2.6 Understanding Dietary Reference Intakes

Dietary Reference Intakes (DRI) are the recommendation levels for specific nutrients and consist of a number of different types of recommendations. The link below takes you to the tables that many people commonly associate with the DRIs, but the DRIs are more than just numbers in a table.

The Dietary Guidelines discussed in section 2.3 provide qualitative advice to the public about diet and chronic disease prevention and maintaining health.  The Dietary Reference Intakes provide quantitative advice to professionals about amounts of nutrients or food components that are found in a healthy diet.

Dietary Reference Intakes: A Brief Overview

“Dietary Reference Intakes” (DRI) is an umbrella term for four reference values:

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

The DRIs are not minimum or maximum nutritional requirements and are not intended to fit everybody. They are to be used as guides only for the majority of the healthy population.^[1] DRIs are important not only to help the average person determine whether their intake of a particular nutrient is adequate, they are also used by health-care professionals and policy makers to determine nutritional recommendations for special groups of people who may need help reaching nutritional goals. This includes people who are participating in programs such as the Special Supplemental Food Program for Women, Infants, and Children. The DRI is not appropriate for people who are ill or malnourished, even if they were healthy previously.

Determining Dietary Reference Intakes

Each DRI value is derived in a different way.

Estimated Average Requirements. The EAR for a nutrient is determined by a committee of nutrition experts who review the scientific literature to determine a value that meets the requirements of 50 percent of people in their target group within a given life stage and for a particular sex. The requirements of half of the group will fall below the EAR and the other half will be above it. It is important to note that, for each nutrient, a specific bodily function is chosen as the criterion on which to base the EAR. For example, the EAR for calcium is set using a criterion of maximizing bone health. Thus, the EAR for calcium is set at a point that will meet the needs, with respect to bone health, of half of the population. EAR values become the scientific foundation upon which RDA values are set.

Recommended Daily Allowances. Once the EAR of a nutrient has been established, the RDA can be mathematically determined. While the EAR is set at a point that meets the needs of half the population, RDA values are set to meet the needs of the vast majority (97 to 98 percent) of the target healthy population. It is important to note that RDAs are not the same thing as individual nutritional requirements. The actual nutrient needs of a given individual will be different than the RDA. However, since we know the RDA meets 97 to 98 % of the populations’ needs, we can assume that if a person is consuming the RDA of a given nutrient, they are most likely meeting their nutritional need for that nutrient. The important thing to remember is that the RDA is meant as a recommendation and meeting the RDA means it is very likely that you are meeting your actual requirement for that nutrient.

This graph illustrates the risks of nutrient inadequacy and nutrient excess as we move from a low intake of a nutrient to a high intake. Starting on the left side of the graph, you can see that when you have a very low intake of a nutrient, your risk of nutrient deficiency is high. As your nutrient intake increases, the chances that you will be deficient in that nutrient decrease. The point at which 50 percent of the population meets their nutrient need is the EAR, and the point at which 97 to 98 percent of the population meets their needs is the RDA. The UL is the highest level at which you can consume a nutrient without it being too much—as nutrient intake increases beyond the UL, the risk of health problems resulting from that nutrient increases.

Other Quantitative Dietary Recommendations

Acceptable Macronutrient Distribution Ranges

The Acceptable Macronutrient Distribution Range (AMDR) is the calculated range of how much energy from carbohydrates, fats, and protein is recommended for a healthy diet. People who do not reach the AMDRs for their target group increase their risk of developing health complications.

Table 2.61 AMDR Values for Adults^[2]

Estimated Energy Requirement

Estimated Energy Requirement (EER) is the estimated number of calories needed to maintain caloric balance. Using weight as a reference, this means you are taking in no more calories, and also no fewer calories, than are needed to maintain that exact weight. To gain weight, you’d need to consume more than your EER, and to lose weight you’d need to consume less than your EER. Unlike some of the other DRIs, EER is individual-specific and is based on calculations that take into account multiple variables, including an individual’s energy intake, energy expenditure, age, sex, weight, height, and physical activity level^[3]. We’ll discuss EER more in chapter 9, when we talk about energy balance.

Tips for Using the Dietary Reference Intakes to Plan Your Diet

You can use the DRIs to help assess and plan your diet. Keep in mind when evaluating your nutritional intake that the values established have been devised with an ample safety margin and should be used as guidance for optimal intakes. In addition, the values are meant to assess and plan average intake over time; that is, you do not need to meet these recommendations every single day—meeting them on average over several days is sufficient.

Requirements vs. Recommendations

It’s important to understand that the DRIs are set to protect the health of a whole population. A single individual’s dietary needs may be higher or lower than the DRI.  This is why the DRIs are recommendations, not requirements. There is a distinct difference between a requirement and a recommendation. For instance, the DRI for vitamin D is a recommended 600 international units each day. However, in order to find out your true personal requirements for vitamin D, a blood test is necessary. The blood test will provide an accurate reading from which a medical professional can gauge your required daily vitamin D amounts. This may be considerably more or less than the DRI, depending on what your level actually is.

Nevertheless, if you are consuming the RDA (or AI) for a nutrient, on average, you can be reasonably sure (97-98% sure) that you’re getting an adequate amount of that nutrient.