Changemaking The Science of Nutrition

Why Pregnancy Dietary Allowances Aren’t Enough

Hillary Bennetts

Why Pregnancy Dietary Allowances Aren’t Enough

Table of contents

  • Intro
  • What Are the RDAs?
  • How Is % Daily Value Different From an RDA?
  • Why Is Meeting an RDA Often Insufficient?
  • Where Can I Find a Better Prenatal

0 min read


Getting the right amount of a nutrient is important. Getting too little (or in some cases too much) of a nutrient can be detrimental. 

In general, prenatal supplements are designed around the Recommended Dietary Allowances (RDAs) for pregnant and nursing mothers. In our view, RDAs are often insufficient, leaving mama and baby without enough of the nutrients they truly need. 

This article will explain what RDAs are, where to find them, why they are often not enough, and what other sources of information we turn to in setting dosages beyond just the RDAs.

What are the RDAs?

The RDAs are the estimated amount of a nutrient (or calories) per day considered necessary for the maintenance of “good health” by the Food and Nutrition Board (FNB) at the Institute of Medicine of the National Academies. The RDAs vary by age, sex, and whether a woman is pregnant or nursing, as nutritional needs are elevated during this life stage. For this reason, many nutrients have multiple RDAs. 

The 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 the general public as well as the armed forces and introduced the RDAs a year later in 1941. 

The FNB has subsequently revised the RDAs every five to ten years based on advances in research and scientific understanding. For example, the RDA for Choline, one of our favorite nutrients, was added in 1998. The most recent RDA revision was in 2016. In our minds, additional revisions are still needed as there is room for improvement with existing RDAs as described below and not every important nutrient has an RDA like the Omega-3s DHA and EPA. There is currently just an RDA for the Omega-3 ALA, but we know the conversion into DHA and EPA is highly inefficient and you really need DHA and EPA separate from ALA.

I generally see a % Daily Value on the Supplements Facts Panel of my supplement. How is that different from an RDA? 

Daily Values (DVs) are established by the U.S. Food and Drug Administration (FDA). DVs suggest how much of a nutrient a serving of the supplement provides in the context of your total daily dietary needs. The FDA sets a DV for pregnancy and nursing women that closely follows the RDA for that life stage. But, because RDAs are often too low, scanning the 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 way less than what you actually need.  

Why is meeting an RDA often insufficient for optimally nourishing a mama or mama-to-be?

There are six main reasons:

  1. RDAs were originally set using data from adult men (dating all the way back to the Army in WWII), adjusted via estimation for age, sex, and pregnancy and nursing needs. These estimates do not account for the myriad differences between the physiology of a man versus a pregnant or breastfeeding woman. And, subsequent revisions are lacking data from research on women. In general, there is a significant lack of research on women’s health. Read more about the gender health research gap here
  2. “Good health,” in the case of defining the RDAs, is anchored on the minimum nutritional amounts necessary to avoid disease conditions, such as spina bifida (a birth defect arising from inadequate Vitamin B9 (Folate)), or the onset of clear symptoms of deficiency. These minimum nutritional amounts are far lower than amounts that are fully supportive or optimal. (Think original war-time heritage.) For example, 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. 
  3. RDAs imply a perfect condition and do not take into account the increased need for certain nutritional elements to combat stress, environmental toxins, illness, poor or adjusted diets, morning sickness, medications, or gut problems that cause malabsorption, all of which can heighten nutritional needs. 
  4. RDAs don’t always account for differences between nutrient forms and how those forms are absorbed and used by the body. For example, the mineral Magnesium can be found as Magnesium Glycinate or Magnesium Citrate, along with nearly a dozen other forms. We choose Magnesium Glycinate because the body is able to absorb and utilize it better than the other magnesium forms. On the other hand, Magnesium Citrate is often used as a laxative because it is so poorly absorbed. The RDA, however, does not account for this difference in absorption between the two forms as it is written for “Magnesium” in general.
  5. RDAs don’t account for the ways nutrients interact with one another. For example, your body cannot properly absorb Vitamin D without Vitamin K. 
  6. Not every nutrient needed for optimal support has an RDA. This is most common for nutrients that are bioavailable and ready to be used by the body like DHA and EPA mentioned above. The FNB has generally not thought of them as essential in their own right versus their less usable counterpart. Vitamin K is another example. There is an RDA for Vitamin K1, but not for the other very important form Vitamin K2.  

    What information other than just the RDA do you incorporate in setting dosages? 

    At Needed, we select nutrient forms and dosages to fully nourish both mama and baby. In doing so, we think it’s important also to consider:

    1. Nutritional amounts available in food (i.e., what you are likely to get outside of a supplement)
    2. Relevant peer-reviewed, published research 
    3. The clinical practice of health practitioners who regularly test the nutrient levels of mamas and mamas-to-be
    4. The physiological mechanisms of nutrient usage, meaning how a particular nutrient form is actually used and stored by the body
    5. Traditional healing practices used across cultures for thousands of years 

    Okay, I get it. I need a better Prenatal. Where can I find the optimal one for me?

    When we were looking for a high-quality prenatal, we researched hundreds of products and could not find one that fully met our needs

    So, we spent 3 years designing one from the ground up that optimally nourishes mamas, going well beyond meeting bare minimum requirements.

    Try our Prenatal Multi Powder, Capsules, or Essentials!

    Like the article? Share it!

    Hillary Bennetts, Nutritionist

    Hillary Bennetts is a nutritionist and business consultant focusing on prenatal and postpartum health. In addition to nutrition consulting, she provides business consulting and content creation for companies in the health and wellness industry. Hillary spent almost a decade in corporate consulting before shifting gears to combine her lifelong passion for health and wellness with her business background and nutrition education.