Dietary Reference Intake (DRI) is a collection of four reference values related to intakes of nutrients. The four values include:

• Estimated Average Requirements (EAR)
  
• Recommended Dietary Allowances (RDA)
  
• Adequate Intakes (AI)
  
• Tolerable Upper Intake Levels (UL)

You may remember the acronym RDA as the only standard value written about on food labels and nutrition charts. The RDA system was updated in the mid-1990s, with the introduction of the DRI system.

All of the DRI terms relate to daily nutrient intake. Different nutrients will have different values associated, based on the current research available. UL limits are established to prevent toxicity (overdose) issues. The Tolerable Upper Intake Level is the highest amount of a nutrient you can likely intake on a daily basis without causing adverse health effects. The AI limit is established when there is insufficient data to set an RDA limit. The RDA and EAR limits are similar, differing only in the level of the population “covered” by the suggested dose.

• The RDA is the daily intake of a nutrient sufficient to meet the requirements of ~98% of healthy Americans (per age and sex).
  
• The EAR is the intake level required to meet the needs of ~50% of healthy Americans (per age and sex).

Why are there so many terms? The Food and Nutrition Board is a group of expert who meet periodically to review nutrition research and discuss the current nutrient standards. This board has been meeting since 1941, and was responsible for the development of the RDA and DRIs. In recent times, some scientists became concerned as to what level the standard should be set for nutrients. If the suggested daily “dose” is too high, then some people may actually be consuming too much of a given nutrient. If it is too low, the part of the population may be encouraged to court deficiency. At this point, the four levels (the DRIs) are issued for all major micronutrients whenever there is sufficient research to support a particular level or limit.

DRI recommendations are developed for specific sex, age, and health status categories (pregnant, breastfeeding). The data are organized in tabular form; data pages for macronutrients (carbohydrates, fiber, etc.) and micronutrients (specific vitamins and minerals) are available at:

http://fnic.nal.usda.gov/nal_display/index.php?info_center=4&tax_level=3&tax_subject=256&topic_id=1342&level3_id=5140.