Vitamins and Cancer Prevention: Beta-Carotene, E, D, B and Antioxidant Trials
What randomized trials and the US Preventive Services Task Force found about beta-carotene, vitamins E, C, D, B and multivitamins for cancer prevention, including trials that found harm.
Content last updated . This page has not been medically reviewed.
If you have been diagnosed with cancer or are having treatment, talk to your cancer care team before taking any vitamin, antioxidant or multivitamin. The National Cancer Institute (NCI) advises that cancer patients should inform their doctors about their use of any dietary supplement. [1] This page is about preventing cancer in people who do not have it, and it is information only. A clinician or pharmacist can advise on your own situation.
Beta-carotene (and vitamin A) in smokers
| Trial | What was tested | What was found |
|---|---|---|
| ATBC, Finland | 29,133 male smokers aged 50 to 69 took alpha-tocopherol (50 mg a day), beta carotene (20 mg a day), both, or placebo for five to eight years. [3] | Unexpectedly, more lung cancer among men who received beta carotene. [3] |
| CARET, US | 18,314 smokers, former smokers and asbestos-exposed workers took 30 mg beta carotene plus 25,000 IU retinol (as retinyl palmitate) a day. [4] | Relative risk of lung cancer 1.28 in the active group; the trial was stopped early. [4] |
The USPSTF evidence review pooled four trials and found beta carotene (with or without vitamin A) was linked to a higher risk of lung cancer (OR 1.20). [5] Label: evidence of harm in people at high risk of lung cancer. These trials tested supplements, not carotenoids eaten in food.
Vitamin E, selenium and prostate cancer
In SELECT (35,533 men), vitamin E (400 IU a day of all rac-alpha-tocopheryl acetate) did not prevent prostate cancer in the first report. [6] After longer follow-up, 620 men in the vitamin E group developed prostate cancer compared with 529 on placebo, and the authors concluded that vitamin E significantly increased risk among healthy men. [7] In the Physicians' Health Study II, 400 IU of vitamin E every other day and 500 mg of vitamin C daily did not reduce prostate or total cancer. [8] Label: evidence of harm for vitamin E in SELECT; no good evidence of benefit for vitamins E and C. See vitamin E trials.Multivitamins
Among 14,641 male US physicians followed for a median of 11.2 years, a daily multivitamin gave a modest, statistically significant reduction in total cancer (hazard ratio 0.92), with no significant effect on prostate or colorectal cancer. [9] The USPSTF pooled four trials and found a small lower incidence of any cancer (OR 0.93) but said the evidence had important limitations. [5] Label: promising but limited, men only, and not confirmed for women or younger people. See multivitamins.Vitamin D
In VITAL, 25,871 adults taking vitamin D3 (cholecalciferol) 2000 IU a day or placebo for a median of 5.3 years did not have a lower incidence of invasive cancer. [10] The USPSTF pooled 19 trials and found no significant link between vitamin D and any cancer incidence (OR 0.98). [5] Label: no good evidence of benefit for cancer prevention. See vitamin D.Folic acid and other B vitamins
A meta-analysis of 13 randomized trials (49,621 people) found folic acid supplementation did not substantially increase or decrease cancer incidence during the first five years of treatment. [11] A separate observational study of 77,118 adults found that long-term use of vitamin B6 and B12 from individual supplements, but not multivitamins, was associated with a 30% to 40% increase in lung cancer risk among men. [12] It found no such link among women. [12] Observational findings cannot show cause, so the label is mixed, with a warning signal for high-dose single B6 or B12 in men who smoke. See vitamin B6 and vitamin B12.Frequently asked questions
Can vitamins prevent cancer?
Randomized trials have not shown it. The NCI said nine trials of antioxidant supplements did not provide evidence of benefit for primary cancer prevention. [1]
Does beta-carotene raise lung cancer risk?
In smokers and asbestos-exposed workers, two large trials found more lung cancer with beta carotene. [3] [4] The USPSTF recommends against beta carotene supplements for prevention. [2]
Does vitamin E prevent or cause prostate cancer?
It did not prevent it in SELECT or the Physicians' Health Study II, and SELECT's longer follow-up found a higher risk with vitamin E. [7] [8]
Do multivitamins lower cancer risk?
One trial in male physicians found a modest reduction in total cancer. [9] The USPSTF found the evidence insufficient and noted limitations. [5]
Should I take antioxidant vitamins during cancer treatment?
Ask your cancer care team first. Some trials found worse outcomes with antioxidant supplements during therapy. [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, insufficient evidence, no good evidence of benefit, evidence of harm. Trial results apply to the vitamin form, amount, group and length of follow-up tested.
Limits and uncertainty
- The NCI notes that lack of benefit might reflect purified chemicals acting differently from the same nutrients in food. [1]
- The trials described here enrolled middle-aged and older adults, and several enrolled men only. [3] [9]
- These trials say nothing about treating a diagnosed deficiency, which is a clinician's decision.
Safety and who should ask a clinician
- During cancer treatment: some trials found worse outcomes in people who took antioxidant supplements during cancer therapy, especially smokers. [1] See vitamins during cancer treatment.
- Smokers and former smokers: ask before taking beta-carotene or vitamin A. See antioxidant safety and marketing claims.
- Medicines, surgery and pregnancy: see medication interactions and vitamins before surgery. The USPSTF recommendation covered nonpregnant adults. [2]
References
- National Cancer Institute. Antioxidants and Cancer Prevention. NCI fact sheet; review date not shown on the page text read. Read 2026-10-23.
- Vitamin, Mineral, and Multivitamin Supplementation to Prevent Cardiovascular Disease and Cancer: US Preventive Services Task Force Recommendation Statement. JAMA 2022. PubMed abstract. Read 2026-10-23.
- The effect of vitamin E and beta carotene on the incidence of lung cancer and other cancers in male smokers. The New England journal of medicine 1994. PubMed abstract. Read 2026-10-23.
- Effects of a combination of beta carotene and vitamin A on lung cancer and cardiovascular disease. The New England journal of medicine 1996. PubMed abstract. Read 2026-10-23.
- Vitamin and Mineral Supplements for the Primary Prevention of Cardiovascular Disease and Cancer: Updated Evidence Report and Systematic Review for the US Preventive Services Task Force. JAMA 2022. PubMed abstract. Read 2026-10-23.
- Effect of selenium and vitamin E on risk of prostate cancer and other cancers: the Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA 2009. PubMed abstract. Read 2026-10-23.
- Vitamin E and the risk of prostate cancer: the Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA 2011. PubMed abstract. Read 2026-10-23.
- Vitamins E and C in the prevention of prostate and total cancer in men: the Physicians' Health Study II randomized controlled trial. JAMA 2009. PubMed abstract. Read 2026-10-23.
- Multivitamins in the prevention of cancer in men: the Physicians' Health Study II randomized controlled trial. JAMA 2012. PubMed abstract. Read 2026-10-23.
- Vitamin D Supplements and Prevention of Cancer and Cardiovascular Disease. The New England journal of medicine 2019. PubMed abstract. Read 2026-10-23.
- Effects of folic acid supplementation on overall and site-specific cancer incidence during the randomised trials: meta-analyses of data on 50,000 individuals. Lancet (London, England) 2013. PubMed abstract. Read 2026-10-23.
- Long-Term, Supplemental, One-Carbon Metabolism-Related Vitamin B Use in Relation to Lung Cancer Risk in the Vitamins and Lifestyle (VITAL) Cohort. Journal of clinical oncology : official journal of the American Society of Clinical Oncology 2017. PubMed abstract. Read 2026-10-23.