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What supplements should you take every day?

Written by the Full Measure editorial team, which sells supplements. Approved for publication by the Full Measure owners. Updated .

Drafted with AI assistance from the sources listed below. How we write these

Quick answer

Which supplements you need depends on your diet, age and sex. Three entries are graded strong: vitamin D and omega-3 for raising blood levels, and iron for women who menstruate. A multivitamin can fill gaps. Adults need 15 to 20 mcg (600 to 800 IU) of vitamin D and 8 to 18 mg of iron a day.1,2

Key facts

  • Vitamin D and omega-3 are graded strong for a blood level, which is a narrower result than a health outcome. In the largest vitamin D trial, a higher blood level did not change the main outcomes.3,4
  • Women aged 19 to 50 need 18 mg of iron a day, against 8 mg for men.2
  • In national survey data, 39% of people aged 4 and older got less calcium than the estimated average requirement, and 48% of Americans got less magnesium.5,6
  • Vitamin B12 occurs naturally only in animal foods, and NIH lists people who eat little or no animal food among those more likely to run low.7,8
  • A multivitamin cannot take the place of a varied diet, because foods also supply fiber and other components that a multivitamin does not.9
  • Upper limits count different sources: the vitamin D limit of 100 mcg includes food, while the magnesium limit of 350 mg counts supplements and medicines only.10,11

A multivitamin for gaps

A multivitamin is the one product that covers many nutrients at once. NIH says people who do not get enough from food, or who avoid certain foods, might consider one. The entry below is about gaps and not about extra.9

Helps fill gaps in vitamin and mineral intake when diet falls short*12

Moderate evidence

The NIH Office of Dietary Supplements states that taking a multivitamin and mineral raises nutrient intakes and helps people reach recommended amounts when food alone does not. In a study of 90,771 adults that it cites, about three quarters of men had adequate intakes from food alone and 84% did once a multivitamin was counted. This product supplies 50% or more of the Daily Value for 18 of its 20 listed nutrients; calcium (4%) and magnesium (12%) are token amounts.

Amount studied: One basic multivitamin and mineral a day, with most nutrients close to recommended amounts

Vitamin D and omega-3

Both carry a strong grade. Read the basis under each one, because the result is a blood level and the entries say what it does not show.

Raises and maintains blood levels of vitamin D*1,3

Strong evidence

In the VITAL trial, 2,000 IU a day raised average blood 25-hydroxyvitamin D from 29.8 to 41.8 ng/mL after one year among the 1,644 participants who had repeat blood tests, while levels on placebo barely changed. NIH notes that vitamin D3 raises blood levels more, and keeps them up longer, than vitamin D2.

Amount studied: 2,000 IU (50 mcg) of vitamin D3 a day

Raises EPA and DHA levels in the blood*4,13

Strong evidence

In a five-month randomized trial in 115 healthy adults, 600 mg a day of EPA plus DHA from standard fish oil raised the omega-3 index (the share of EPA and DHA in red blood cell membranes) by 59%, with no change on placebo. NIH notes that all the common forms of omega-3 supplement raise blood EPA and DHA. Typical US intake from food is only about 90 mg a day.

Amount studied: 300 to 1,800 mg of EPA plus DHA a day; the 59% rise was at 600 mg a day for about five months

Calcium, magnesium, zinc and iron

Calcium, magnesium and zinc are nutrients that many people take in below the estimated average requirement, so their entries are about reaching the recommended amount. Iron is different: its strong entry is limited to women who menstruate.

Helps you reach the recommended daily calcium intake when food falls short*5

Moderate evidence

National survey data from 2007 to 2010 show that 39% of people aged 4 and older get less calcium than the estimated average requirement from food and supplements, including 49% of children aged 4 to 18. Women average 842 mg a day from food alone; counting supplements, their average rises to 1,009 mg, close to the 1,000 to 1,200 mg they need.

Amount studied: Recommended intake: 1,000 to 1,200 mg a day for adults, from food and supplements combined

Helps you reach the recommended daily magnesium intake*6

Moderate evidence

National survey data from 2013 to 2016 show that 48% of Americans take in less magnesium from food and drink than the estimated average requirement. One serving supplies 275 mg, 65% of the Daily Value. In an earlier national survey, adults who used magnesium supplements had average total intakes well above requirement levels.

Amount studied: Recommended intake: 400 to 420 mg a day for men, 310 to 320 mg for women, from all sources

Helps you reach the recommended daily zinc intake when food falls short*14,15,16

Moderate evidence

Most people in the United States get enough zinc from food, but national survey data from 2005 to 2016 show that 15% of adults take in less than the estimated average requirement. Teenage girls (20.9% below it), older adults, people who are pregnant and people who eat no meat are more likely to fall short. NIH says people who follow vegetarian or vegan diets might benefit from zinc supplements.

Amount studied: Recommended intake: 11 mg a day for men and 8 mg for women, from food and supplements

Helps women who menstruate build hemoglobin and iron stores*2,17,18

Strong evidence

A Cochrane review of 67 randomized trials in 8,506 women who menstruate found that daily iron raised hemoglobin (51 trials, 6,861 women, high-quality evidence) and iron stores, and made low iron less common. Women aged 19 to 50 need 18 mg a day, against 8 mg for men, because menstruation adds to their iron losses. Iron also roughly doubled reports of stomach and bowel side effects in these trials.

Amount studied: Daily iron tablets taken at least five days a week; the amount varied between trials

Vitamin B12 and folate

Two of these entries are tied to groups more likely to run low on vitamin B12: people over 50 and people who eat little or no animal food. The folate entry describes a role in making red blood cells.

Supplies vitamin B12 in a free form that most adults over 50 absorb well*7,8

Moderate evidence

Many older adults make too little stomach acid to release the B12 bound to protein in food. B12 in supplements and fortified foods is not bound to protein, so it does not need that step, and NIH advises people over 50 to get most of their B12 from these sources. Depending on the definition, 3% to 43% of older adults living at home have low B12.

Amount studied: Recommended intake: 2.4 mcg a day for adults over 50, mostly from fortified foods or supplements

Supplies vitamin B12 for people who eat little or no animal food*7,8,19

Moderate evidence

B12 occurs naturally only in animal foods, and NIH lists vegans and vegetarians among the groups more likely to run low, adding that fortified foods and B12 supplements help close the gap. In a 90-day trial in 40 vegans and vegetarians with marginal B12 status, 50 mcg a day under the tongue brought blood B12 back to adequate levels and lowered methylmalonic acid, a marker of shortage; 2,000 mcg once a week did too.

Amount studied: Recommended intake: 2.4 mcg a day; the trial used 50 mcg a day or 2,000 mcg once a week

Contributes to normal blood formation*20,21,22

Moderate evidence

Red blood cells are made from rapidly dividing cells, which need folate to copy their DNA. NIH explains that when this step falters, the body makes red blood cells that are unusually large and abnormal, and the folic acid prescribing label describes an outside source of folate as required to keep red blood cell production normal. The EU permits the statement that folate contributes to normal blood formation.

Amount studied: Recommended intake: 400 mcg DFE a day for adults, from all sources

Vitamins A, E and K

These three are fat soluble. Their entries are mostly about reaching the recommended intake and not about more, and each has its own caution below.23,24,25

Helps you reach the recommended daily vitamin A intake*23,26

Moderate evidence

In national survey data from 2017 to 2018, average vitamin A intakes from food and drink were 682 mcg RAE a day for men and 616 mcg RAE for women, below the recommended 900 and 700 mcg RAE, although in 2003 to 2006 data fewer than 1% of Americans had the low blood levels that signal a shortage. In a study of 90,771 adults, vitamins A and E and zinc were the nutrients whose intakes rose most when multivitamins were counted, and 10% to 15% of multivitamin users had excessive intakes of vitamin A, iron and zinc.

Amount studied: Recommended intake: 900 mcg RAE a day for men and 700 mcg RAE for women, from all sources

Helps you reach the recommended daily vitamin E intake*24,27,28

Moderate evidence

National surveys have found that the diets of most Americans provide less vitamin E than the recommended 15 mg a day, although the estimates may be low because fats added in cooking are often not counted, and clear signs of a shortage are very rare in healthy people. In a study of 90,771 adults, vitamins A and E and zinc were the nutrients whose intakes rose most when multivitamins were counted. A typical once-daily multivitamin supplies about 13.5 mg.

Amount studied: Recommended intake: 15 mg a day for adults and 19 mg while breastfeeding, from all sources

Contributes to normal blood clotting*25,29,30

Moderate evidence

A long-established role of the vitamin: NIH describes vitamin K as the helper for an enzyme that makes the proteins blood needs to clot, including prothrombin. Most Americans get enough from food, and for a healthy person eating a varied diet it is almost impossible to take in so little that standard clotting tests change. More is not more: ordinary changes in intake have rarely been shown to change clotting time, and in a trial of 42 healthy adults, MK-7 at up to 360 mcg a day did not change thrombin generation, a lab measure of clotting.

Amount studied: Adequate intake of 90 mcg a day for women and 120 mcg for men, from all sources

How much adults need

Recommended daily amounts for adults, from all sources1,2,5,6,7,13,14,23,24,25,31,32,33
NutrientRecommended per day
Vitamin D15 mcg (600 IU) from 19 to 70, 20 mcg (800 IU) from 71
Calcium1,000 mg, rising to 1,200 mg for women from 51 and men from 71
Magnesium400 to 420 mg for men, 310 to 320 mg for women
Zinc11 mg for men, 8 mg for women
Iron8 mg for men, 18 mg for women from 19 to 50, 8 mg for women from 51
Vitamin B122.4 mcg
Folate400 mcg DFE
Vitamin A900 mcg RAE for men, 700 mcg RAE for women
Vitamin E15 mg
Vitamin K120 mcg for men, 90 mcg for women (adequate intake)
Omega-3 (EPA plus DHA)No US target is set. The European Food Safety Authority uses 250 mg as a reference amount

A label shows each nutrient as a percentage of its Daily Value. That figure is often, but not always, close to the recommended amount, so compare grams and milligrams as well as percentages.9,12

Food first

A multi cannot take the place of a varied diet: foods also supply fiber and other components that a multi does not. Federal dietary guidelines say most nutrients should come from food and drinks.9

Ordinary fruit, vegetables, grains, nuts, seeds and beans have essentially no vitamin D. NIH lists apples, bananas, broccoli, carrots, almonds, brown rice, whole wheat bread and lentils at zero.1

Fortified foods provide most of the vitamin D in American diets. Almost all US milk is fortified with about 3 mcg (120 IU) a cup, and many plant milks, breakfast cereals and some brands of orange juice, yogurt and margarine have vitamin D added. Cheese and ice cream are usually not fortified.1,10

Cold-water fatty fish such as salmon, mackerel, tuna, herring and sardines are rich in EPA and DHA. Leaner fish such as bass, tilapia and cod, and shellfish, have less.13,33

Milk, yogurt and cheese are the main sources of calcium in the US: dairy products and foods made with them supply about 72% of the calcium Americans eat.5,31

Legumes, nuts, seeds, whole grains and green leafy vegetables such as spinach provide magnesium, as do fortified breakfast cereals, milk and yogurt.11

Plant foods have no vitamin B12 unless it is added. Many breakfast cereals and nutritional yeasts are fortified with it, and the B12 they contain is well absorbed.7,8

Upper limits and who should ask first

Adult upper limits per day5,8,10,11,14,18,20,23,24,25,31,33,34
NutrientUpper limitWhat it counts
Vitamin D100 mcg (4,000 IU)All sources
Calcium2,500 mg for ages 19 to 50, 2,000 mg from 51Food and supplements together
Magnesium350 mgSupplements and medicines only
Zinc40 mgAll sources
Iron45 mgFood and supplements
Vitamin A3,000 mcg of preformed vitamin AFood, drinks and supplements
Vitamin E1,000 mgSupplements. Vitamin E in food does not need to be limited
Folic acid1,000 mcgSupplements and fortified foods. Folate in food has no limit
Vitamin B6100 mg (US limit)Food and supplements together
Vitamin B12, vitamin K, omega-3No upper limit is setNot applicable

Going over an upper limit is more likely when a multi is combined with single vitamin or mineral supplements, or with fortified foods and drinks such as breakfast cereals.9,12

  • You take warfarin or another blood thinner. Vitamin K, vitamin E and omega-3 can interact with these medicines.
  • You take levothyroxine or another thyroid medicine. Calcium, iron and magnesium can interact with it.
  • You take metformin or a medicine that lowers stomach acid. Vitamin B12 can run low over time.
  • You have kidney disease. Ask before taking magnesium, potassium or any new supplement.
  • You are pregnant, planning a pregnancy or breastfeeding. Iron, iodine, folate and vitamin A needs change, so ask which products suit you.
  • You have had kidney stones. Calcium, vitamin C and vitamin D each need a check.

Questions people ask

Do I need a multivitamin?

NIH says a multivitamin raises nutrient intakes and helps people reach recommended amounts when food alone does not. It cannot take the place of a varied diet.9,12

Should I have a vitamin D blood test first?

The Endocrine Society's 2024 guideline suggests against routine blood testing for healthy adults, and against taking more than the recommended intake for healthy adults aged 19 to 74.1,35

Is fish oil the same as eating fish?

The omega-3 entry above is about blood levels of EPA and DHA. The Dietary Guidelines for Americans advise adults to eat at least 8 ounces of a variety of seafood a week.36

Can I take everything on this page at once?

Add up each nutrient across every product you take, because upper limits count different sources. The vitamin D limit of 100 mcg includes food, and the magnesium limit of 350 mg counts supplements and medicines only. Our upper limit checker adds up the amounts in our own products.10,11

See what we make

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Sources

  1. National Institutes of Health, Office of Dietary Supplements. Vitamin D: Fact Sheet for Health Professionals. Updated June 27, 2025. Opened 2026-10-07.
  2. Office of Dietary Supplements, National Institutes of Health. Iron: Fact Sheet for Consumers. Updated August 17, 2023. Opened 2026-10-07.
  3. Manson JE, et al. Vitamin D Supplements and Prevention of Cancer and Cardiovascular Disease. N Engl J Med. 2019;380(1):33-44. Opened 2026-10-01.
  4. Flock MR, et al. Determinants of erythrocyte omega-3 fatty acid content in response to fish oil supplementation: a dose-response randomized controlled trial. J Am Heart Assoc. 2013;2(6):e000513. Opened 2026-10-01.
  5. Office of Dietary Supplements, National Institutes of Health. Calcium: Fact Sheet for Health Professionals. Updated June 22, 2026. Opened 2026-10-07.
  6. National Institutes of Health, Office of Dietary Supplements. Magnesium: Fact Sheet for Health Professionals. Updated January 6, 2026. Opened 2026-10-06.
  7. National Institutes of Health, Office of Dietary Supplements. Vitamin B12: Fact Sheet for Consumers. Updated December 15, 2023. Opened 2026-10-07.
  8. National Institutes of Health, Office of Dietary Supplements. Vitamin B12: Fact Sheet for Health Professionals. Updated July 2, 2025. Opened 2026-10-07.
  9. National Institutes of Health, Office of Dietary Supplements. Multivitamin/mineral Supplements: Fact Sheet for Consumers. Updated February 15, 2024. Opened 2026-10-07.
  10. Office of Dietary Supplements, National Institutes of Health. Vitamin D: Fact Sheet for Consumers. Updated November 8, 2022. Opened 2026-10-07.
  11. Office of Dietary Supplements, National Institutes of Health. Magnesium: Fact Sheet for Consumers. Updated March 22, 2021. Opened 2026-10-06.
  12. National Institutes of Health, Office of Dietary Supplements. Multivitamin/mineral Supplements: Fact Sheet for Health Professionals. Updated July 17, 2024. Opened 2026-10-01.
  13. National Institutes of Health, Office of Dietary Supplements. Omega-3 Fatty Acids: Fact Sheet for Health Professionals. Updated August 22, 2025. Opened 2026-10-07.
  14. National Institutes of Health, Office of Dietary Supplements. Zinc: Fact Sheet for Health Professionals. Updated January 6, 2026. Opened 2026-10-07.
  15. Office of Dietary Supplements, National Institutes of Health. Zinc: Fact Sheet for Consumers. Updated October 4, 2022. Opened 2026-10-07.
  16. National Institutes of Health, Office of Dietary Supplements. Dietary Supplements for Immune Function and Infectious Diseases: Fact Sheet for Health Professionals. Updated March 10, 2025. Opened 2026-10-07.
  17. Low MS, Speedy J, Styles CE, De-Regil LM, Pasricha SR. Daily iron supplementation for improving anaemia, iron status and health in menstruating women. Cochrane Database Syst Rev. 2016;4:CD009747. Opened 2026-10-07.
  18. Office of Dietary Supplements, National Institutes of Health. Iron: Fact Sheet for Health Professionals. Updated September 4, 2025. Opened 2026-10-07.
  19. Del Bo' C, Riso P, Gardana C, et al. Effect of two different sublingual dosages of vitamin B12 on cobalamin nutritional status in vegans and vegetarians with a marginal deficiency: a randomized controlled trial. Clin Nutr. 2019;38(2):575-583. Opened 2026-10-07.
  20. National Institutes of Health, Office of Dietary Supplements. Folate: Fact Sheet for Health Professionals. Updated November 30, 2022. Opened 2026-10-07.
  21. Folic acid tablets, 1 mg: prescribing information (Rising Pharma Holdings). DailyMed, U.S. National Library of Medicine. Published August 3, 2026. Opened 2026-10-07.
  22. European Commission. Commission Regulation (EU) No 432/2012 of 16 May 2012 establishing a list of permitted health claims made on foods. Official Journal of the European Union, L 136, 25.5.2012, p. 1. Opened 2026-10-07.
  23. National Institutes of Health, Office of Dietary Supplements. Vitamin A and Carotenoids: Fact Sheet for Health Professionals. Updated March 10, 2025. Opened 2026-10-07.
  24. National Institutes of Health, Office of Dietary Supplements. Vitamin E: Fact Sheet for Health Professionals. Updated March 26, 2021. Opened 2026-10-07.
  25. National Institutes of Health, Office of Dietary Supplements. Vitamin K: Fact Sheet for Health Professionals. Updated March 29, 2021. Opened 2026-10-07.
  26. National Institutes of Health, Office of Dietary Supplements. Multivitamin/mineral Supplements: Fact Sheet for Health Professionals. Updated July 17, 2024. Opened 2026-10-07.
  27. National Institutes of Health, Office of Dietary Supplements. Vitamin E: Fact Sheet for Consumers. Updated March 22, 2021. Opened 2026-10-07.
  28. National Institutes of Health, Office of Dietary Supplements. Multivitamin/mineral Supplements: Fact Sheet for Health Professionals. Updated July 17, 2024. Opened 2026-10-07.
  29. Office of Dietary Supplements, National Institutes of Health. Vitamin K: Fact Sheet for Consumers. Updated March 22, 2021. Opened 2026-10-07.
  30. Theuwissen E, et al. Low-dose menaquinone-7 supplementation improved extra-hepatic vitamin K status, but had no effect on thrombin generation in healthy subjects. Br J Nutr. 2012;108(9):1652-1657. Opened 2026-10-07.
  31. Office of Dietary Supplements, National Institutes of Health. Calcium: Fact Sheet for Consumers. Updated September 14, 2023. Opened 2026-10-07.
  32. National Institutes of Health, Office of Dietary Supplements. Folate: Fact Sheet for Consumers. Updated November 1, 2022. Opened 2026-10-07.
  33. Office of Dietary Supplements, National Institutes of Health. Omega-3 Fatty Acids: Fact Sheet for Consumers. Updated July 18, 2022. Opened 2026-10-07.
  34. National Institutes of Health, Office of Dietary Supplements. Vitamin B6: Fact Sheet for Health Professionals. Updated June 16, 2023. Opened 2026-10-07.
  35. Demay MB, et al. Vitamin D for the Prevention of Disease: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2024;109(8):1907-1947. Opened 2026-10-01.
  36. National Center for Complementary and Integrative Health, National Institutes of Health. Omega-3 Supplements: What You Need To Know. Last updated November 2024. Opened 2026-10-07.

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.