Other name(s):

free radical scavengers

General description

Antioxidants help prevent free radicals from harming healthy cells in the body. They do this by stopping free radicals from being formed. In this way they counteract oxidative stress.

A free radical is an atom or molecule that contains one or more unpaired electrons. These electrons want to bond to atoms or molecules and do so easily. This process harms your body. Many things can cause free radicals. These include radiation, environmental toxins, and tobacco smoke. Your body also makes free radicals when it converts fat to energy.

Antioxidants come in many forms. These include enzymes, vitamins, and minerals.


  • Catalase

  • Coenzyme Q-10

  • Glutathione peroxidase

  • Methionine reductase

  • Superoxide dismutase


  • Beta-carotene

  • Vitamin A

  • Vitamin C

  • Vitamin E


These are not antioxidants on their own. But they work with oxidative enzymes.

  • Selenium

  • Zinc


  • Bilberry

  • Ginkgo biloba

  • Grape seed extract

  • Green tea extract


  • Anthocyanidins

  • Carotenoids

  • Flavonoids

  • Resveratrol

  • Lutein

  • Lycopene

Medically valid uses

Antioxidants have been studied to check how they affect cancer, heart disease, and arthritis. There have also been studies of their impact on diseases due to aging. These include macular degeneration.

The results of these studies have been mixed. Some studies have shown an increase in lung cancer among smokers who took beta-carotene. Another study showed that selenium and vitamin E did not decrease the risk of prostate cancer. It also found that men taking vitamin E alone had an increased risk of prostate cancer.

It also isn’t known if taking manmade (synthetic) antioxidant supplements has the same effect on the body as eating foods rich in these substances. The Women's Antioxidant Cardiovascular Study looked at supplemental vitamin C, vitamin E, and beta-carotene. It found that these didn’t prevent heart disease or stroke in women ages 45 to 65. But it did decrease the risk in women age 65 and older.

Antioxidants may delay the start of macular degeneration. This is an eye disease. It’s a leading cause of blindness in people over age 65. The macula is the part of the retina that allows sharp vision. Vitamin C, vitamin E, and carotenoids may help the most.

Unsubstantiated claims

There may be benefits that have not yet been proven through research.

Experts agree that antioxidants from fruits and vegetables reduce the risk for many diseases. They also affect the start of some age-related diseases. But they don't know if antioxidants from supplements have the same effect. Research on this topic has had mixed results.


Antioxidants come in many forms and dosages and are found in whole food diets rich in fruits and vegetables. Read labels and ask your healthcare provider for guidelines.

Women who are pregnant or breastfeeding should talk to their healthcare provider before taking any supplements.

Side effects, toxicity, and interactions

The side effects of antioxidants vary based on the type of antioxidant.

There are no major food or medicine interactions linked with antioxidants.

Online Medical Reviewer: Bianca Garilli MD
Online Medical Reviewer: Chris Southard RN
Online Medical Reviewer: Stacey Wojcik MBA BSN RN
Date Last Reviewed: 5/1/2023