2.5 – Understanding Dietary Reference Intakes

Dietary Reference Intakes: A Brief Overview

Dietary Reference Intakes (D.R.I.) are the recommendation levels for specific nutrients and consist of a number of different types of recommendations. This D.R.I. system is used in both the United States and Canada.

“Dietary Reference Intakes” (D.R.I.) is an umbrella term for four reference values:

• Estimated Average Requirements (E.A.R.)
• Recommended Dietary Allowances (R.D.A)
• Adequate Intakes (A.I.)
• Tolerable Upper Intake Levels (U.L.)

The D.R.I.s 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.

D.R.I.s are important not only to help the average person determine whether their intake of a particular nutrient is adequate, but 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 D.R.I. is not appropriate for people who are ill or malnourished, even if they were healthy previously.

^{1 Deng S, West BJ, Jensen CJ. A Quantitative Comparison of Phytochemical Components in Global Noni Fruits and Their Commercial Products. Food Chemistry. 2010; 122(1), 267–70. Accessed June 18, 2019.}

Determining Dietary Reference Intakes

Each D.R.I. value is derived in a different way. See below for an explanation of how each is determined:

1. Estimated Average Requirements. The E.A.R. 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 E.A.R. 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 E.A.R. For example, the E.A.R. for calcium is set using a criterion of maximizing bone health. Thus, the E.A.R. for calcium is set at a point that will meet the needs, with respect to bone health, of half of the population. E.A.R. values become the scientific foundation upon which R.D.A values are set.
2. Recommended Daily Allowances. Once the E.A.R. of a nutrient has been established, the R.D.A can be mathematically determined. While the E.A.R. is set at a point that meets the needs of half the population, R.D.A 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 R.D.As are not the same thing as individual nutritional requirements. The actual nutrient needs of a given individual will be different than the R.D.A. However, since we know that 97 to 98 percent of the population’s needs are met by the R.D.A, we can assume that if a person is consuming the R.D.A of a given nutrient, they are most likely meeting their nutritional need for that nutrient. The important thing to remember is that the R.D.A is meant as a recommendation and meeting the R.D.A means it is very likely that you are meeting your actual requirement for that nutrient.

Understanding the Difference

There is a distinct difference between a requirement and a recommendation. For instance, the D.R.I. 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 D.R.I., depending on what your level actually is.

1. Adequate Intake. A.I.s are created for nutrients when there is insufficient consistent scientific evidence to set an E.A.R. for the entire population. As with R.D.As, A.I.s can be used as nutrient-intake goals for a given nutrient. For example, there has not been sufficient scientific research into the particular nutritional requirements for infants. Consequently, all of the D.R.I. values for infants are A.I.s derived from nutrient values in human breast milk. For older babies and children, A.I. values are derived from human milk coupled with data on adults. The A.I. is meant for a healthy target group and is not meant to be sufficient for certain at-risk groups, such as premature infants.
2. Tolerable Upper Intake Levels. The U.L. was established to help distinguish healthful and harmful nutrient intakes. Developed in part as a response to the growing usage of dietary supplements, U.L.s indicate the highest level of continuous intake of a particular nutrient that may be taken without causing health problems. When a nutrient does not have any known issue if taken in excessive doses, it is not assigned a U.L. However, even when a nutrient does not have a U.L. it is not necessarily safe to consume in large amounts.

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 E.A.R., and the point at which 97 to 98 percent of the population meets their needs is the R.D.A. The U.L. is the highest level at which you can consume a nutrient without it being too much—as nutrient intake increases beyond the U.L., the risk of health problems resulting from that nutrient increases.

Source: Dietary Reference Intakes Tables and Application. The National Academies of Science, Engineering, and Medicine. Health and Medicine Division. Accessed November 22, 2017.

The Acceptable Macronutrient Distribution Range (A.M.D.R.) is the calculated range of how much energy from carbohydrates, fats, and protein is recommended for a healthy diet adequate of the essential nutrients and is associated with a reduced risk of chronic disease. The ranges listed in Table 12.2.1 allows individuals to personalize their diets taking into consideration that different subgroups in a population often require different requirements. The D.R.I. committee recommends using the midpoint of the A.M.D.R.s as an approach to focus on moderation.