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Do Antioxidant Supplements Work? An Honest Overview of the Evidence

An honest overview of what Cochrane reviews, the NIH and large trials found on antioxidant supplements for death, cancer, heart disease, eyes and memory, and where harm was seen.

Content last updated . This page has not been medically reviewed.

Quick answer
For most people and most diseases studied, antioxidant supplements have not been shown to help, and in a few cases they have been linked to harm. The NIH National Center for Complementary and Integrative Health (NCCIH) puts it this way: except for age-related macular degeneration (AMD), there is currently no evidence that antioxidant supplements have a positive impact on cancer, cardiovascular disease, cataracts or Alzheimer's disease. [1] Foods are a different story: NCCIH describes extensive evidence that people who eat more vegetables and fruits have lower risks of chronic disease. [1]

What the main reviews and trials found

QuestionWhat the source foundLabel
Do supplements lower the risk of dying?A Cochrane review pooled 78 randomized trials (296,707 people) of beta carotene, vitamin A, vitamin C, vitamin E and selenium. Overall there was no significant effect in one model; in 56 low-risk-of-bias trials, mortality was higher (relative risk 1.04). Beta carotene and vitamin E seemed to increase mortality; vitamin C and selenium did not significantly change it. The authors found no evidence to support antioxidant supplements for primary or secondary prevention. [2]No good evidence of benefit; evidence of harm for some
Cancer preventionThe National Cancer Institute (NCI) summarized nine randomized trials and found no evidence that antioxidant supplements are beneficial for preventing cancer. [3] In ATBC (male smokers) beta carotene was linked to higher lung cancer incidence. [4] In CARET (smokers, former smokers and asbestos-exposed workers) beta carotene plus retinol raised lung cancer risk and the trial stopped early. [5] In SELECT, vitamin E was linked to more prostate cancer in healthy men. [6]No good evidence of benefit; evidence of harm in these groups
Heart diseaseNCCIH says current evidence does not support antioxidant supplements for preventing cardiovascular disease. The 2022 US Preventive Services Task Force recommended against beta carotene or vitamin E for this purpose. [1]No good evidence of benefit
CataractA Cochrane review of 9 trials (117,272 people) found no evidence that beta carotene, vitamin C or vitamin E prevent or slow age-related cataract. [7]No good evidence of benefit
AMD progressionCochrane (2023) found moderate-certainty evidence that the antioxidant-plus-zinc formula from the AREDS trial probably slows progression to late AMD in people who already have AMD. [8] The National Eye Institute (NEI) says these supplements do not prevent AMD onset. [9]Promising; applies to a specific group and formula
Memory and thinkingNCCIH describes two 2018 reviews with mixed results; effects were small and evidence low certainty. [1]Mixed

Frequently asked questions

Do antioxidant supplements help you live longer?

In the Cochrane review of 78 trials the authors found no evidence to support antioxidant supplements for prevention, and beta carotene and vitamin E seemed to increase mortality. [2]

Are they useful for eye health?

Only for one situation in the evidence we read: people who already have AMD, using a specific formula tested in the AREDS trials. They did not prevent AMD or cataract. [9][7]

Are antioxidant-rich foods better than supplements?

Different questions. NCCIH reports lower chronic disease risk with higher vegetable and fruit intake, but not from purified supplements. [1] See Antioxidant Foods vs Antioxidant Supplements.

Who is most at risk from high-dose antioxidants?

NCCIH singles out smokers and people with occupational asbestos exposure for beta carotene, and people on blood thinners for vitamin E. [1]

Is there any antioxidant supplement that is proven safe at any amount?

Proper evidence not found in the sources we read. NCCIH says antioxidant supplements are not necessarily safe. [1]

More details: evidence, limits and cautions

The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.

How to read the evidence labels

Labels used on this page: evidence in adequately nourished people, promising but limited, mixed, no good evidence of benefit, evidence of harm. This page covers antioxidant vitamins and minerals tested in trials. Other compounds (coenzyme Q10, lipoic acid, curcumin and others) have their own pages and should not be assumed to behave the same way. See Antioxidants Explained and the hub, Antioxidants.

Why trials and food studies disagree
NCCIH gives reasons supplements may not match foods. Benefits of a high-vegetable diet may come from other substances or from other lifestyle habits. Purified antioxidants may act differently than those in foods. High doses in supplements may have different effects than the smaller amounts in foods. [1] The NCI says how the antioxidants and other substances in food interact is an active area of ongoing research. [3] The Nature Reviews Drug Discovery 2021 review notes that antioxidants successful in preclinical studies have given disappointing clinical results. [10] For more see The Antioxidant Paradox.
Limits and uncertainty
  • Most large trials tested a few antioxidants (vitamin E, beta carotene, vitamin C, selenium), often at amounts above usual food intake. Cochrane notes that cataract trials used doses higher than the recommended daily allowance. [7] Results do not transfer to other antioxidants or forms.
  • The Cochrane mortality review pooled people who were healthy and people with diseases. Findings depend on the model used, which is why the overall result was not significant in one analysis and was in another. [2]
  • Trials of other compounds (coenzyme Q10, curcumin, resveratrol) are covered on their own pages; we did not pool them here.
Safety and who should ask first
NCCIH says antioxidants can have harmful effects at high doses: beta carotene and lung cancer and heart death risk, mostly in people at high risk such as smokers; high-dose vitamin E and bleeding risk, with possible interactions with anticoagulant or antiplatelet medicines; high-dose vitamin C and diarrhea, nausea and cramps, plus worse iron overload in hemochromatosis. [1] In one study an antioxidant combination reduced the cholesterol-lowering effect of two drugs. [1] People in cancer treatment should ask their care team before any antioxidant. [3]

Talk to a clinician or pharmacist if you are pregnant or nursing, giving a supplement to a child, have kidney or liver conditions, are preparing for surgery or take medicines. [1] See Medication Interactions, Antioxidants and Medicines and Quality Testing and Certifications.

References
  1. NCCIH, Antioxidant Supplements: What You Need To Know (last updated July 2023). Read 2026-10-23.
  2. Bjelakovic et al., Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases (Cochrane Database Syst Rev 2012). Read 2026-10-23.
  3. National Cancer Institute, Antioxidants and Cancer Prevention. Read 2026-10-23.
  4. ATBC Cancer Prevention Study Group, The effect of vitamin E and beta carotene on the incidence of lung cancer and other cancers in male smokers (N Engl J Med 1994). Read 2026-10-23.
  5. Omenn et al., Effects of a combination of beta carotene and vitamin A on lung cancer and cardiovascular disease (CARET, N Engl J Med 1996). Read 2026-10-23.
  6. Klein et al., Vitamin E and the risk of prostate cancer: SELECT (JAMA 2011). Read 2026-10-23.
  7. Mathew et al., Antioxidant vitamin supplementation for preventing and slowing the progression of age-related cataract (Cochrane Database Syst Rev 2012). Read 2026-10-23.
  8. Evans and Lawrenson, Antioxidant vitamin and mineral supplements for slowing the progression of age-related macular degeneration (Cochrane Database Syst Rev 2023). Read 2026-10-23.
  9. National Eye Institute, AREDS/AREDS2 Clinical Trials (updated October 2025). Read 2026-10-23.
  10. Forman and Zhang, Targeting oxidative stress in disease: promise and limitations of antioxidant therapy (Nat Rev Drug Discov 2021). Read 2026-10-23.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.