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Vitamin Intake References Compared: US, UK, EU and Canada

Adult reference intakes and upper levels for vitamins C, D, A, B12 and folate side by side for the US, Canada, UK and EU, with source and year, and why the numbers differ.

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

Quick answer
The US, Canada, UK and EU each publish their own vitamin reference values, and the numbers are not the same. No one set is "the" correct one: each applies to its own population, was set by a different panel, in a different year, using different evidence. This page lays out adult values for five vitamins. It does not tell you what to take; a clinician or pharmacist decides that for you. For what the terms mean see RDA, AI, DV and UL and How vitamin requirements are set.

Daily reference intakes for adults

Values are per day for healthy adults, not pregnant or breastfeeding, unless stated. The type of value matters: an RDA, PRI or RNI is meant to cover nearly all healthy people, while an AI is a softer estimate used when evidence is thinner.
VitaminUS: NIH values via MedlinePlus, 2025Canada: Health Canada DRI tables, 2025UK: government recommendations, 2016EU: EFSA, 2017
Vitamin CRDA 90 mg men, 75 mg women [1]RDA 90 mg men, 75 mg women (ages 19 to 30) [2]40 mg, ages 19 to 64 [3]PRI 110 mg men, 95 mg women [4]
Vitamin DRDA 15 mcg (600 IU) ages 19 to 70; 20 mcg (800 IU) over 70 [5]RDA 15 mcg (600 IU), ages 19 to 30 [2]10 mcg, ages 19+ [3]AI 15 mcg, ages 18+ [4]
Vitamin ARDA 900 mcg men, 700 mcg women [6]RDA 900 and 700 mcg RAE (ages 19 to 30) [2]700 mcg men, 600 mcg women, ages 19 to 64 [3]PRI 750 mcg men, 650 mcg women, as retinol equivalents (RE) [4]
Vitamin B12RDA 2.4 mcg, ages 14+ [7]RDA 2.4 mcg (ages 19 to 30) [2]1.5 mcg, ages 19 to 64 [3]AI 4 mcg [4]
FolateRDA 400 mcg, ages 14+ [8]RDA 400 mcg DFE (ages 19 to 30) [2]200 mcg, ages 19 to 64 [3]PRI 330 mcg DFE [4]

The US and Canadian panels developed the DRIs together. [9] The UK vitamin figures come from a 1991 report, with vitamin D from a 2016 review. [3] EFSA's vitamin D value assumes minimal skin synthesis; with sun exposure it says the dietary requirement is lower or may be zero. [4]

Upper levels and safe-intake advice for adults

These are not the same kind of number. The US, Canada and EU publish Tolerable Upper Intake Levels (ULs); the NHS gives advice on amounts unlikely to cause harm, based on a page last reviewed in 2020.
VitaminUS and CanadaUK (NHS)EU (EFSA, overview Aug. 2025)
Vitamin CUL 2,000 mg [2]; MedlinePlus says more than 2,000 mg a day is not recommended [1]More than 1,000 mg a day can cause stomach pain, diarrhoea, flatulence; under 1,000 mg is unlikely to cause harm [10]No adequate data to derive a UL [11]
Vitamin DUL 100 mcg (4,000 IU) for ages 9+ [5]Do not take more than 100 mcg (4,000 IU) a day [12]UL 100 mcg for adults [11]
Vitamin AUL 3,000 mcg RAE [2]Keep total intake from food and supplements to 1.5 mg (1,500 mcg) a day or less [13]UL 3,000 mcg RE, applies to preformed vitamin A (retinol and retinyl esters) [11]
Vitamin B12Not found in the sources read2 mg a day or less in supplements is unlikely to cause harm [14]No defined adverse effects [11]
FolateMedlinePlus: except for women with a prior neural tube defect pregnancy who are planning pregnancy, avoid more than 1,000 mcg a day of folic acid [8]; Health Canada UL 1,000 mcg [2]1 mg or less a day of folic acid supplements is unlikely to cause harm [14]UL 1,000 mcg for folic acid and certain 5-MTHF forms from supplements and fortified foods, not naturally occurring folate [11]

Vitamin C is the clearest example of a gap: the US and Canada set a UL, the EU did not find enough data to set one, and the NHS gives a lower "unlikely to cause harm" figure. Vitamin A shows another: the UK figure is numerically half of the EU and North American upper levels, although the units differ. We did not find a source explaining why the limits differ.

Why the numbers differ

  • Different panels and years. The EU summary is from 2017. [4] The UK vitamin figures date from 1991 (D from 2016). [3] The US and Canadian values for B vitamins come from a 1998 report. [9]
  • Different evidence used. For vitamin C, EFSA used the balance of losses and body pool. [4] For vitamin D, EFSA used serum 25-hydroxy-vitamin D and bone and muscle outcomes. [4] The panels do not all use the same criterion for every vitamin.
  • Different units. EFSA's vitamin A is in retinol equivalents, where 1 mcg RE is 1 mcg retinol, 6 mcg beta-carotene or 12 mcg of other provitamin A carotenoids. [4] Health Canada lists vitamin A in RAE and folate in DFE, and IU for vitamin D. [2] EFSA converts vitamin D as 1 microgram = 40 IU. [4] Do not compare RE and RAE directly unless a source gives the conversion. See Vitamin units explained.
  • Different types of value. EFSA's B12 and vitamin D values are AIs, not PRIs. [4]

Frequently asked questions

Which country's vitamin values should I follow?

There is no universal answer. Use the values published for the country where you live and the group you belong to, and ask a clinician or pharmacist about your own situation. Health Canada, for example, says its values are for apparently healthy people eating a typical mixed North American diet. [2]

Why is the UK vitamin C figure so much lower than the EU or US one?

The panels set their values at different times, using different methods. The UK figure is 40 mg for adults [3]; EFSA's is 110 mg for men and 95 mg for women, based on balancing losses and a body pool. [4] We did not find a source that compares the reasoning directly, so we cannot say more.

What is the difference between an RDA, a PRI and an RNI?

They are the same idea under different names: the intake that is enough for nearly all healthy people (97 to 98 percent in the US and Canada, at least 97 percent for the UK RNI). [9] [15] The EU calls it a Population Reference Intake. [4]

Are IU and mcg the same?

No. For vitamin D, EFSA gives 1 microgram = 40 IU, and the NHS gives 10 micrograms = 400 IU. [4] [12] Conversions differ by vitamin, so use a source that gives the one you need.

Do these numbers apply if I have a health condition?

Not automatically. They are for healthy people. The UK guide says its values make no allowance for disease. [15] Ask your care team.

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.

Pregnancy and breastfeeding
Pregnancy changes some numbers. The US figure for folate in pregnancy is 600 mcg a day [8], and EFSA's table also shows 600 mcg DFE. [4] The NHS (UK) advises women who are pregnant or could become pregnant to take a 400 microgram folic acid supplement until 12 weeks of pregnancy. [14] Official pregnancy advice is for a clinician to apply to you; see Folic acid and folate before and during pregnancy and Vitamins in pregnancy.
Safety notes
References
  1. MedlinePlus, U.S. National Library of Medicine. Vitamin C (encyclopedia article, review date 1/21/2025). Read 2026-10-23.
  2. Health Canada. Dietary reference intakes tables: reference values for vitamins. Page details dated 2025-11-19. Read through a web-fetch tool that summarizes pages, so quotations are the tool's relay of the table; values for ages 19 to 30 agree with the MedlinePlus figures. Read 2026-10-23.
  3. Public Health England. Government Dietary Recommendations: government recommendations for energy and nutrients for males and females aged 1 to 18 years and 19+ years. Published August 2016. Read 2026-10-23.
  4. European Food Safety Authority. Dietary reference values for nutrients: summary report. EFSA supporting publication 2017:e15121, approved 4 December 2017. Read 2026-10-23.
  5. MedlinePlus, U.S. National Library of Medicine. Vitamin D (encyclopedia article, review date 1/21/2025). Read 2026-10-23.
  6. MedlinePlus, U.S. National Library of Medicine. Vitamin A (encyclopedia article, review date 1/21/2025). Read 2026-10-23.
  7. MedlinePlus, U.S. National Library of Medicine. Vitamin B12 (encyclopedia article, review date 1/21/2025). Read 2026-10-23.
  8. MedlinePlus, U.S. National Library of Medicine. Folic acid in diet (encyclopedia article, review date 2/3/2025). Read 2026-10-23.
  9. Institute of Medicine. Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline, chapter 1 "Introduction to Dietary Reference Intakes". National Academies Press, 1998. Read 2026-10-23.
  10. NHS (UK). Vitamin C. Page last reviewed 3 August 2020 (version read). Read 2026-10-23.
  11. European Food Safety Authority. 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.
  12. NHS (UK). Vitamin D. Page last reviewed 3 August 2020 (version read). Read 2026-10-23.
  13. NHS (UK). Vitamin A. Page last reviewed 3 August 2020 (version read). Read 2026-10-23.
  14. NHS (UK). B vitamins and folic acid. Page last reviewed 3 August 2020 (version read). Read 2026-10-23.
  15. Department of Health (UK). Dietary Reference Values: A Guide. HMSO, 1991. 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.