The Limitations of the RDAs

Have you ever thought that understanding nutrition can be a little overwhelming? There’s so much information out there, and oftentimes, what you read or hear one place is contradicted with something you read or hear another place.

One resource you might have turned to for advice is the Recommended Dietary Allowances, or RDAs, as established by the Food and Nutrition Board of the Institute of Medicine, National Academy of Sciences. But it turns out, even these “official” guidelines have some limitations.

About the RDAs

The Recommended Dietary Allowance (RDA) is the average amount of a nutrient a healthy person should get each day. RDAs vary by age, gender, and whether a woman is pregnant or breastfeeding.

When you look at a food label, you won’t see a reference to the RDA for each nutrient, but you will see a reference to the Daily Value (DV), which is the percentage of a nutrient a serving of the food or supplement provides in the context of your total daily dietary needs, using the RDA as a guide.

Why the Recommended Dietary Allowance May Not Be Reliable

While RDAs can be a good guide, there are a number of reasons they may not be the best yard stick. Here’s why:

The Amounts are Intended to Prevent Disease, Not Promote Optimal Health

To understand this point, it’s helpful to understand how and why the RDAs were established. The body that developed the RDAs, the Food and Nutrition Board (FNB), was established in 1940 during WWII to advise the Army on guidelines for good nutrition. The FNB realized the need to develop recommendations for nutritional intake for both the general public and the armed forces and introduced the RDAs the following year in 1941.

The goal of the FNB was to estimate the amount of a nutrient necessary per day for the maintenance of “good health.” The term “good health,” as it relates to the RDAs, refers to the minimum nutritional amounts necessary to avoid disease conditions, such as scurvy, a condition caused by too little vitamin C, or rickets, caused by too little vitamin D.

However, in many cases, these minimum amounts are far lower than optimal amounts that are fully supportive of good health. There is a big difference between the amount of vitamin C needed to prevent scurvy and the amount needed for an optimally functioning immune system. 

It’s worth noting that the FNB does revise the RDAs every five to ten years based on advances in research and scientific understanding. For example, they added an RDA for choline in 1998. However, many believe that they still have not kept pace with current research on optimal levels vs. minimum requirements.

The Amounts Group All Adults Into the Same Recommendations

While the RDAs do account for age group and gender, they were originally set using data from adult men in the 1940s and then simply adjusted by general estimates for age, sex, and pregnancy or breastfeeding status. The RDAs also don’t account for many other variables that exist within these groups, like activity level and other medical conditions.

The Recommendations Don’t Consider the Interaction of Other Nutrients

Many nutrients either require another nutrient to fully absorb or can have their absorption blocked by another nutrient. For example, your body cannot properly absorb vitamin D without vitamin K. In addition, when you consume or supplement with iron, it can block the absorption of nutrients like calcium and zinc.

Not Every Nutrient Needed for Optimal Support Has a Recommended Dietary Allowance

Even with a number of RDAs, there are still essential nutrients that the body needs that do not have an RDA. This is generally the case with nutrients that are bioavailable and have a similar but less usable counterpart. An example is that there is an RDA for vitamin K1, but not for the other very important form vitamin K2.  In addition, the FNB does not have an RDA for omega-3 fatty acids DHA and EPA despite tremendous research on their importance on cognitive health at all stages of life.

So What Can You Do Instead?

Use These Numbers as a Guide not Gospel

These numbers are a good guide to start, but don’t put all your trust into them. Scanning a food or supplement’s label and seeing that 100% of the Daily Value for a nutrient is provided can give you false comfort, as it may be less than what you actually need. Similarly, seeing a larger percentage in the DV column might make you wary that you’re getting far too much, when it is actually an optimal amount.

Note Gaps in Your Diet

If you avoid an entire food group or class of foods, chances are good that you’re missing out on some nutrients. These are areas in which you might consider a supplement to fill gaps. For example, if you don’t eat meat, you are more likely to be deficient in nutrients found primarily (or primarily in their active forms) in animal products, like iron and B vitamins.

Note this can be seasonal too – if you tend to eat seasonally and live in a colder climate, you may not have access to foods like fresh antioxidant rich berries and fresh produce year-round, so a supplement like Berry Power or Pure Synergy Superfood could be a good addition to your routine. Of course, a good multivitamin and mineral formula is generally recommended for most of us.

Get Nutrient Testing

If accessible to you, consider nutrient testing to determine exactly where you are deficient so that you can target those nutrients in your diet and supplement routine.

Nutrition Isn’t One Size Fits All

Ultimately, health and nutrition isn’t one size fits all, and so there simply isn’t a set of guidelines that work for every individual. Instead, use the RDAs as a guide, listen to your body, and discuss your specific needs with your individual medical, functional, or naturopathic doctor, or with a dietician or nutritionist.

3 Years ago