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Multivitamins and Multiminerals: Who Might Consider Them and What the Evidence Shows

What multivitamins and multiminerals are, what large trials found, how label amounts compare with official upper levels, and when to ask a clinician or pharmacist first.

Content last updated . This page has not been medically reviewed.

If a child has swallowed vitamins

MedlinePlus says a severe iron overdose can happen if a child eats adult multivitamins, such as prenatal vitamins. [1] In the US, call Poison Help at 1-800-222-1222, or 911 if the child is unwell. [1] Do not wait for symptoms: MedlinePlus notes that symptoms may go away for a few hours and then return a day or later. [1] For other countries see poison help by country, and read iron overdose and child safety.

Overview

A multivitamin or multimineral is one product that combines many vitamins and minerals. NCCIH, a US government research center, describes one survey definition as a product having 10 or more of them. [2] The NHS (UK) says most people should get all the nutrients they need from a varied and balanced diet, although some people may need extra supplements. [3]

This page is the home for the multivitamin pages on this site: what is in a multivitamin, large trial results, with or without iron, side effects and B-complex and calcium-plus-vitamin-D products. It gives information, not a routine that suits everyone.

What the research shows

QuestionWhat the source foundLabel
Preventing heart disease or cancer in healthy adultsThe US Preventive Services Task Force (USPSTF, 2022) said the evidence is insufficient to judge the balance of benefits and harms of multivitamins for this purpose. [4]Insufficient evidence
Cancer, in a review for the USPSTFFour trials (48,859 people) linked multivitamin use to slightly lower odds of any cancer (odds ratio 0.93), but the authors listed important limitations. [5]Mixed
Total cancer in older menPhysicians' Health Study II: 14,641 US male physicians aged 50 or older, median follow-up 11.2 years. Total cancer was modestly lower (hazard ratio 0.92, 95% CI 0.86 to 0.998). [6]Promising but limited (one product, men only)
Heart attacks and strokes in the same menNo significant effect on major cardiovascular events (hazard ratio 1.01). [7]No good evidence of benefit
Thinking and memoryNo benefit in 5,947 male physicians aged 65 or older. [8] A small benefit on a global thinking score in COSMOS-Mind (2,262 people, mean age 73, 3 years). [9]Mixed
Death from any causeA 2013 pooled analysis of 21 articles (91,074 people) found no effect on all-cause mortality. [10]No good evidence of benefit

Each trial tested one product in one group, mostly older and well-nourished US adults. Results do not transfer to other products, other ages or people with a diagnosed deficiency. A small average effect in a group is not a promise for one person. NCCIH sums up that most research shows multivitamins do not lead to living longer, slowing cognitive decline, or lowering the chance of cancer, heart disease or diabetes. [2] Details are on the large trials page.

Who might ask a clinician about one

The NHS expects most people to get what they need from food. [3] Situations where a conversation with a clinician is reasonable include pregnancy or planning pregnancy (the NHS recommends a folic acid supplement from before pregnancy until 12 weeks), [11] a vegan diet (the NHS says vegans may not get enough vitamin B12), [11] and medicines such as proton pump inhibitors, which the NHS says can affect how much B12 and folate the body absorbs. [12] Tiredness alone cannot tell you which nutrient is low; the NHS says deficiency is usually diagnosed from symptoms and a blood test. [12] See vitamin deficiency testing.

Amounts that add up

A multivitamin is rarely your only source: fortified cereal and other supplements count too. Official upper figures differ by body, year and population, and neither is universal. US figures from NIH Office of Dietary Supplements could not be verified (the site blocked our download), so none are quoted.
NutrientNHS (UK, 2020): supplement amountsEFSA (EU, 2025 overview): upper level, adults
Vitamin AFood plus supplements at 1.5 mg (1,500 µg) a day or less; many multivitamins contain it [13]3,000 µg retinol equivalents a day, preformed vitamin A only [14]
Vitamin B6Do not take more than 10 mg a day in supplements unless a doctor advises [11]12 mg a day [14]
Folic acid1 mg or less a day is unlikely to cause harm; more can mask B12 deficiency [11]1,000 µg a day, supplemental forms only [14]
Iron17 mg or less a day of supplements is unlikely to cause harm [15]No upper level set; a "safe level" of 40 mg a day [14]
ZincNot more than 25 mg a day unless a doctor advises [16]25 mg a day [14]

US labels show Daily Values: 5% DV or less per serving is low and 20% or more is high. [17] Daily Values are label reference amounts, not personal advice. See amounts and duplicate ingredients.

Product quality

Supplements you buy may differ in important ways from products tested in studies. [2] The FDA is not authorized to approve dietary supplements for safety and effectiveness before they are marketed. [22] For what testing marks can and cannot show, see quality testing and certifications.

Related

Multivitamins marketed to women or men · Food-first nutrition · Supplements for healthy aging

Frequently asked questions

Do multivitamins work?

It depends on the goal. For a diagnosed shortage, the missing nutrient is the treatment and a clinician decides. For preventing heart disease or cancer in healthy adults, the USPSTF found the evidence insufficient. [4] Results for thinking tests are mixed. [8][9]

What is the best multivitamin?

This site does not rank or name products. The sources we read suggest checking that nothing is a megadose and that the product does not duplicate other supplements you take. [19] A pharmacist can help compare labels.

Do multivitamins have side effects?

NCCIH says a multivitamin is unlikely to pose any health risks. [2] Problems are tied to high amounts of single nutrients, such as vitamin A or B6, or to iron, which can cause constipation and nausea above 20 mg and can be fatal to young children. [13][11][15]

Do I need a multivitamin?

Not automatically. The NHS says most people should get what they need from a varied diet. [3] If you are unsure, ask a clinician or dietitian rather than guessing from symptoms.

Can I take a multivitamin with my medicines?

Often yes, but not always. Vitamin K affects warfarin, for example. [19] Ask your pharmacist before adding one.

More details: evidence, limits and cautions

The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.

How to read the evidence labels

Labels used on this page: established nutritional role / deficiency treatment, evidence in adequately nourished people, promising but limited, mixed, insufficient evidence, no good evidence of benefit.

Safety, medicines and life stages
NCCIH says taking a multivitamin is unlikely to pose any health risks, but supplements may interact with medicines or pose risks with certain medical problems or before surgery. [2] MedlinePlus warns that high doses of certain vitamins can be toxic and that fat-soluble vitamins (A, D, E and K) can build up in the body. [18] For example, vitamin K can reduce the ability of the blood thinner warfarin to prevent clotting. [19]
  • Pregnancy: the NHS (2015) advises choosing a multivitamin made for pregnancy or one without vitamin A, because high vitamin A can harm the baby. [20]
  • Children: the UK recommends vitamins A, C and D for ages 6 months to 5 years, and the NHS warns that too much of some vitamins can be harmful. [21]
  • Kidney and liver: the NHS says long-term high copper can damage the liver and kidneys, and long-term high nicotinic acid can cause liver damage. [16][11] Ask a clinician before supplements if you have either condition.
  • Surgery: NCCIH says some supplements may raise bleeding risk or affect anesthesia; tell your care team about everything you take well before an operation. [2]

Always check medication interactions, and ask a pharmacist or clinician about your situation.

References
  1. MedlinePlus: Iron overdose (reviewed 14 October 2025). Read 2026-10-23.
  2. NCCIH: Using Dietary Supplements Wisely. Read 2026-10-23.
  3. NHS: Vitamins and minerals. Read 2026-10-23.
  4. USPSTF recommendation statement, Vitamin, Mineral, and Multivitamin Supplementation to Prevent Cardiovascular Disease and Cancer (JAMA 2022). Read 2026-10-23.
  5. Evidence report for the USPSTF: Vitamin and Mineral Supplements for the Primary Prevention of Cardiovascular Disease and Cancer (JAMA 2022). Read 2026-10-23.
  6. Gaziano et al., Multivitamins in the prevention of cancer in men: the Physicians' Health Study II randomized controlled trial (JAMA 2012). Read 2026-10-23.
  7. Sesso et al., Multivitamins in the prevention of cardiovascular disease in men: the Physicians' Health Study II randomized controlled trial (JAMA 2012). Read 2026-10-23.
  8. Grodstein et al., Long-term multivitamin supplementation and cognitive function in men: a randomized trial (Ann Intern Med 2013). Read 2026-10-23.
  9. COSMOS-Mind: Effects of cocoa extract and a multivitamin on cognitive function, randomized clinical trial (Alzheimer's & Dementia 2023). Read 2026-10-23.
  10. Macpherson et al., Multivitamin-multimineral supplementation and mortality: a meta-analysis of randomized controlled trials (Am J Clin Nutr 2013). Read 2026-10-23.
  11. NHS: B vitamins and folic acid. Read 2026-10-23.
  12. NHS: Vitamin B12 or folate deficiency anaemia. Read 2026-10-23.
  13. NHS: Vitamin A. Read 2026-10-23.
  14. EFSA: Overview on Tolerable Upper Intake Levels as derived by the Scientific Committee on Food (SCF) and the EFSA NDA Panel, version 11 (August 2025). Read 2026-10-23.
  15. NHS: Iron. Read 2026-10-23.
  16. NHS: Other vitamins and minerals (beta-carotene, copper, magnesium, potassium, selenium, zinc and others). Read 2026-10-23.
  17. FDA: Daily Value on the Nutrition and Supplement Facts Labels (content current as of 3 March 2024). Read 2026-10-23.
  18. MedlinePlus: Vitamins (encyclopedia article, reviewed 21 January 2025). Read 2026-10-23.
  19. NIA: Vitamins and Minerals for Older Adults (content reviewed 2 January 2021). Read 2026-10-23.
  20. NHS: Vegetarian and vegan diets during pregnancy (information reviewed April 2015). Read 2026-10-23.
  21. NHS: Vitamins for children. Read 2026-10-23.
  22. FDA: Information for Consumers on Using Dietary Supplements. Read 2026-10-23.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.