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Antioxidants
Antioxidants

Background

Antioxidants are substances that seem to reduce oxidative stress. Oxidative stress is thought to lead to aging and certain diseases such as cancer.

Common supplement ingredients thought to have antioxidant effects include vitamin E, beta-carotene, vitamin C, selenium, and others.

People use antioxidants for various cancers, heart disease, asthma, cystic fibrosis, and many other conditions, but there is no good evidence to support these uses.
When taken by mouth: Antioxidants are likely safe when used appropriately. But certain antioxidants are possibly unsafe when used in large doses. Antioxidants like beta-carotene and vitamin E can cause serious side effects when used in large doses. See specific ingredients for more detailed safety information.

Special Precautions & Warnings:

Pregnancy: Antioxidants are possibly safe when taken by mouth in appropriate doses during pregnancy. See specific ingredients for more detailed safety information.

Breast-feeding: There isn't enough reliable information to know if antioxidants in general are safe to use when breast-feeding. See specific ingredients for detailed safety information.

Effectiveness

Natural Medicines rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.
Likely effective Effectiveness definitions
Possibly effective Effectiveness definitions
Likely ineffective Effectiveness definitions
Possibly ineffective Effectiveness definitions
  • Bladder cancer. Taking antioxidant supplements by mouth doesn't seem to reduce the risk of bladder cancer.
  • Cancer. Taking antioxidant supplements by mouth doesn't seem to prevent cancer or reduce the risk of death from cancer.
  • Cataracts. Taking antioxidant supplements by mouth doesn't seem reduce the risk of cataracts or of needing cataract surgery.
  • Colon cancer, rectal cancer. Taking antioxidants doesn't seem to reduce the risk of colon or rectal cancer.
  • Heart disease. Taking antioxidant supplements by mouth doesn't seem to reduce the risk of heart attack, stroke, or death in people with heart disease.
  • Nonmelanoma skin cancer. Taking antioxidants supplements by mouth doesn't seem to reduce the risk of nonmelanoma skin cancer.
  • Prostate cancer. Taking antioxidant supplements by mouth doesn't seem to reduce the risk of prostate cancer.
There is interest in using antioxidants for a number of other purposes, but there isn't enough reliable information to say whether it might be helpful.
Insufficient evidence Effectiveness definitions

Dosing & administration

Antioxidant products are typically taken by mouth. Common supplement ingredients thought to have antioxidant effects include vitamin E, beta-carotene, vitamin C, selenium, and others. Speak with a healthcare provider to find out which specific antioxidants and what dose might be best for a specific condition.

Interactions with pharmaceuticals

See specific ingredients for interactions with medicines.

Interactions with herbs & supplements

See specific ingredients for interactions with herbs and supplements.

Interactions with foods

See specific ingredients for interactions with foods.
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This monograph was last reviewed on 20/04/2022 22:46:08 and last updated on 22/07/2020 18:49:09. Monographs are reviewed and/or updated multiple times per month and at least once per year.
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