Multivitamin and Multimineral: Benefits, Dosage, and Safety

What multivitamin and multimineral is

A multivitamin/multimineral (MVM) is a dietary supplement that combines multiple vitamins and minerals, and often other ingredients, in one product. According to the NIH Office of Dietary Supplements, MVMs and multivitamins (MVs) have no standard or regulatory definition for which nutrients they must contain or in what amounts, so products vary widely in composition. The Agency for Healthcare Research and Quality has defined an MVM in research as a product containing at least three vitamins and minerals in amounts below the Upper Intake Level and no herbs, hormones, or drugs. ODS groups MVMs as basic (broad spectrum, mostly at or below Daily Values or RDAs/AIs), high potency (some nutrients well above the DV, RDA, AI, or even UL), and specialized/condition-specific products that combine nutrients with botanical or specialty ingredients. About one-third of U.S. adults and one-quarter of children and adolescents take an MVM or MV.

What it does

• Increases total intake of vitamins and minerals and can help people reach recommended amounts when diet alone falls short (ODS)
• Serves as a source of key nutrients for specific life stages, for example folic acid, iron, iodine and vitamin D during pregnancy (Dietary Guidelines for Americans)
• Delivers combined micronutrients as a form of nutritional insurance, though the Food and Nutrition Board does not state whether supplements can fully compensate for dietary inadequacies
• Provides nutrients that support normal physiology through their individual roles, since the effect of an MVM depends on the specific nutrients and amounts it contains

Intake and dosing

Multivitamin and Multimineral is not an essential nutrient, so no Recommended Dietary Allowance or Tolerable Upper Intake Level has been set. Doses in studies vary widely. Because supplement doses are not standardised, discuss an appropriate amount with a clinician or pharmacist.

Deficiency and who is at risk

There is no deficiency of a multivitamin itself, because an MVM is a manufactured combination product and not an essential nutrient. Deficiency applies to the individual vitamins and minerals a person may lack. ODS notes that groups at greatest risk of inadequate intake of one or more nutrients include pregnant and breastfeeding women, adult women, non-Hispanic Black individuals, people of low socioeconomic status, and people who are underweight or overweight, and ironically these higher-risk groups are the least likely to take an MVM.

Who may need more

• Women who could become pregnant or are pregnant, mainly for folic acid (400 to 800 mcg/day) plus iron, iodine, and vitamin D per ACOG, USPSTF, CDC, and the Dietary Guidelines
• Adults age 50 and older, who may need vitamin B12 from fortified foods or supplements due to reduced absorption from food
• Exclusively or partially breastfed infants, who need about 400 IU (10 mcg)/day supplemental vitamin D per the American Academy of Pediatrics
• People with poor nutrient intake, low-calorie diets, or restrictive diets such as strict vegetarians and vegans
• People with medical conditions that impair digestion, absorption, or use of nutrients, when a provider recommends it

Food sources

There is no food source of a multivitamin as a product. The individual nutrients it supplies occur across a varied diet: vitamins and minerals are found in fruits, vegetables, whole grains, legumes, nuts, dairy, eggs, meat, poultry, fish, and fortified foods. ODS emphasizes that nutritional needs should be met primarily through the diet, including fortified foods, and that whole foods provide other beneficial components an MVM cannot replace.

Forms and absorption

MVMs come as tablets, capsules, gummies, powders, and liquids, and are sold in formulations tailored to age, sex, and life stage. ODS notes that senior or 50-plus formulations often contain little or no iron and more calcium, vitamin D, and vitamin B12 than products for younger adults, prenatal products generally provide no vitamin A as retinol, and children's products provide age-appropriate amounts. Basic MVMs often contain only small amounts of calcium, magnesium, and potassium, so labels should be checked. Bioavailability varies by the chemical form of each nutrient and by the specific product, and there is no standard composition across brands.

Safety, excess and interactions

Too much

Taking a basic MVM at about recommended amounts is generally safe. However, combining an MVM with single-nutrient supplements and fortified foods can push intake of some nutrients above the Tolerable Upper Intake Level, increasing the chance of adverse effects. In one large cohort, MVM users had excessive intakes of vitamin A, iron, and zinc (10 to 15 percent) and niacin (48 to 61 percent). Smokers and possibly former smokers should avoid MVMs with large amounts of beta-carotene or vitamin A: in one trial 20 mg/day beta-carotene raised lung cancer incidence 18 percent in male smokers, and in another 30 mg/day beta-carotene plus 25,000 IU/day vitamin A raised lung cancer risk 28 percent. Excess preformed vitamin A (retinol) in pregnancy can increase the risk of birth defects; the UL for vitamin A in pregnancy is 2,800 mcg/day for adolescents and 3,000 mcg/day for women.

Interactions to know

• Warfarin (Coumadin, Jantoven) and similar blood thinners: vitamin K in an MVM can reduce the drug's effectiveness, so people on these anticoagulants should talk with their provider before taking any MVM or supplement containing vitamin K (ODS)
• ODS notes that MVMs providing nutrients in recommended amounts do not ordinarily interact with medications, with the vitamin K and warfarin interaction as the one important exception
• Proton pump inhibitors and other acid-reducing medications can decrease absorption of food-bound vitamin B12, which is relevant when relying on an MVM for B12 (Dietary Guidelines for Americans, cited by ODS)

How status is measured

There is no laboratory test for multivitamin status, because an MVM is a combination product rather than a single measurable nutrient. Nutrient status is assessed for the individual vitamins and minerals a product contains, using markers such as serum ferritin for iron, serum 25-hydroxyvitamin D for vitamin D, and serum vitamin B12, when clinically indicated. Routine screening for micronutrient status in healthy people is not standard.

Regulated by the U.S. Food and Drug Administration as a dietary supplement under DSHEA, not as a drug, so MVMs are not FDA-approved to diagnose, treat, cure, or prevent any disease. There is no FDA standard defining which nutrients an MVM must contain or in what amounts. The FDA sets Daily Values that many basic MVMs use for labeling. Manufacturers are responsible for safety and truthful labeling, and can change product composition at will.

What the evidence supports

We grade the strength of evidence behind each common reason people take multivitamin and multimineral, mirroring how the NIH describes it.