Do multivitamins actually work?

What do the big trials show?

The NIH Office of Dietary Supplements summarises the research plainly: multivitamin and mineral products do not reliably reduce chronic disease risk or mortality.

The main COSMOS trial followed about 21 000 adults for a median of 3.6 years and found no reduction in total invasive cancer or cardiovascular events.

Who is most likely to benefit?

• People on restricted or low-energy diets, including some weight-loss diets, where whole food cannot supply every micronutrient.
• Vegans, mainly for vitamin B12 (how much B12 vegans need).
• Pregnancy and planning pregnancy, using a prenatal formula with folic acid, not a standard multivitamin.
• Older adults, where B12 absorption from food declines and the COSMOS memory signal is of interest.
• People with conditions that impair absorption, under medical supervision.

Do multivitamins help athletes?

Not for performance in well-fed athletes. The AIS classes multivitamins in Group B, meaning emerging evidence and use under a protocol. A multivitamin is also a weak tool for a real deficiency: a typical product carries 200 to 400 IU of vitamin D and 1 to 10 mg of iron, so a runner with low ferritin needs testing and targeted treatment, not a multi (see iron for runners). If you are drug-tested, remember that SAIDS applies strict liability to everything you swallow, and no multivitamin sold in South Africa is endorsed by SAIDS.

Are there downsides?

At about 100% of daily needs, risk is low. The concerns are megadoses and stacking:

• Smokers should avoid products with large amounts of beta-carotene or vitamin A, which were linked to more lung cancer in trials.
• Excess preformed vitamin A in pregnancy can increase the risk of birth defects.
• Warfarin users should speak to their doctor before taking anything containing vitamin K.
• Iron-containing products must be stored away from young children.

What does this mean in rand?

As of October 2026, a South African multivitamin costs roughly R3 to R18 a day (Dis-Chem Living Fit and Faithful to Nature). If your diet is varied and you eat protein, vegetables, fruit and dairy or fortified alternatives, the same money is usually better spent on food. If you do choose one, compare label doses in our multivitamin guide, see the ranking on our best multivitamin page and read which vitamins athletes actually need. A multivitamin cannot compensate for a poor diet, and it does not give you energy.

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