Estimated Average Requirement (EAR), Recommended Dietary Allowance (RDA), and Adequate Intake (AI) are all part of the Daily Reference Intakes (RDIs). The RDIs are guidelines based on the best scientific evidences available that consider nutrient needs for healthy populations (McArdle, Katch, & Katch 2013). Where evidence is lacking best judgement were made based on observations and experimentally derived approximations (Otten, Hellwig & Meyers 2006). Among other lifestyle factors, diet is one of the leading causes of death and illness (Danaei et al., 2009; Park, 2014; Simon, 2014). Given this, RDIs focus on health maintenance and disease prevention for dietary prone disease states (Dietary Reference Intakes n.d.; McArdle, Katch, & Katch 2013). The DRIs are not meant to be applicable to people who are malnourished, have special circumstances, or ill (Otten, Hellwig & Meyers 2006).
The Estimated Average Requirement (EAR) is by definition the estimated nutrient intake that will meet half the daily requirements of healthy individuals in a specific life stage or gender group (McArdle, Katch, & Katch 2013). Noted within EAR is specific measures for energy intake noted as Estimated Energy Requirement (EER). EER is the estimated average energy requirement that is required by a health adult of a specific age, gender, weight, height, and physical activity level (Otten, Hellwig & Meyers 2006). EAR is in effect a measure of the median requirement, not average (Otten, Hellwig & Meyers 2006). Given this, the EAR exceeds or falls short of the needs of parts of the group (Otten, Hellwig & Meyers 2006). The EAR is used a tool for measuring the nutritional adequacy of groups – not individuals (Otten, Hellwig & Meyers 2006). The recommended daily allowance (RDA) is appropriate to apply to individuals.
The RDA is the average daily nutrient intake that meets the need of nearly 98% of healthy individuals in a specific life stage or gender group (McArdle, Katch, & Katch 2013). Since the RDA exceeds the requirements for almost all person in the population groups specified it can be used as a guide for individual nutrient intake (Otten, Hellwig & Meyers 2006). Usually intakes at or just below the RDA cannot be viewed as inadequate (Otten, Hellwig & Meyers 2006). Probably an individual falling at the mean between the EAR and RDA would need improvement (Otten, Hellwig & Meyers 2006). Therefore, using both the EAR and RDA will help in the planning paradigm for an individual. If no EAR can be set no RDA will be calculated as the RDA is the EAR plus 2 standard deviations (McArdle, Katch, & Katch 2013; Otten, Hellwig & Meyers 2006). When no RDA is available one may look to adequate intake (AI) for nutrient reference.
The AI is estimated when no RDA exists (McArdle, Katch, & Katch 2013). These values are based on observed or experimentally derived approximations based on healthy individuals from a cohort who are thought to have an adequate nutritional state (McArdle, Katch, & Katch 2013; Otten, Hellwig & Meyers 2006). Examples of an adequate nutritional state include normal growth, normal nutrient plasma levels, and other marker of good health (Otten, Hellwig & Meyers 2006). The AI is expected to meet or exceed the nutritional need of an individual in a specific life stage or gender group. As such, it may be used when the RDA is not present to assess the adequacy of the individual nutritional status for a nutrient.
Danaei, Goodarz, et al. The Preventable Causes of Death in the United States: Comparative Risk Assessment of Dietary, Lifestyle, and Metabolic Risk Factors. 6 Apr. 2009, www.ncbi.nlm.nih.gov/pmc/articles/PMC2667673/.
Dietary Reference Intakes. www.nal.usda.gov/fnic/dietary-reference-intakes. Accessed 7 Feb. 2018.
McArdle, William D., et al. Sports and Exercise Nutrition. 4th ed., Lippincott Williams and Wilkins, 2013.
Otten, Jennifer J., et al. Dietary Reference Intakes: the Essential Guide to Nutrient Requirements. National Academy Press, 2006.
Park , Alice. Preventable Deaths: CDC Says 40% of Deaths Each Year Can Be Avoided. 1 May 2014, time.com/84514/nearly-half-of-us-deaths-can-be-prevented-with-lifestyle-changes/. Accessed 7 Feb. 2018.
Simon, Stacy. CDC: Lifestyle Changes Can Reduce Death from Top 5 Causes. 4 June 2014, www.cancer.org/latest-news/cdc-lifestyle-changes-can-reduce-death-from-top-5-causes.html. Accessed 7 Feb. 2018.