The Dietary Reference Intake framework, which is used to plan and assess diets in people without health conditions, contains several “reference values”. These include the recommended dietary allowance (RDA) as well as the estimated average requirement, adequate intake, and tolerable upper intake level.^[1][2][3][4]

The RDA for a specific nutrient is the daily intake amount that is estimated to meet the known nutritional requirements of nearly all (97.5%) people without health conditions. RDA values for some nutrients are also dependent on age, sex, and pregnancy,^[1][2] but an RDA value stated on food packaging typically refers to the RDA for non-pregnant adults ages 19 to 50.^[5] For the food-based dietary guidelines across all countries in the United Nations, see here.

To ensure that people obtain sufficient quantities of specific nutrients, RDA values are two standard deviations above the estimated average requirement. Therefore, people who consume nutrients in quantities at or above the RDA have a low probability of inadequacy of that nutrient. Consequently, RDA values can help plan nutritionally adequate diets for individuals.

RDA values are derived from large-scale population-based observational studies. However, due to insufficient evidence, an RDA value has not been defined for all nutrients because an estimated average requirement value does not always exist. In such cases, nutrients are assigned an adequate intake value, which is the level of intake for a specific nutrient that may ensure nutritional adequacy in most people without health conditions, based on the limited evidence that exists.

The terminology used to describe the RDA varies between countries. For example, while recommended dietary allowance (RDA) is used in the U.S. and Canada, it is called the reference nutrient intake (RNI) in the U.K. and the population reference intake (PNI) in the EU.^[4] Sometimes the phrases recommended daily allowance or recommended dietary intake (RDI) are also used. However, despite the different terminology, their application is the same.

RDA values for specific nutrients can vary between countries and may change as new evidence emerges. In the U.S., reference values to help plan nutritionally adequate diets for individuals — either RDA or adequate intake — have been developed for total energy intake,^[6][7] macronutrients (carbohydrates, fats, and protein),^[7] fatty acids,^[7] cholesterol,^[7] amino acids,^[7] fiber,^[8][7] and several micronutrients (vitamins and minerals).^{[9][10][11][12][13]}