Topic Overview

What are antioxidants?

Antioxidants protect the body from damage caused by harmful molecules called free radicals. Many experts believe this damage is a factor in the development of blood vessel disease (atherosclerosis), cancer, and other conditions.

You are exposed to free radicals:

• Through by-products of normal processes that take place in your body (such as the burning of sugars for energy and the release of digestive enzymes to break down food).
• When the body breaks down certain medicines.
• Through pollutants.

Antioxidants include some vitamins (such as vitamins C and E), some minerals (such as selenium), and flavonoids, which are found in plants. The best sources of antioxidants are fruits and vegetables. You can also find flavonoids in fruits, red wine, and teas. Antioxidant supplements are also available. It is best to obtain antioxidants from a healthy diet.

What are antioxidants used for?

Antioxidants may play a role in the management or prevention of some medical conditions, such as some cancers, macular degeneration, Alzheimer’s disease, and some arthritis-related conditions.

Are antioxidants safe?

Until more studies are done, it is best to get your antioxidants from a diet rich in fruits and vegetables rather than from supplements. Taking supplements in high doses can be harmful. No single antioxidant alone can protect the body. Most people should eat 7 to 10 servings of fruits and vegetables each day.

The U.S. Food and Drug Administration (FDA) does not regulate dietary supplements in the same way it regulates medicines. A dietary supplement can be sold with limited or no research on how well it works.

Always tell your doctor if you are using a dietary supplement or if you are thinking about combining a dietary supplement with your conventional medical treatment. It may not be safe to forgo your conventional medical treatment and rely only on a dietary supplement. Communication is especially important for women who are pregnant or breastfeeding.

When using dietary supplements, keep in mind the following:

• Like conventional medicines, dietary supplements may cause side effects, trigger allergic reactions, or interact with prescription and nonprescription medicines or other supplements you are taking. A side effect or interaction with another medicine or supplement may make your health worse.
• How dietary supplements are manufactured may not be standardized. Because of this, how well they work or any side effects they cause may differ among brands or even within different lots of the same brand. The form of a supplement that you buy in health food or grocery stores may not be the same as the form used in research.
• Other than for vitamins and minerals, the long-term effects of most dietary supplements are unknown.