Dietary reference intake
The Dietary Reference Intake is a system of nutrition recommendations from the Institute of Medicine of the USA National Academy (IOM). The DRI system is used by both the United States and Canada. It is intended for the general public and health professionals.  Applications include:
- Food labels in the United States and Canada
- Composition of diets for schools, prisons, hospitals or nursing homes
- Industries developing new food stuffs
- Healthcare policy makers and public health officials
In 1997, at the suggestion of the Institute of Medicine of the National Academy, the RDA became one part of a broader, more detailed set of dietary guidelines, called the Dietary Reference Intake.

# History
The Recommended Dietary Allowance (RDA) was developed during World War II by Lydia J. Roberts, Hazel K. Stiebeling and Helen S. Mitchell, all part of a committee established by the U.S. National Academy of Sciences in order 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 in order to make it easier for people to receive their RDAs of each nutrient.

# Current recommendations
The current Dietary Reference Intake recommendation is composed of:
- Estimated Average Requirements (EAR), expected to satisfy the needs of 50% of the people in that age group.
- Reference Daily Intake (RDI), the daily dietary intake level of a nutrient considered sufficient to meet the requirements of nearly all (9798%) healthy individuals in each life-stage and gender group.
- Adequate Intake (AI), where no RDI has been established, but the amount established is somewhat less firmly believed to be adequate for everyone in the demographic group.
- Tolerable upper intake levels (UL), to caution against excessive intake of nutrients (like vitamin D) that can be harmful in large amounts.
The RDI is used to determine the Recommended Daily Value (RDV) which is printed on food labels in the U.S. and Canada.

## Vitamins and minerals
RDI/AIs and ULs for a 25-year old male are shown below.  ULs shown as "ND" could not be determined, and it is recommended that intake from these nutrients be from food only, to prevent adverse effects.  Amounts and "ND" status for other age and gender groups, pregnant women, lactating women, and breastfeeding infants are different.
a From pill only, not including food and water intake.
It is also recommended that the following substances not be added to food or dietary supplements. Research has been conducted into adverse effects, but was not conclusive in many cases:

## Macronutrients
RDI/AI is shown below for males aged 19-30 years.