How Mineral Requirements Are Set: EAR, RDA, AI, UL and the Evidence Behind Them
How expert committees set mineral intake numbers: EAR, RDA, AI and UL, which studies they use for calcium, iron, zinc, selenium and iodine, and what the numbers cannot tell you.
Content last updated . This page has not been medically reviewed.
These numbers describe healthy populations. They are not a prescription for any one person, and a clinician or pharmacist is the right person to ask about your own situation. [1][2]
The terms, as the sources define them
The United States and Canada use Dietary Reference Intakes (DRIs); the European Food Safety Authority (EFSA) uses Dietary Reference Values (DRVs); the UK uses its own terms. The ideas match even where the names differ.| US and Canada | EU (EFSA) | What it means |
|---|---|---|
| Estimated Average Requirement (EAR) | Average Requirement (AR) | The intake estimated to meet the needs of half of healthy people in a group [1][3] |
| Recommended Dietary Allowance (RDA) | Population Reference Intake (PRI) | Enough for nearly all (97 to 98 percent) healthy people in a group [1][2] |
| Adequate Intake (AI) | Adequate Intake (AI) | A judgment-based value used when an EAR cannot be set, drawn from observed intakes of apparently healthy people [1][2] |
| Tolerable Upper Intake Level (UL) | Tolerable Upper Intake Level (UL) | The highest daily intake likely to pose no risk of harm for almost everyone in the group; not a target [1][4] |
The UK's Reference Nutrient Intake (RNI) follows the same logic: enough to meet the needs of nearly all (97.5 percent) of a group, and not a minimum target. [5] For how these differ from the percent Daily Value on a label, see RDA, AI, DV and UL.
From "half of people" to "nearly everyone"
When enough data exist, the RDA is the EAR plus two standard deviations. When the spread is unknown, a 10 percent coefficient of variation is ordinarily assumed. [1] EFSA uses the same idea for the PRI. [2] The chain has a weak link: if an EAR cannot be set, no RDA is set, and an AI is used instead. [1] EFSA says likewise that no PRI can be derived without an AR. [2]What studies the committees used, mineral by mineral
EFSA's 2017 summary shows how different the starting points are.| Mineral | Main approach described by EFSA | What the source says about the basis |
|---|---|---|
| Calcium | Calcium balance studies in North American adults aged 25 and over: the intake at which intake equals losses was 715 mg a day, which led to an AR of 750 mg and a PRI of 950 mg [6] | Bone density, fractures and heart outcomes could not be used because of confounders and inconsistent findings [6] |
| Iron | A factorial approach: obligatory losses plus an estimate of absorption, with a target serum ferritin of 30 mcg/L [6] | Health outcomes could not be used because intake correlates poorly with iron status [6] |
| Zinc | Physiological requirement plus an absorption model; PRIs are given for four levels of dietary phytate (a plant compound that reduces absorption) [6] | One number does not fit every diet [6] |
| Selenium | The level at which plasma selenoprotein P stops rising, a marker of selenium supply to tissues [6] | Data were too uncertain for an AR, so an AI of 70 mcg a day was set for adults [6] |
| Iodine | A urinary iodine threshold linked to low goiter rates in surveys [6] | An AI of 150 mcg a day for adults [6] |
| Magnesium | Observed intakes in several EU countries [6] | An AI; EFSA called serum magnesium a questionable marker of intake or status [6] |
A biomarker is a measurement such as blood ferritin or urinary iodine. A change in a biomarker is not the same as a health outcome, which is one reason these values are described as estimates.
How upper levels are set
An upper level is a risk assessment. When possible the UL starts from the highest intake with no observed adverse effect (the NOAEL); if none exists, a lowest-observed-adverse-effect level (LOAEL) may be used. [7] An uncertainty factor is then applied: the larger the uncertainty, the smaller the UL. [8] EFSA's UL is the maximum level of total chronic daily intake from all dietary sources not expected to pose a risk. [4]Three cautions follow:
- A UL is not advice to reach it. The US and Canadian committee wrote that there is no established benefit for healthy people who exceed the recommended intake. [1]
- No UL does not mean safe. Where data are insufficient, no UL is set; this signals caution and does not mean high intakes carry no risk. [1] For iron and manganese, EFSA publishes a "safe level of intake" instead, which has more limited uses than a UL. [4]
- Some ULs cover only supplements. The magnesium UL in both the Canadian table and the EFSA summary applies to supplemental or added magnesium, not magnesium naturally in food. [9][4]
Why two bodies can differ
Different committees weigh different studies in different years. Canada's table notes that calcium values published in 2011 replaced the 1997 values. [9] For adults, the Canadian table lists a calcium RDA of 1,000 mg a day for ages 19 to 30, while EFSA's PRI for adults aged 25 and over is 950 mg. [9][6] See the side-by-side table on Mineral Intake References Compared.Frequently asked questions
What is the difference between an RDA and an AI?
An RDA comes from an estimated average requirement plus a margin so that nearly all healthy people are covered. An AI is used when there is not enough evidence to set an average requirement, and it is based on observed intakes of healthy groups. [1]
Is the RDA the minimum I need?
No. The RDA is set above the average requirement so that nearly all healthy people in a group are covered, so many people need less. The British Nutrition Foundation says the same of UK RNIs: they are not minimum targets. [1][5]
Does an upper limit mean everything below it is safe?
Not necessarily. A UL is the highest daily intake likely to pose no risk for almost everyone in a group of healthy people; it does not account for medicines or illness. A clinician or pharmacist can say what applies to you. [1][2]
Why are there no upper limits for some minerals?
When there is not enough evidence to set one, no UL is set, which calls for caution and does not show that high intakes are harmless. EFSA, for example, gives a "safe level of intake" for iron. [1][4]
Where can I find the actual numbers?
Official figures for adults from the US and Canada, the UK and the EU are compared in Mineral Intake References Compared, and age-by-age tables are in Mineral Intake Reference Tables.
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.
Limits and who should ask a clinician
- Healthy people only. The DRIs apply to the healthy population; people with diseases that affect absorption or treatments such as dialysis may have different needs and should get guidance from qualified medical and nutrition staff. [1] EFSA says people with diseases may have different needs and should ask health professionals. [2]
- Special groups. Vegetarian diets can raise the requirement: Canada's footnotes say iron needs are 1.8 times higher and zinc needs may be up to 50 percent higher for vegetarians. [9] See Mineral Needs Across Life Stages.
- Medicines, pregnancy, children, kidney or liver conditions, and before surgery. The reference values do not account for these. Ask a clinician or pharmacist first, and read Medication Interactions and Supplements Before Surgery.
- Product quality. An intake figure only helps if the label is accurate; see Quality Testing and Certifications.
References
- Institute of Medicine (1998). Introduction to Dietary Reference Intakes, in Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. National Academies Press. Read 2026-10-23.
- European Food Safety Authority. Dietary reference values (page last reviewed 5 August 2024). Read 2026-10-23.
- Health Canada. Dietary reference intakes tables: Overview (page dated 2025-11-19). Read 2026-10-23.
- European Food Safety Authority (August 2025). Overview on Tolerable Upper Intake Levels as derived by the Scientific Committee on Food and the EFSA NDA Panel. Read 2026-10-23.
- British Nutrition Foundation. Nutrient requirements (UK). Read 2026-10-23.
- European Food Safety Authority (2017). Dietary Reference Values for nutrients: Summary report. EFSA Supporting Publication 2017:e15121. Read 2026-10-23.
- Institute of Medicine (1998). Risk assessment and food safety, in Dietary Reference Intakes: A Risk Assessment Model for Establishing Upper Intake Levels for Nutrients. National Academies Press. Read 2026-10-23.
- Institute of Medicine (1998). Steps in the development of the Tolerable Upper Intake Level, in Dietary Reference Intakes: A Risk Assessment Model for Establishing Upper Intake Levels for Nutrients. National Academies Press. Read 2026-10-23.
- Health Canada. Dietary reference intakes tables: Reference values for elements (page dated 2025-11-19). Read 2026-10-23.