What do multivitamins actually do for healthy adults?
Around a third of adults in wealthy countries take a daily multivitamin. Large randomised trials and long-term cohort studies have tested whether they prevent disease or extend life in people who are not nutritionally deficient.
4 established, 1 disputed, 1 debunked, 1 unresolved. We do not pick an answer; the evidence places each claim. How we decide
11 citations from 3 independent sources - 8 echo the same voices and count once. Graded B1.
Added 3 Jul 2026 - updated 9 Jul 2026
What the four states mean
- Establishedsupported, uncontested
- Disputedcredible sources disagree
- Debunkedrefuted by the evidence
- Unresolvedno settled answer
Established 4supported, uncontested
In generally healthy, well-nourished adults, daily multivitamin use is not associated with lower all-cause mortality.▰▰▰▱▱ likely2 points
Supports- A 2024 analysis of about 390,000 U.S. adults followed for over 20 years found daily multivitamin users had no lower risk of death than non-users.Multivitamin Use and Mortality Risk in 3 Prospective US Cohorts - JAMA Network Open (PMC) primary
- The USPSTF likewise concluded that multivitamin supplements do not reduce all-cause mortality in healthy adults.Vitamin Supplementation to Prevent CVD and Cancer - USPSTF Recommendation primary
The U.S. Preventive Services Task Force found insufficient evidence that multivitamin supplements prevent cardiovascular disease or cancer in healthy, non-pregnant adults.▰▰▱▱▱ likely1 source
Supports- After reviewing 84 trials, the 2022 USPSTF concluded the evidence was insufficient to recommend multivitamins for preventing cardiovascular disease or cancer.Vitamin Supplementation to Prevent CVD and Cancer - USPSTF Recommendation (2022) primary
The USPSTF recommends against taking beta-carotene supplements to prevent cancer or heart disease, because they can increase lung cancer risk in smokers.▰▰▱▱▱ likely1 source
Supports- Trials found beta-carotene supplements increased lung cancer incidence in smokers, leading the USPSTF to recommend against their use.Vitamin Supplementation to Prevent CVD and Cancer - USPSTF Recommendation (2022) primary
Supplements clearly benefit people with specific deficiencies or needs - for example, folic acid before and during early pregnancy reduces neural tube defects.▰▰▱▱▱ likely1 source
Supports- The USPSTF gives a grade A recommendation that all people planning or capable of pregnancy take daily folic acid to reduce the risk of neural tube defects.Folic Acid Supplementation to Prevent Neural Tube Defects - USPSTF Recommendation primary
Disputed 1credible sources disagree
A daily multivitamin modestly reduces overall cancer risk in healthy adults.▰▰▰▱▱ roughly even chance1 against2 points
Supports- The Physicians' Health Study II randomised trial found an 8 percent reduction in total cancer incidence among older male physicians taking a daily multivitamin.Multivitamins in the Prevention of Cancer in Men: Physicians' Health Study II - JAMA (2012) primary
Against- The larger COSMOS trial found no significant reduction in total invasive cancer, and the USPSTF judged the overall cancer-prevention evidence inadequate.Multivitamins in the prevention of cancer and CVD: COSMOS trial (PMC) primary
Debunked 1refuted by the evidence
Taking a daily multivitamin protects against cardiovascular events such as heart attacks and strokes.Refuted by
Some earlier observational studies suggested multivitamin users had lower heart-disease risk, though such findings are prone to healthy-user bias.
refuted1 against2 pointsThe claim rested on- In the Physicians' Health Study II, daily multivitamins did not reduce major cardiovascular events, heart attack, stroke, or cardiovascular death over about 11 years.Multivitamins in the Prevention of Cardiovascular Disease in Men: Physicians' Health Study II (PMC) primary
Refuted by- Some earlier observational studies suggested multivitamin users had lower heart-disease risk, though such findings are prone to healthy-user bias.Vitamin Supplementation to Prevent CVD and Cancer - USPSTF Recommendation (2022) primary
Unresolved 1no settled answer
Whether daily multivitamins slow cognitive decline in older adults is unresolved.▰▰▰▱▱ roughly even chance1 against2 points
Supports- COSMOS sub-studies reported that a daily multivitamin modestly improved memory and slowed cognitive aging in older adults versus placebo.Multivitamin Supplementation Improves Memory in Older Adults (COSMOS-Web) - Am J Clin Nutr (PMC) primary
Against- These cognition findings are recent, were funded partly by industry, have not been independently replicated, and were not part of the USPSTF review.Vitamin Supplementation to Prevent CVD and Cancer - USPSTF Recommendation (2022) primary
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