-related macular degeneration, cataracts and HIV.

Dose: Lipoic acid usually is sold in capsules of 100 to 300 milligrams. Doses of 600 milligrams a day are recommended for some ailments, although 30 to 300 milligrams a day are thought to be sufficient for healthy people.

Precautions: The long-term effects of taking alpha lipoic acid supplements are not well understood. Studies have shown that extremely high doses of antioxidants may damage cells in much the same way free radicals do. Doses of up to 600 milligrams a day have been shown to be safe in some studies.

Research: Alpha lipoic acid is not accepted in mainstream medicine as a treatment for any condition. However, the federal government has funded studies examining its effect on cell function among people with HIV and multiple sclerosis.

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