Reference Daily Intake

The Reference Daily Intake or Recommended Daily Intake (RDI) is the daily intake level of a nutrient that is considered to be sufficient to meet the requirements of 97–98% of healthy individuals in every demographic in the United States (where it was developed, but has since been used in other places).

The RDI is used to determine the Daily Value (DV) of foods, which is printed on nutrition facts labels in the United States and Canada, and is regulated by the Food and Drug Administration (FDA) and Health Canada respectively.

The RDI is based on the older Recommended Dietary Allowance (RDA) from 1968; newer RDAs have since been introduced in the Dietary Reference Intake system, but the RDI is still used for nutrition labeling.

Food labeling reference tables
DVs used by the FDA for the following macronutrients are Daily Reference Values (DRV).

The following table lists the DVs based on a caloric intake of 2,000 cal (8400 kJ), for adults and children four or more years of age.

For vitamins and minerals, the RDIs are given in the following table, along with the more recent RDAs of the Dietary Reference Intakes (maximized over sex and age groups):

History
The RDA was developed during World War II by Lydia J. Roberts, Hazel Stiebeling and Helen S. Mitchell, all part of a committee established by the U.S. National Academy of Sciences to investigate issues of nutrition that might "affect national defense" (Nestle, 35). The committee was renamed the Food and Nutrition Board in 1941, after which they began to deliberate on a set of recommendations of a standard daily allowance for each type of nutrient. The standards would be used for nutrition recommendations for the armed forces, for civilians, and for overseas population who might need food relief. Roberts, Stiebeling, and Mitchell surveyed all available data, created a tentative set of allowances for "energy and eight nutrients", and submitted them to experts for review (Nestle, 35). The final set of guidelines, called RDAs for Recommended Dietary Allowances, were accepted in 1941. The allowances were meant to provide superior nutrition for civilians and military personnel, so they included a "margin of safety". Because of food rationing during the war, the food guides created by government agencies to direct citizens' nutritional intake also took food availability into account.

The Food and Nutrition Board subsequently revised the RDAs every five to ten years. In the early 1950s, USDA nutritionists made a new set of guidelines that also included the number of servings of each food group to make it easier for people to receive their RDAs of each nutrient.

In 1997, at the suggestion of the Institute of Medicine of the National Academy, RDA became one part of a broader set of dietary guidelines called the Dietary Reference Intake used by both the United States and Canada.

Disputed value
The value of RDA/RDIs is disputed among nutritionists. Indeed, even the "definition of RDAs and their relevance to health" is disputed.

e.g., the daily maximum for some nutrients, like sodium are higher in the U.S. than in other parts of the developed world, and are far above established safe minimums. For instance, the National Research Council (in the USA) has found that 500 mg of sodium per day (approximately the amount in a quarter-teaspoon of table salt) is a safe minimum level. In the United Kingdom, the daily allowance for salt is 6g (approximately 2.5 teaspoons, about the upper limit in the U.S.), but are still considered "too high".