Multivitamins
A safety net for a restricted diet; they don't prevent disease or replace food
What it is
A mix of vitamins and minerals in one product. There is no standard: the manufacturer decides which nutrients go in and how much, so products vary widely.
Benefits
They help people with a limited diet get enough vitamins and minerals (NIH). Studies suggest they do not reliably reduce the risk of chronic disease (NIH); evidence on preventing heart disease and cancer is insufficient (USPSTF). They improve performance only where there is an existing deficiency (AIS).
Dose
Usually 1 capsule or tablet a day, depending on the composition (AIS). Basic products provide most nutrients in amounts that do not exceed daily values; pick one made for your age and sex (NIH). Some products contain far more than the recommended amounts, sometimes above the tolerable upper level.
When to take it
The sources give no advice on timing.
Who it's for
People who get too few nutrients from food: a low-calorie diet, making weight, strict vegetarian or vegan eating, multiple food allergies, travel for more than 2 weeks with a limited food supply (NIH, AIS). Pregnant women are advised to take a daily prenatal vitamin (NIH).
Who can skip it
People who eat a varied diet: no US government agency or professional body promotes regular use (NIH). A multivitamin does not replace a variety of foods, nor supervised treatment of a diagnosed deficiency such as iron deficiency (AIS).
Safety
A basic product with doses close to recommended intakes should be safe for healthy people. The risk is in the total: with other supplements and fortified foods you can exceed the upper level. Smokers and possibly former smokers should avoid large amounts of beta-carotene and vitamin A, which are linked to a higher risk of lung cancer. Excess vitamin A in pregnancy raises the risk of birth defects. Vitamin K weakens the effect of warfarin (NIH).
This is a summary of public sources, not medical advice. If you have a health condition, are pregnant or take medication, talk to a doctor before taking a supplement.
Sources
- Multivitamin/mineral Supplements — Fact Sheet for Health Professionals . NIH Office of Dietary Supplements, 2024.
- AIS Sports Supplement Framework — Group B . Australian Institute of Sport, 2026.
- Vitamin, Mineral, and Multivitamin Supplementation to Prevent Cardiovascular Disease and Cancer: Preventive Medication . U.S. Preventive Services Task Force, 2022.
Other supplements
A week of training and meals built for you
Workoutify plans workouts around your days, time and equipment — and a menu for your goal and macros.