Multivitamins show minimal benefits for healthy adults, with only small reductions in cancer risk but no meaningful effects on cardiovascular disease or mortality.
Large systematic reviews of 84 studies involving over 700,000 people found multivitamins were associated with only a small reduction in cancer incidence (7% relative risk reduction) but showed no significant benefits for cardiovascular disease, death, or cognitive function in healthy adults. Most individual vitamins showed no benefits, and some like beta-carotene actually increased lung cancer risk in high-risk individuals.