Do Multivitamins Really Work? Science vs Marketing

Multivitamins promise a simple fix. One pill, many nutrients, better health. The real world is more nuanced. Research shows clear benefits for some people and limited or no benefit for most healthy adults. Let’s look at what large trials and guideline bodies actually say, when a multivitamin makes sense, and when your money is better spent on food and lifestyle.

What do the best guidelines say?

In 2022, the U.S. Preventive Services Task Force reviewed dozens of trials and concluded there is insufficient evidence that routine multivitamin use prevents cancer or cardiovascular disease in community-dwelling adults. It specifically recommends against beta-carotene and vitamin E supplements for prevention because beta-carotene increased harm and vitamin E showed no benefit. USPSTFPubMed

Do multivitamins help you live longer?

Across randomized and prospective studies, multivitamin–multimineral use does not reduce all-cause mortality. A systematic review found no mortality benefit overall. American Journal of Clinical NutritionNCBI

What about cancer and heart disease?

• Cancer: In the Physicians’ Health Study II, more than 14,000 male physicians taking a daily multivitamin had a modest reduction in total cancer incidence compared with placebo. The effect size was small, limited to older men, and did not extend to cancer mortality. Results have not been consistently reproduced across all populations.
• Cardiovascular disease: Large primary prevention trials and pooled analyses show little to no benefit of vitamin or multivitamin supplements for preventing major cardiovascular events.

Are there proven harms?

Yes, in specific contexts. Two landmark trials in smokers showed higher lung cancer incidence and mortality with beta-carotene, alone or combined with vitamin A. For smokers and those with asbestos exposure, high-dose beta-carotene is unsafe.

Cognitive health is a possible bright spot

Emerging evidence from the COSMOS program suggests a daily multivitamin may modestly slow cognitive aging in older adults over about three years, with improvements in global cognition and memory. The effect is small and needs replication in diverse groups, but it is one of the few consistent signals in favor of multivitamins.

How much of your “waterfall of nutrients” should come from food?

Most adults can reach needs through diet that includes fruits, vegetables, legumes, whole grains, dairy or fortified alternatives, nuts, seeds, eggs, and varied protein. Authoritative groups emphasize food first because whole foods deliver fiber, phytonutrients, and balanced micronutrient profiles that pills cannot fully replicate. When intake is erratic or restricted, targeted supplementation can help.

Who may benefit from a multivitamin or targeted supplements?

• Pregnancy and preconception: Folic acid is essential to reduce neural tube defects.
• Strict vegans or low-B12 intake: Vitamin B12 is often required.
• Malabsorption or restrictive diets: Bariatric surgery, inflammatory bowel disease, celiac disease, or chronic alcohol use may require tailored supplementation.
• Older adults with low intake: A standard low-dose multivitamin may cover gaps and might support cognition based on COSMOS findings. PubMed
• Documented deficiency: Use the specific vitamin or mineral at an evidence-based dose.

Common marketing claims vs the evidence

Claim: Multivitamins prevent cancer and heart disease.
Evidence: Routine use does not prevent CVD and shows at best a small, population-specific reduction in total cancer in older men. Not generalizable. PubMed

Claim: More antioxidants are always better.
Evidence: High-dose beta-carotene increases lung cancer in smokers. More is not always better. PubMed

Claim: A pill replaces a balanced diet.
Evidence: No supplement reproduces the full benefits of whole foods and dietary patterns that lower chronic disease risk.

Pragmatic guidance if you still want to take one

• Choose a standard-dose product that stays near the daily value and avoids mega-doses.
• Avoid beta-carotene if you smoke or have significant past exposure. PubMed+1
• Pair the pill with the foundations that actually move risk: diet quality, physical activity, sleep, and not smoking. For sleep, you can point readers to your post Why Sleep is the Best Medicine. For lifestyle stress tools, link to 7 Proven Ways to Reduce Stress Naturally Every Day. For basics that support energy and focus, link to Healthy Habits for Busy Students.

A quick word on single vitamins that are often hyped

• Vitamin D: The large VITAL trial did not reduce major cardiovascular events or total cancer incidence; some meta-analyses suggest a small reduction in cancer mortality, not incidence. Test and treat deficiency rather than assuming benefit from universal dosing. PubMedNew England Journal of Medicine
• Vitamin E: No prevention benefit for CVD or cancer in healthy adults and not recommended for that purpose. USPSTF

Conclusion

For most healthy adults, a daily multivitamin is optional, not essential. It is unlikely to extend life or prevent heart disease and cancer. There may be a small cognitive benefit in older adults, and there are clear benefits for people with specific needs such as pregnancy, vegan diets lacking B12, or medically diagnosed deficiencies. If you choose to take one, use a standard dose and keep your focus on the fundamentals that drive health outcomes: diet quality, movement, sleep, stress control, and avoiding tobacco.

References and further reading

• U.S. Preventive Services Task Force. Vitamin, mineral, and multivitamin supplementation to prevent cardiovascular disease and cancer. Recommendation statement, 2022. USPSTFAAFP
• O’Connor EA et al. Vitamin and mineral supplements for primary prevention of cardiovascular disease and cancer. Evidence review for USPSTF, 2022. PubMed
• Gaziano JM et al. Physicians’ Health Study II. Daily multivitamin and total cancer in men. JAMA, 2012. PubMed
• Macpherson H et al. Multivitamin–multimineral supplementation and all-cause mortality. Am J Clin Nutr, 2013. American Journal of Clinical Nutrition
• ATBC Study and CARET: elevated lung cancer risk with beta-carotene in smokers. PubMed+1atbcstudy.cancer.govFred Hutch
• Baker LD et al. COSMOS-Mind and related COSMOS analyses on cognition with multivitamins. Am J Clin Nutr and trial site summaries, 2022–2023. PubMedcosmostrial.org
• Manson JAE et al. VITAL trial summaries on vitamin D and omega-3s for primary prevention. PubMedNew England Journal of Medicine
• Harvard Health overview on multivitamins and practical considerations. Harvard Health+1