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Glossary

What is Adequate Intake (AI) in nutrition?

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

An Adequate Intake (AI) is the daily amount of a nutrient assumed to be enough for nutritional adequacy, set when the evidence is too limited for an RDA. Biotin, vitamin K and potassium have only AIs; for adults the biotin AI is 30 mcg a day.1,2,3

Key facts

  • AIs are usually based on what healthy people actually take in, or for infants on the intake of healthy breastfed babies.2,4,5
  • NIH calls the vitamin K AI only an estimate of need.2
  • Adult AIs include vitamin K at 120 mcg for men and 90 mcg for women, and potassium at 3,400 mg and 2,600 mg.2,3
  • The potassium AIs date from 2019, when a National Academies committee found too few data to set an Estimated Average Requirement.3
  • A label's Daily Value can differ from today's AI: potassium's Daily Value is 4,700 mg, above both adult AIs.3,6

AI versus RDA

Both are daily amounts meant for healthy people, and both come from the Food and Nutrition Board of the National Academies. The difference is the evidence behind them. An RDA is built on an Estimated Average Requirement, the intake that meets the needs of half of healthy people, and is set to cover nearly all. When no such requirement can be estimated, the board sets an AI instead.1,5

How the two compare1,2,4,7
QuestionRDAAI
What it rests onAn Estimated Average Requirement, set higher to cover nearly all healthy peopleUsual intakes of healthy people, or of healthy breastfed infants
How sure it isMeets the needs of 97 to 98 percent of healthy peopleAssumed to be adequate; NIH calls one an estimate of need
ExamplesVitamin C, iron, zinc, folateBiotin, vitamin K, potassium, chromium

Nutrients with only an AI

  • Biotin: 30 mcg a day for adults, and 35 mcg while breastfeeding.1
  • Vitamin K: 120 mcg for men and 90 mcg for women aged 19 and over.2
  • Potassium: 3,400 mg for men and 2,600 mg for women aged 19 and over.3
  • Chromium: 35 mcg for men and 25 mcg for women aged 19 to 50.4

Infants often get AIs too. The folate AI for babies up to 6 months is 65 mcg DFE, equal to the average intake of healthy breastfed infants.5

AIs and the Daily Value

Where a nutrient has only an AI, the Daily Value often matches an adult AI: biotin's is 30 mcg and vitamin K's is 120 mcg. Potassium is the one to know. Its Daily Value is 4,700 mg, while the AIs set in 2019 are 3,400 mg for men and 2,600 mg for women, so 100% on a label is more than either.1,2,3,6

When an AI does not apply

The potassium AIs are for healthy people. NIH notes they do not apply to people whose bodies excrete potassium poorly because of a medical condition such as kidney disease, or because of medicines that impair potassium excretion. In either case, ask your doctor before taking potassium supplements.3

Questions people ask

Is an AI less reliable than an RDA?

It rests on less evidence. An AI is set when there are not enough data for an RDA, and intake at that level is assumed, rather than shown, to be adequate.1,7

Does a nutrient with an AI also have an upper limit?

Not always. The AI and the Tolerable Upper Intake Level are separate. Biotin has an AI but no upper limit, because there is no evidence in humans that it is toxic at high intakes.1

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Sources

  1. NIH Office of Dietary Supplements. Biotin: Fact Sheet for Health Professionals. Updated January 10, 2022. Opened 2026-10-07.
  2. NIH Office of Dietary Supplements. Vitamin K: Fact Sheet for Health Professionals. Updated March 29, 2021. Opened 2026-10-07.
  3. NIH Office of Dietary Supplements. Potassium: Fact Sheet for Health Professionals. Updated June 2, 2022. Opened 2026-10-07.
  4. NIH Office of Dietary Supplements. Chromium: Fact Sheet for Health Professionals. Updated June 2, 2022. Opened 2026-10-07.
  5. NIH Office of Dietary Supplements. Folate: Fact Sheet for Health Professionals. Updated November 30, 2022. Opened 2026-10-07.
  6. U.S. Food and Drug Administration. Daily Value on the Nutrition and Supplement Facts Labels. Content current as of March 5, 2024. Opened 2026-10-07.
  7. NIH Office of Dietary Supplements. Vitamin C: Fact Sheet for Health Professionals. Updated July 31, 2025. Opened 2026-10-07.

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