Dietary Reference Intakes (DRI): An Overview

Dietary Reference Intakes (DRIs) are science-based recommendations for energy and nutrient intake. They help nutrition professionals assess diets, develop public health policies, and plan healthy eating patterns.

The most commonly used DRI values are summarized in Table 2.8.

 

The sections that follow explain each of these DRI values and how they are used in nutrition research, public health, and dietary planning.

Two DRI values relate to energy intake: the Estimated Energy Requirement (EER) and the Acceptable Macronutrient Distribution Range (AMDR). The EER is described first.

Estimated Energy Requirement (EER)

The Estimated Energy Requirement (EER) is the average number of calories a person needs each day to maintain health. It is estimated using age, sex, height, weight, and physical activity level.

For adults, the EER represents the calorie intake needed to maintain body weight. For children, adolescents, pregnant women, and lactating women, it also includes energy needed for growth, development, pregnancy, or milk production.

Because energy needs vary with physical activity and other individual factors, the EER should be viewed as a general estimate rather than a precise prescription.

 

Acceptable Macronutrient Distribution Ranges (AMDR)

The AMDR specifies the percentage of calories that should come from carbohydrates, fat, and protein. These ranges are broad enough to accommodate many healthy eating patterns, as illustrated in Figure 2.11.

 

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DRI for Nutrients: EAR, RDA, AI, and UL

Four DRI values are used to describe recommendations for nutrient intake:

• Estimated Average Requirement (EAR)
• Recommended Dietary Allowance (RDA)
• Adequate Intake (AI)
• Tolerable Upper Intake Level (UL)

These values vary by age, sex, and life stage and are summarized in DRI tables (Figure 2.12). The sections that follow explain what each value means and how it is used.

Estimated Average Requirement (EAR)

The Estimated Average Requirement (EAR) is the amount of a nutrient that meets the requirements of 50% of healthy people in a specific life-stage and sex group. Because individual nutrient needs vary, some people require less than the EAR, while others require more. The EAR represents the midpoint of this range of individual requirements.

To set an EAR, scientists review research on a nutrient and select a measurable biological function to serve as the benchmark. For example, the EAR for calcium is based on the intake needed to support bone health, a key and measurable function of calcium.

If everyone consumed only the EAR, about half of the population would not meet their needs. For this reason, the EAR is not intended as an intake goal for individuals. Instead, it is used primarily to calculate the Recommended Dietary Allowance (RDA), which is designed to meet the needs of nearly all healthy people.

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Recommended Daily Allowances (RDA)

Once the Estimated Average Requirement (EAR) has been established, the Recommended Dietary Allowance (RDA) can be calculated. While the EAR meets the needs of 50 percent of a healthy population, the RDA is set to meet the needs of 97–98 percent of people in the same life-stage and sex group. Because of this, the RDA is the preferred intake target for populations and individuals.

It is important to understand that the RDA is not the same as an individual requirement. For example, consuming less than the RDA for calcium does not automatically mean a person is deficient or will develop osteoporosis—an individual’s true requirement may be lower than the RDA. However, because most people do not know their exact nutrient needs, the RDA serves as a practical and protective target. The further intake falls below the RDA, the greater the risk of inadequacy over time.

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Comparing the RDA and the EER

It’s interesting to compare and contrast the EER (for energy or calorie intake) and the RDA (for nutrient intake).

• EER (energy): Designed to meet the average calorie needs of an individual to maintain body weight

• RDA (nutrients): Designed to meet the needs of nearly all healthy people

If the EER were set like the RDA—to meet the needs of almost everyone—it would greatly overestimate calorie needs for most people and lead to weight gain. This approach works for nutrients because the body can store, metabolize, or excrete excess amounts of many nutrients, making modest intakes above requirements generally safe.

Adequate Intake (AI)

When there is not enough scientific evidence to establish an Estimated Average Requirement (EAR) and Recommended Dietary Allowance (RDA) for a nutrient, the National Academies may set an Adequate Intake (AI) instead. The AI is based on observed intakes of healthy people and represents a best estimate of the amount needed to maintain nutritional adequacy. Although less precise than an RDA, the AI serves as the intake goal when no RDA is available.

A common example is infancy, where exact nutrient requirements are difficult to determine. In these cases, AI values are based on observed intakes of healthy infants.

Tolerable Upper Intake Levels (UL)

While consuming too little of a nutrient can lead to deficiency, consuming too much can also cause health problems. The Tolerable Upper Intake Level (UL) is the highest average daily intake of a nutrient unlikely to cause adverse health effects in healthy individuals.

Excessive intakes may occur when using dietary supplements, consuming highly fortified foods (such as protein bars or energy drinks), or relying on a very limited variety of foods. For this reason, supplements should be chosen carefully and should not exceed the UL for any nutrient unless recommended by a physician or registered dietitian.

Not all nutrients have an established UL. When a UL has not been set, it does not mean that high intakes are necessarily safe—only that there is currently insufficient evidence to determine a safe upper limit. Because nutrition science continues to evolve, caution is still warranted with high-dose nutrient intakes.

Comparing the DRI

The graph below summarizes the meaning of the 4 DRI values for nutrient intake.

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At very low intakes, the risk of nutrient deficiency is high. As intake increases, this risk decreases. The EAR meets the needs of about 50 percent of healthy people, while the RDA meets the needs of nearly all (97–98 percent) healthy individuals. When there is insufficient evidence to establish an EAR and RDA, an AI is used as the recommended intake goal. The UL represents the highest average daily intake unlikely to cause adverse health effects. Intakes above the UL may increase the risk of toxicity or other harmful effects.

How DRIs Are Used

You can use the DRIs to assess and plan your diet. Because nutrient needs vary from day to day, DRIs are intended to evaluate average intake over time rather than intake on a single day. In other words, you do not need to meet every DRI recommendation every day; consistently meeting them over several days or weeks is generally sufficient.

DRIs are also used by health professionals, government agencies, researchers, and the food industry to develop nutrition recommendations, plan meals, monitor dietary intake, and create food labeling standards.^[1]

Table 2.9  How the DRI Are Used 

User	How DRIs Are Used
Health professionals	Dietary counseling and menu planning
Government agencies	Dietary Guidelines and MyPlate
Food industry	Nutrition labeling
Assistance programs	School meals, WIC, SNAP
Researchers	Nutrition monitoring
Military	Meal planning and rations

attributions

This section is an adaptation of “Defining Nutrition Requirements” in Nutrition: Science and Everyday Application by Alice Callahan, PhD; Heather Leonard, MEd, RDN; and Tamberly Powell, MS, RDN under a Creative Commons Attribution-NonCommercial 4.0 International License.