Dietary Reference Intakes (DRI): The Ultimate Guide

The dietary reference intakes (DRI) are the standards used in the United States and Canada to assist in nutritional planning; these standards outline recommendations regarding how many calories (energy intake), how many and what kinds of nutrients, and how much water an average person needs to ingest daily.

A committee of nutrition experts — consider it the DRI Committee — establishes the DRI and consists of clinicians and health professionals who use clinical studies in nutrition to provide the goal values for fats, carbohydrates, water, proteins, vitamins, minerals, and energy expenditure. The committee’s recommendations tell you how much of each type of nutrient a person needs daily, based on the amount of energy that person expends, and these values are based on scientific studies.

Four lists of values make up the core of the DRI, which you can read more about in the following sections:

  • Recommended dietary allowances (RDA) and adequate intakes (AI): These guidelines set recommended intake values of nutrients that people should get from their diets. These recommendations satisfy the needs of 97.5 percent of healthy individuals.
  • Estimated average requirements (EAR): These guidelines set nutritional policies at local, state, and federal levels that would satisfy 50 percent of healthy individuals.
  • Estimated energy requirements (EER): These requirements indicate the number of calories you must consume to maintain your current weight.
  • Upper Intake levels (UI): These guidelines determine nutritional safety and indicate the highest amount that can be ingested daily without causing side effects.

The purpose of these lists is to provide accurate guidelines and responsible goals to help individuals achieve optimum health status, to define limits of safety for dietary intake, and prevent chronic disease.

The units used for the dietary reference intake guidelines are International Units (IU) and milligrams (mg). Some nutrients are more commonly expressed as either one or the other. You can find more information on IUs at the following website: how-much-is-an-international-unit/.

The RDA: Setting recommended intake values

The recommended dietary allowance (RDA) is the amount of a nutrient that meets the needs of 97.5 percent of all healthy individuals within a group of people. Why aren’t these recommendations good for 100 percent of the population? Because some individuals may need more or less, depending on their specific medical needs or issues. The general guidelines, for example, aren’t suitable for someone on an elemental diet (a form of strict nutritional therapy).

Here are some things to keep in mind about RDAs:

  • The RDA is the official recommendation the DRI Committee sets for the population. These values are defined after rigorous experiments and are the values that the vast majority of the population should follow to help ensure optimum health.
  • RDAs are the foundational information that Americans can use to guide their nutrient intake. All the other recommendations about what nutrients you should eat and in what amounts stem from the RDAs. These guidelines encourage healthy outcomes by giving individuals the information they need to establish responsible dietary patterns.
  • An established RDA is a generous value, covering almost all individuals in a population with enough of a given nutrient to prevent deficiency diseases. Not everyone needs as much of a nutrient as the RDA specifies, but the human body does a fantastic job at managing the excesses to prevent toxicity issues. 

Looking at how the values are derived: EARs

The RDA values don’t just appear out of nowhere. They are based on rigorous scientific research and experiments that help researchers determine what daily intake level is safe and healthy.

In the quest to establish a specific RDA, the DRI Committee conducts numerous experiments on a nutrient, and the results from each of these preliminary experiments establish an estimated average requirement (EAR) value for that nutrient. An EAR is the average daily intake of a nutrient that meets the nutritional needs of half the individuals in the group.

The EAR value is temporary because the available information isn’t strong or because it isn’t reliable enough to define the actual RDA. Along the way to developing RDAs, a series of adequate intake (AI) values are defined with the assistance of determined EARs; an AI serves as a temporary guideline from which to suggest daily allowances of specific nutrients. Only when scientists feel comfortable with the existing evidence do they formally define RDAs.

Just like the RDA, the EAR is expected to meet or exceed the nutritional needs of almost everyone in the group. However, the EAR is an estimate based on preliminary experiments and is not a defined calculation, as is the RDA. In other words, EARs serve as recommendations until nutrition experts feel comfortable that the level of evidence is strong enough to establish the RDA.

In addition to helping establish the RDA, EARs also provide nutritional guidance to subgroups in a population. Subgroups are clusters of people who, although part of a larger population, are defined by some unique characteristic, usually a demographic identifier, like sex, race, age, or ethnicity. For example, the DRI Committee establishes EARs for different age groups (seniors or teenagers, for example) or racial or ethnic groups (white, black, Asian, or Hispanic). Other EARs are produced for other subgroups.

Estimated energy requirements (EERs): Monitoring your energy intake

You need a certain amount of calories per day to encourage the best possible health outcomes, and the estimated energy requirements (EER) are guidelines that indicate how many calories (energy) an individual should consume. The purpose of EERs is to help individuals not overconsume calories and to dis- courage improper weight gain.

As I noted earlier, RDAs of vitamins and minerals can be generous because your body has a way to remove excess amounts through excretion. Energy intake recommendations, on the other hand, cannot be generous because the body doesn’t have an easy way to get rid of excess calories. In fact, the primary way to remove excess energy is to exercise more — an act that many people loathed to do. For that reason, people have to be careful about how much they consume.

Factors like gender, age, and activity level impact the optimum number of calories a person consumes in a day. To determine how many calories you should eat in a given day, you need to factor in your height, your weight, your age, your activity level, and any medical conditions that you may have. Although the EER is set up for the average man or the average woman, the amount of calories that you need in a given day is specific to you, based on the listed criteria.

The foods you choose need to be primarily nutrient-dense, not energy-dense. In other words, you need to eat more fruits and vegetables (nutrient-dense) and less french fries (energy-dense). The good news, however, is that you can enjoy energy-dense food as part of a healthy diet.

The term discretionary calories refer to the energy you can consume daily in excess of the energy you need for healthy body function. Say, for example, that you need 2,000 calories a day per your EER; approximately 1,700 of those calories should come from nutrient-dense, lower energy-dense foods.

But you have approximately 300 discretionary calories that you can consume from a range of different sources to fulfill your EER. You can choose a soft drink, pizza, celery, whatever. What you choose is up to you. As long as you don’t go above your EER, which would cause you to gain weight, you can get your discretionary calories from any food source you like.

You can find more information on how to determine how many discretionary calories you should consume at the following website, which shows the section on discretionary calories in the USDA’s publication Nutrition and Your Health: Dietary Guidelines for Americans.

For every 3,500 calories you consume in excess of your EER, you put on one pound of body weight. Add it up: A bottle of soda contains approximately 220 calories. If you consume five bottles a week in excess of your EER, you’re consuming an extra 1,100 calories per week. If you continue at that rate, in less than a month, you may put on one pound of body fat just from extra soda consumption alone.

Upper intake levels (ULs): Determining nutritional safety

Upper intake levels (ULs) provide information on the maximum amount of a nutrient you should consume. If you consistently consume an amount of a given nutrient above the UL, the toxicity of that nutrient can result.

Can there be a tolerable lower intake level? Sure. It’s the value that represents the minimum amount of a nutrient you should consume. Consistently consuming an amount of a nutrient below this level can produce a deficiency disease.

Although ULs provide information about how much of a nutrient is safe to consume, keep in mind that gray areas between healthy levels and toxicities or deficiencies exist. In other words, these levels don’t work like switches, in that once you get below or above the safety intake levels, you’ll get sick immediately.

Instead, individual tolerances to lower or higher intakes of a certain nutrient exist and can result in a variety of responses to over or under consumption of a nutrient. If both a child and a healthy adult eat above the recommended level of a certain nutrient, for example, the child’s response would probably be different from the healthy adult’s response because, as a group, children usually are a more vulnerable population.

When trying to understand RDAs and ULs, keep in mind that the response between healthy and unhealthy levels is definite but gradual. You don’t often experience an automatic or immediate adverse response as soon as you cross the threshold. Taking a view that is too simplistic can lead you to erroneously assume that you don’t need to worry about regularly exceeding or going below the ULs. A better view is one that acknowledges a transition zone between safe and dangerous levels.

Although the RDA is generous with nutrient levels, don’t automatically assume you can consume as much as you want without the risk of adverse health outcomes resulting from that overconsumption. You really need to be careful with what and how much you put in your body. To be safe, consult with a physician on any major dietary change.

Acceptable macronutrient distribution ranges (AMDR): Preventing disease

The end goal of all these guidelines and recommendations is to make you healthier. Simple as that. Chronic diseases are now becoming pandemics (worldwide epidemics, or outbreaks of diseases) and the majority of these diseases stem from unhealthy behaviors, like tobacco use, alcohol abuse, unsafe sex, a lack of exercise, or, most pertinent to this book, improper nutrition. To combat this trend, the DRI Committee produces acceptable macronutrient distribution ranges (AMDR).

The purpose of the AMDR values is to help prevent chronic disease by presenting lifelong nutritional goals of energy intake, including guidelines on daily carbohydrate, protein, and fat consumption. According to the AMDR,

  • 45 percent to 65 percent of daily energy should come from carbohydrates
  • 20 percent to 35 percent of daily energy should come from fats
  • 10 percent to 35 percent of daily energy should come from proteins

If you follow the simple dietary guidelines outlined in the AMDR, your risk of becoming obese or developing diabetes, heart disease, and many other diseases linked with improper nutrition is dramatically reduced.

The values set by the DRI Committee are meant for healthy individuals only and are not applicable to people who need very specific dietary regimens. Those with special dietary needs should consult with a physician, who can help them determine what their individual guidelines should be.

Beyond the U.S.: Standards from around the World

A misconception of nutritional guidelines is that the majority stems from an internationally accepted or even U.S.-driven standard. For some nutrients, perhaps this is true, but other nations, particularly other Western nations — Australia, the U.K., Canada, the European Union, and so on — have their own unique approaches to presenting dietary recommendations for health and wellness. In this section, I outline some of these initiatives.

The European Food Safety Authority

In much the same way that the DRI Committee establishes RDAs for Americans and Canadians, the European Food Safety Authority (EFSA) establishes dietary reference values (DRVs) for the European community. The end goal is to produce healthier outcomes for EU citizens by providing scientifically sound research on what is good to eat and in what amount, and by whom it should be eaten.

The EFSA guidelines are similar to the American/Canadian DRI recommendations, with the main differences being the official labels given to the recommendations. For example, the DRI produces RDAs, while the EFSA produces DRVs.

The thing to remember about both RDAs and DRVS (and most other such recommendations) is that they apply to healthy individuals but don’t apply to people who have specific health issues or special dietary needs — an approach that is the standard when making dietary recommendations meant to meet the needs of the majority of a population.

You can find more information on the EFSA at the European Food Safety Authority website: drv.htm.

Australia’s Food for Health

Australia’s Food for Health produced the Dietary Guidelines for Australians to provide tips and recommendations for how Aussies should be eating to promote optimum health outcomes. The guideline offers tips for adults and children on how to prevent unwanted weight gain and how to prepare food properly, as well as other helpful information on how to be healthier by eating and living well.

The UN’s World Health Organization

The World Health Organization (WHO) of the United Nations (UN) has a rich history on publishing guidelines for proper dietary intake. The WHO pro- duces a wide range of information — from special issues on the prevention of chronic disease to actual food-based dietary guidelines — for billions of people.

Because hunger and obesity are worldwide problems, the WHO’s efforts are multinational and comprehensive and include guidelines on the following:

  • Calcium and other supplementation in pregnant women 
  • Recommendations on wheat and corn flour fortifications 
  • Iron supplementation for school-age children
  • Sodium intake for adults and children
  • Protein-energy malnutrition for females and children

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