The intriguing promise of coenzyme Q10

Coenzyme Q10, a nutrient made by the liver (and found in some foods), was discovered about 40 years ago. Scientists have become increasingly interested in the substance because of its role as an antioxidant and in helping cells produce energy. Last month, researchers at UC San Diego reported that coenzyme Q10 supplements might slow the progression of Parkinson’s disease.

Uses: Because it is crucial to cell energy function, coenzyme Q10 supplements may have broad uses, especially in people whose natural coenzyme Q10 levels are low. This includes individuals with congestive heart failure and other cardiac disorders, inflammatory gum disease and AIDS. The nutrient also has been used by people with cancer to reduce the toxicity of some types of chemotherapy.

Dose: Typically 100 to 300 milligrams a day. Some experts recommend taking the supplement with meals.

Precautions: Coenzyme Q10 appears to be safe, even in doses of 1,200 milligrams a day. It can interact with medications used to treat heart failure, diabetes, kidney or liver problems. Some people have diarrhea, stomach upset and poor appetite from taking the supplements.

Research: There is a great deal of research underway on coenzyme Q10. So far, the best evidence for its use is for congestive heart failure. For other conditions, such as for Parkinson’s disease and for cancer, it is too early to say whether coenzyme Q10 will help. Only a few studies have been done on how the nutrient might affect people with high blood pressure, high cholesterol or angina. Early studies on its ability to improve athletic performance have been unimpressive.

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.