How to read RDA, AI and UL — the reference values behind nutrient numbers
For reference only. This is not a diagnosis or a prescription. If you have concerns, talk to a doctor or pharmacist.
RDA and EAR
The Recommended Dietary Allowance (RDA) is the average daily intake level that is enough to meet the nutrient needs of nearly all (97–98 percent) healthy people in a group.
The RDA is calculated from the Estimated Average Requirement (EAR).
The EAR is the average daily intake level estimated to meet the needs of half of the healthy people in a group.
AI
When there is not enough scientific evidence to set an EAR, and so an RDA, an Adequate Intake (AI) is usually set instead.
For healthy breastfed infants, the AI is the average intake.
For other life-stage and gender groups, the AI is believed to cover the needs of all healthy people in those groups, but limited or uncertain data mean that the percentage of people it covers cannot be stated with confidence.
UL
The Tolerable Upper Intake Level (UL) is the highest level of daily intake that is likely to pose no risk of harmful health effects to almost all people in the general population.
Unless otherwise specified, the UL represents total intake from food, water, and supplements.
Because of a lack of suitable data, no UL has been set for some nutrients, such as vitamin K, thiamin, riboflavin, vitamin B12, pantothenic acid and biotin.
Where there is no UL, the source notes that extra caution may be warranted in consuming levels above recommended intakes.
What these values can and cannot tell one person
The RDA is not a useful reference standard for assessing one person’s intake: intake below the RDA cannot be assumed to mean that the person’s intake is inadequate.
When usual intake is below the AI, no conclusions can be drawn.
EU names for similar values
In the EU, EFSA’s Population Reference Intake (PRI) is the level of nutrient intake that is adequate for virtually all healthy people in a population group.
EFSA’s Average Requirement (AR) is the level of nutrient intake that is adequate for half of the healthy people in a population group, given a normal distribution of requirement.
EFSA’s Adequate Intake (AI) is a value estimated when a PRI cannot be established because an average requirement cannot be determined.
EFSA’s Tolerable Upper Intake Level is the maximum level of total chronic daily intake of a nutrient (from all sources) judged to be unlikely to pose a risk of adverse health effects to humans.
Sources
- EFSA — Dietary Reference Values for nutrients: Summary report (2017)
- NASEM Dietary Reference Intakes summary tables (Appendix J, 2019)
- NASEM — Dietary Reference Intakes: Applications in Dietary Assessment (2000), Chapter 3
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