March 21, 2017


Other name(s):

free radical scavengers

General description

Antioxidants help prevent free radicals from damaging the body. It does this by neutralizing them.

A free radical is an atom or molecule that contains one or more unpaired electrons. These unpaired electrons want to bond to atoms or molecules. So, they do easily. This bonding 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 (SOD)


  • 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, cancer prevention, 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 supplements 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 man-made (synthetic) antioxidant supplements has the same effect on the body as eating foods rich in these substances. The Women's Antioxidant Cardiovascular Study (studying women 45 years and older) looked at vitamin C, vitamin E, and beta-carotene. It found that these substances didn’t prevent heart disease or stroke in women under 65 years. But it did decrease the risk in women 65 and older. 

Antioxidants, especially vitamin C, vitamin E, and carotenoids, may delay the onset of macular degeneration. Macular degeneration is an eye disease. It’s a leading cause of blindness in people over age 65. The macula is the part of the retina responsible for sharp and acute vision.

Antioxidants interfere with these disease processes by stopping free radicals.

Unsubstantiated claims

Please note that this section reports on claims that have not yet been substantiated through scientific studies.

Experts agree that antioxidants from fruits and vegetables reduce the risk for many diseases. They also affect the onset of age-related illnesses. However, it isn’t known if antioxidants from supplements has the same effect. Research on this topic has had mixed results.


Antioxidants come in many forms and dosages. Check the package label 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 individual antioxidant.

There are no significant food or drug interactions linked with antioxidants.




March 21, 2017

Reviewed By:  

Poulson, Brittany, RD,Wilkins, Joanna, R.D., C.D.