Understanding Dietary Reference Intakes

Dietary Reference Intakes, or DRIs for short, are a series of values that define the recommended daily requirements, the minimum daily needs, and the maximum tolerable daily amounts for each nutrient. They were developed by the Institute of Medicine of the National Academies in the mid-1990s. (Today, it's known as the Health and Medicine Division of the National Academies of Sciences, Engineering, and Medicine.) Canada and the UK have similar dietary reference values.

There are DRIs for vitamins, minerals, fat, protein, fiber, carbohydrates and even water intake. (They're available on the Health and Medicine Division's website or on this interactive web page) The DRIs are really helpful for dietitians who plan diets because these values help them design well-balanced meal plans so that consumers and clients will be most likely to get all the nutrients they need every day. 

The DRIs are based on age and sex. Not every nutrient is the same, though. For example, the DRIs for iron need vary considerably by age and sex while the DRI for selenium is about the same for all teens and adults. Also, DRIs have been calculated for women who are pregnant or breastfeeding because they usually require a bit more of most nutrients.

The Values That Make up the DRIs

There are five reference values for each DRI.

Estimated Average Requirement (EAR)

The EAR is the average daily nutrient intake estimated to meet the requirement of half the healthy individuals who are all the same sex and of a similar age. It's mostly used by dietitians when they need to plan diets for large groups and by nutrition researchers. It's not something the average consumer needs to worry about.

Recommended Dietary Allowance (RDA)

The RDA is the average daily dietary intake levels that are enough to meet the nutritional needs of about 98 percent of people of the same sex and similar age. This is when knowing the EAR comes in handy because the RDA is calculated from the EAR of any given nutrient. 

The key thing with an RDA is knowing that as long as you meet your RDA for any given nutrient every day, then it's extremely unlikely that you'll be deficient in that nutrient.

So for example, for women, the RDA for vitamin C is 75 milligrams per day. So as long as you eat enough vitamin-C containing foods to meet that mark, you should have plenty of vitamin C. To do that you'll need to eat some fruits and veggies every day. 

Adequate Intake (AI)

The AI is similar to the RDA but not as exact because nutrition scientists haven't been able to establish an EAR and RDA. But even though it's not exact, the AI is still based on good science so it's a great estimate that can be used for planning meals. 

For example, the AI for potassium is set at 3400mg for men and 2600mg for women ages 19-50 (although this number does not apply to those with impaired potassium excretion). The AI is a great mark to shoot for when you're planning your meals. And just like vitamin C, if you eat plenty of fruits and vegetables, you should be able to meet this AI without too much problem.

Tolerable Upper Intake Level (UL)

The UL is the highest level of daily intake of a given nutrient that won't pose a risk to your health in anyone of a similar age and same sex. The UL is most important for supplement use. It's not common to overdo any one nutrient simply by eating foods. But several nutrients can become dangerous if they're ingested in large enough amounts over time. If you are taking dietary supplements, make sure to discuss your intake with a registered dietitian or your physician to assure you are not taking excessive amounts that could be harmful to your health. Too much of certain nutrients can become problematic.

An example of an important UL is for vitamin A. Daily consumption of more than 3,000 micrograms per day may result in vitamin A toxicity and liver problems. And women who are pregnant and take too much vitamin A on a daily basis have a greater risk of certain birth defects.

Chronic Disease Risk Reduction Intake (CDRR)

This category was added more recently to overcome limitations related to nutrient intakes and chronic disease risk. According to the National Institutes of Health, it does not replace the existing DRI categories, but changes how evidence on chronic disease risk is assessed and used in the DRI process. In short, nutrient intakes are suggested that are expected to reduce the risk of developing chronic disease. Sodium and potassium were the first two nutrients reviewed under the expanded DRI model.

How Do I Use This Information?

Your dietitian knows exactly what to do with DRIs, of course, but they're also helpful for the average consumer who's just trying to figure out which foods to eat every day. By reviewing the DRIs and keeping track the nutritional value of the foods you consume, you'll know if you're getting enough of all the essential nutrients.

Before the internet became a daily part of our lives, this was a hassle. But today with sites such as calorie counters and MyPlate, all you need to do is set up a profile, type in the foods you eat (or plan to eat) every day and the site will do the work for you. 

How DRIs Compare to DVs

The Daily Value (DV) was designed by the United States Food and Drug Administration to help consumers learn more about the nutrients found in the packaged foods they're buying. The DV is similar to the RDA or AI, but not always the same because it doesn't take age or sex into consideration. Instead, the DVs are based on daily caloric intakes, and when you look at Nutrient Facts labels, you'll see the DV as "%DV" and you'll be able to see what percentage of your daily need for that nutrient is met by one serving of the food product.

Nutrition Facts labels are required for all packaged foods, but not all nutrients will be listed. You will see things like calories, fats, cholesterol, trans fat, sugars, protein, carbohydrates, fiber, calcium, iron, sodium, vitamin A, and vitamin C. Sometimes you'll see more vitamins or minerals listed, but that's up to the food manufacturer.