The Dietary Reference Intake is a system of nutrition recommendations from the Institute
of Medicine of the U.S. National Academy of Sciences. The DRI provides several different
types of reference value: Estimated Average Requirements, expected to
satisfy the needs of 50% of the people in that age group based on a review of the scientific
literature. Recommended Dietary Allowances, the daily
dietary intake level of a nutrient considered sufficient by the Food and Nutrition Board
to meet the requirements of 97.5% of healthy individuals in each life-stage and sex group.
It is calculated based on the EAR and is usually approximately 20% higher than the EAR.
Adequate Intake, where no RDA 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, to caution against excessive intake of nutrients that
can be harmful in large amounts. This is the highest level of daily consumption that current
data have shown to cause no side effects in humans when used indefinitely without medical
supervision. Acceptable Macronutrient Distribution Ranges,
a range of intake specified as a percentage of total energy intake. Used for sources of
energy, such as fats and carbohydrates. The DRI system is used by both the United
States and Canada and is intended for the general public and health professionals. Applications
include: Composition of diets for schools, prisons,
hospitals or nursing homes Industries developing new food stuffs
Healthcare policy makers and public health officials
The DRI was introduced in 1997 in order to broaden the existing guidelines known as Recommended
Dietary Allowances. The current DRI values differ from those used in nutrition labeling
in the U.S. and Canada, which uses Reference Daily Intakes based on RDAs from 1968.
History The recommended dietary allowance was developed
during World War II by Lydia J. Roberts, Hazel Stiebeling, and Helen S. Mitchell, all part
of a committee established by the United States National Academy of Sciences in order to investigate
issues of nutrition that might "affect national defense". 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. 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, United States Department of Agriculture 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 DRI values differ from those used
in nutrition labeling in the U.S. and Canada, which uses Reference Daily Intakes based on
RDAs from 1968. Vitamins and minerals
EARs, RDA/AIs and ULs for an average healthy 44-year old male are shown below. EARs shown
as "NE" have not yet been established or not yet evaluated. 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 may be much different.
EAR: Estimated Average Requirements; RDA: Recommended Dietary Allowances; AI: Adequate
Intake; UL: Tolerable upper intake levels.
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
RDA/AI is shown below for males and females aged 40–50 years.
Calculating the RDA The equations used to calculate the RDA are
as follows: "If the standard deviation of the EAR is available
and the requirement for the nutrient is symmetrically distributed, the RDA is set at two SDs above
the EAR:
If data about variability in requirements are insufficient to calculate an SD, a coefficient
of variation for the EAR of 10 percent is assumed, unless available data indicate a
greater variation in requirements. If 10 percent is assumed to be the CV, then twice that amount
when added to the EAR is defined as equal to the RDA. The resulting equation for the
RDA is then
This level of intake statistically represents 97.5 percent of the requirements of the population."
Recent developments In September 2007, the Institute of Medicine
held a workshop entitled “The Development of DRIs 1994–2004: Lessons Learned and New
Challenges.” At that meeting, several speakers stated that the current Dietary Recommended
Intakes were largely based upon the very lowest rank in the quality of evidence pyramid, that
is, opinion, rather than the highest level – randomized controlled clinical trials.
Speakers called for a higher standard of evidence to be utilized when making dietary recommendations.
See also Healthy diet
Acceptable daily intake — upper limit on intake
Dietary Reference Values — recommended dietary requirements
Reference Intakes - a system of nutrient labeling used in Europe
Vitamin poisoning Canada's Food Guide
Food guide pyramid Dietary mineral
Essential amino acid Essential fatty acid
Essential nutrient Food composition
References
Further reading Nestle, Marion. Food Politics. Berkeley: University
of California Press. ISBN 0-520-22465-5. Panel on Micronutrients, Subcommittees on
Upper Reference Levels of Nutrients and of Interpretation and Use of Dietary Reference
Intakes, and the Standing Committee on the Scientific Evaluation of Dietary Reference
Intakes. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper,
Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington DC:
National Academy Press. ISBN 0-309-07279-4. External links
US Government Food and Nutrition Information Center list of Dietary Reference Intakes and
Recommended Dietary Allowances USDA RDA chart
USDA Dietary Reference Intakes Article comparing recommended amounts of vitamins
and minerals in different countries from the European Union