Vitamins and Minerals for Good Nutrition: What Does Dietary Reference Intake Mean?

Vitamins and Minerals for Good Nutrition: What Does Dietary Reference Intake Mean?

(Last Updated On: September 8, 2019)

Dietary Reference Intake

To understand how much of a macronutrient or micronutrient you need daily you must understand the concept of dietary reference intake. Vitamins and minerals, also known as micronutrients, are the co-factors your body uses to run critical chemical pathways within the human body. Unlike the three macronutrients – protein, carbohydrates, and fat – that you need in substantial quantities for energy and tissue repair, you only need vitamins and minerals in small quantities. However, this doesn’t make them unimportant. In fact, potassium and calcium are needed on a minute-by-minute basis to regulate your heartbeat and for muscles to contract. From a longer-term perspective, deficiencies of certain vitamins and minerals can lead to health problems and even death.

The quantity of each vitamin and mineral that you need each day varies slightly from individual to individual. Some people have higher requirements for one vitamin or mineral because they have health problems, take a medication that depletes one or more micronutrients, or due to lifestyle factors. For example, smokers need around 35 mg. more vitamin C daily relative to non-smokers. People who consume large amounts of alcohol need more B-vitamins since alcohol depletes these vital micronutrients. However, there are certain guidelines in place to give you an idea of how much of each vitamin and mineral you should get each day. You may have seen some of these guidelines and wondered what the different terms mean. Let’s look at each one.

Dietary Reference Intake

Dietary reference intake or DRI is a group of terms established by the Institute of Medicine. These terms, as a whole, are designed to give individuals a better idea of how much of each vitamin and mineral they need each day. Dietary reference intake is broken down into:

·        Recommended Dietary Allowance (RDA)

·        Adequate Intake (AI)

·        Tolerable Upper Intake Level (UL)

Let’s look at each one:

Recommended Dietary Allowance (RDA)

This RDA is the daily amount of a particular vitamin or mineral that meets the needs of 97.5% of the population. It’s the quantity sufficient to meet your body’s needs, as long as you fall within this 97.5% and aren’t currently ill or malnourished. Keep in mind that this amount isn’t necessarily the amount you need for optimal health, it’s the lowest quantity you need to meet your body’s baseline nutritional needs. It’s also the amount your body needs to prevent symptoms of a deficiency. For example, not consuming the RDA for vitamin C over a long period of time can lead to vitamin C deficiency disease called scurvy. RDA is based on a person’s age and gender. For example, children will have an RDA that’s different from an adult or elderly individual and elderly people have a higher RDA for some micronutrients than younger people. Men and women may have differing RDA’s as well. For example, the RDA for iron for men is 8 milligrams while women need 18 milligrams daily. These values can change during pregnancy as well.

Estimated Average Requirement (EAR)

Another nutritional value is the estimated average requirement or EAR. It’s defined as the amount of vitamin or mineral intake required to meet the needs of half the population. In other words, at this level, the risk of being deficient is 50%. Researchers use the estimated average requirement (EAR) to determine the recommended dietary allowance. (RDA) Once you know the EAR, you calculate two standard deviations above and below the EAR and use that as the RDA since two standard deviations cover the needs of 98% of the population.

Adequate Intake (AI)

In the world of nutrition, AI doesn’t mean artificial intelligence. Instead, it refers to adequate intake. Researchers use AI in cases where they can’t establish an estimated average requirement or EAR. AI comes into play when there’s not enough available evidence to determine an EAR. So, they use the results of population studies to determine AI. The values come from large studies such as the National Health and Nutrition Examination Survey.  All in all, an adequate intake is a less reliable measure relative to the RDA and the two values may differ from one another.

Tolerable Upper Intake Level (UL)

Finally, there’s a term called the tolerable upper intake level or UL. This value refers to the highest quantity a healthy person can consume without having a high risk of side effects. Not all vitamins and minerals have a tolerable upper limit or UL since some micronutrients, like B vitamins, don’t have immediate risks even when you take large supplemental doses. Since B vitamins are water soluble, the excess is flushed out or your body, making it unlikely you’ll experience adverse reactions.

Dietary Reference Intakes Aren’t Set in Stone

The values for RDA, EAR, and AI may change over time as new information comes out. As with most things in the nutritional world, they aren’t set in stone. For example, the Institute of Medicine revised the recommendations for vitamin D after it became apparent that adults and children needed more vitamin D to avoid deficiency.

How Can You Use This Information?

When you look at a nutritional label, the label will usually give you the daily value (DV) for a particular vitamin or mineral followed by a percentage value. The DV refers to how much of a particular nutrient or micronutrient a single serving of that food contains. For example, the DV for calcium is 1,000 milligrams. If a serving of a packaged product contains 300 milligrams of calcium, the percentage value listed will be 30% since a serving supplies 30% of the DV. Track these values based on what you eat and see if they add up to 100%, meaning you met the daily value. Then, compare it to the RDA based on your gender and age to see if you’re consuming the right amount.

The Problem with Dietary Reference Intakes

The values for dietary reference intake, including the RDA, are designed to tell you how much of a particular micronutrient you need to avoid a deficiency. For example, if you consume the RDA for vitamin C, you won’t develop scurvy. But consuming the RDA doesn’t necessarily mean you’re getting enough of that micronutrient for optimal health. That’s why it’s important to eat a nutrient-dense diet that contains a diversity of whole foods, rather than focusing on only meeting the RDA. What you eat really does matter for your health now and in the future. So, make sure you’re making smart choices!

 

References:

National Institutes of Health. “Nutrient Recommendations: Dietary Reference Intakes (DRI)”

Medscape.com. “Updated Vitamin D and Calcium Recommendations”

 

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