A daily multivitamin sits on millions of kitchen counters as a small act of self-care. It feels responsible. It’s also one of the most thoroughly studied supplements in modern medicine, and the verdict has been consistent for years: for the average healthy adult eating a reasonably varied diet, daily multivitamins produce no meaningful health benefits.
The big trials have been clear
The Physicians’ Health Study II, which followed nearly 15,000 male physicians for over a decade, found no reduction in cardiovascular events, no reduction in cancer mortality (with a small reduction in total cancer incidence), and no improvement in cognitive decline from daily multivitamin use. The U.S. Preventive Services Task Force, in its 2022 update, recommended against routine vitamin and mineral supplementation for cardiovascular disease and cancer prevention in healthy adults, citing insufficient evidence for benefit and modest risk for some specific supplements. The Iowa Women’s Health Study even found small associations between certain supplements and increased mortality. None of this is consistent with “an insurance policy” — it’s closer to “a pill that does very little.”
The deficiency framing doesn’t apply to most diets
Multivitamins were originally formulated to prevent deficiency diseases like scurvy, beriberi, and pellagra. Those conditions are rare in developed countries because food fortification and varied diets cover the bases. Iodized salt, fortified breads, dairy with added vitamin D, and breakfast cereals fortified with B vitamins do the heavy lifting. The average American diet is overcaloric and underfibered, but it’s rarely deficient in the micronutrients a multivitamin contains. Specific populations — pregnant women, vegans, older adults with reduced absorption, people with certain GI conditions — have legitimate targeted needs. The general adult population mostly doesn’t.
Targeted supplementation makes sense; broad does not
Vitamin D deficiency is genuinely common, particularly in northern latitudes and among people with darker skin or limited sun exposure; supplementation has decent evidence for those with low blood levels. Iron supplementation is appropriate for diagnosed deficiency, common in menstruating women. Folate is critical pre-conception and during early pregnancy. B12 supplementation matters for vegans and older adults with absorption issues. Each of these is a specific intervention for a specific problem, ideally guided by bloodwork. None of them require a one-size-fits-all multivitamin, and several are present in multivitamins at doses too low to address actual deficiency.
Risks are small but not zero
High-dose beta-carotene supplementation increased lung cancer risk in smokers in two major trials. Excess iron in non-deficient adults can damage organs. Excess vitamin A is teratogenic. Most multivitamins keep doses at safe levels, but stacking them with fortified foods and other supplements can push intake into ranges with documented harm. The “more is better” intuition is wrong for fat-soluble vitamins in particular.
Bottom line
If you eat a varied diet and aren’t in a special-needs population, a daily multivitamin is mostly an expensive habit. Get bloodwork periodically, supplement deficiencies your doctor identifies, and put the money you’d spend on the bottle toward fresh produce. The evidence has been pointing this direction for a decade.
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