The Dietary Reference Intake can be defined a system of nutrition recommendations that estimates the amounts of nutrients required to prevent deficiencies and maintain optimal Health.
The DRI includes some concepts that sometimes are used as equivalents, when they are not. In other cases, the same concept receive different names, depending of the source of the article you are reading.
DRIs consists of four dietary reference standards:
1.- Estimated Average Requirement (EAR): Average daily nutrient intake level estimated to meet the requirement of one half of the healthy individuals in a specific age and gender group.
2.- Recommended Dietary Allowance (RDA): Average daily Dietary intake level that is sufficient to meet the nutrient requirements of nearly all (97-98%) individuals (EAR+2DS) on each life state and gender group. It is approximately 20 % higher than the EAR. RDA are printed in food labels in the United States and Canada. (The definition of RDA is similar to the definition of Recommended Nutrient Intake (RNI) used by the World Health Organization and other international organizations).
3.- Adequate Intake (AI): Estimation of nutrient intake in healthy people (used when EAR and RDA are not known)
4.- Tolerable Upper Intake Level (UL): Highest average daily intake level from food, water and supplements that is likely to pose no risk of adverse health effect from excess in almost all apparently healthy individuals in an age and gender specific population group. (This concept is important mainly in relation to nutritional supplements, since the ingestion of natural foods is regulated in the body through mechanisms of absorption and excretion), In absence of observations of known adverse effects, it is used a default value of 10 times de Recommended Dietary Allowance.
More information about these reference standards can be found at:
Dietary Reference Intake
Reference dialy Intake
Interactive DRI for health care professionals
Yates, A.A.: Dietary Reference Intakes –What is new and how to use them (Power point presentation)
Who Experts Committee:
Vitamin and Mineral requirements in human nutrition
World Health Organization, 2004