5 Areas Conventional Prenatal Nutrition Guidelines Are Wrong – Lily Nichols, RDN

While conventional prenatal nutrition guidelines mean well, unfortunately, there is a lag between newly published nutrition research and public policy updates. And I don’t mean a lag of just a few years – sometimes discrepancies can last for decades! Nutrition advice from the past continues to influence prenatal nutrition education, despite new research that both contradicts and expands on what we know. I read hundreds of studies every year to stay informed on the latest evidence for prenatal nutrition. While there are many recommendations that could be improved, here are five areas where prenatal nutrition guidelines need an update.

Protein

The latest research is suggesting that pregnant women need much more protein than we

previously thought.

The current conventional recommendations suggest that approximately 60 grams of protein per day is adequate for a 150 lb pregnant woman. Unfortunately, this recommendation is based mostly on protein requirement studies from nonpregnant adults.

The first-ever study to directly estimate protein needs in pregnant women was completed in  2015 and found protein needs to be 39% higher in early pregnancy and 73% higher in late pregnancy when compared to current estimated average requirements. This makes optimal protein intake for a 150 lb pregnant woman closer to 80 grams in early pregnancy and over 100 grams in later pregnancy.

That’s a stark increase from the current recommendations! Given all of the demands placed on the body while growing a new human, it makes sense that we likely need much more protein than what is currently advised.

Carbohydrates

While we may need more protein during pregnancy, it’s debatable how much carbohydrate needs increase.

Much like the population-wide dietary guidelines, the recommendations for pregnancy suggest that approximately half of a pregnant woman’s diet comes from carbohydrates (45-65% of calories, to be exact).

However, when we examine the most commonly lacking vitamins and minerals among women of childbearing age, these are often NOT the nutrients found in abundance in carbohydrate-rich foods. Furthermore, the majority of carbohydrates consumed in the United States are from ultra-processed foods, such as products made with white flour or refined sugar. Rather than providing key nutrients, these foods end up displacing other healthy foods from the diet. In fact, research on micronutrient intake among pregnant women has found that those eating the most high- glycemic carbs (the most refined/processed) have the lowest micronutrient intake.

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In the US, 49-52% of adults have either diabetes or prediabetes (most undiagnosed). Because carbohydrates are the only macronutrient that significantly raises blood sugar levels, a high- carbohydrate diet is not the best option for women with blood sugar issues.

Perhaps instead of pushing a high-carbohydrate diet, we should put more emphasis on improving the quality of carbohydrates consumed and individualizing carbohydrate needs to each person. If nothing else, advice to make “half your grains whole” should be revised, and ultra-processed, highly-refined carbs should be discouraged.

B12

Speaking of micronutrients, I want to call out an elephant in the room: our dietary reference values for micronutrients are not as evidence-based as you’d think.

A 2021 review analyzed the 704 studies used in setting the dietary reference intakes for pregnancy. Of all the studies included, only 17% included a single pregnant or lactating participant. For 16 of 23 micronutrients, the reports did not consider any study including pregnant or lactating women.

One nutrient that is particularly in need of a revised recommendation is vitamin B12. The latest research suggests that pregnant women need TRIPLE the current recommended amount.

Foods of animal origin have the highest concentrations of B12. For women who do not eat enough of these foods, or for women who rely entirely on a prenatal vitamin to meet their needs for vitamin B12 (such as vegetarians or vegans), this could be cause for concern. Vitamin B12 is critical for red blood cell production, fetal brain development, organ formation, and many other functions.

Choline

It is well-known that a woman’s need for folate increases during pregnancy, but what is less well-known is the importance of choline, too. Choline is now understood to affect methylation, help prevent neural tube defects (like folate), and improve brain development. Compared to nonpregnant adults, the recommended intake in the conventional prenatal nutrition guidelines is higher during pregnancy and even higher during breastfeeding. However, the latest data suggest that even more choline than what is currently recommended may be necessary.

Recent studies show that choline intake TWICE that of current recommendations (930 mg vs. 450 mg) during pregnancy is linked to higher cognitive function in children from infancy all the way into early childhood. This information is really helpful, but it conflicts with the conventional guidelines that suggest we limit our intake of cholesterol; that’s because the richest dietary sources of choline — liver and eggs — are also some of the highest in cholesterol.

Salt

We’ve all probably known (or been) the pregnant woman craving pickles and olives. Why? It’s probably the salt.

Yes, salt is an essential nutrient. You read that correctly.

During pregnancy, your bodily fluids increase via amniotic fluid and increased blood volume. All of your bodily fluids contain salt because salt serves as an electrolyte. So, when you have more fluids on board, you need more salt to balance this fluid.

Many women during pregnancy are told to restrict salt to avoid high blood pressure or fluid retention. But, a Cochrane review found no evidence that these recommendations are scientifically sound and concluded that lower salt intake in pregnancy should not be recommended. In fact, excessive restriction of salt intake may even worsen high blood pressure or preeclampsia symptoms. This is such a controversial discussion that I devote a lengthy discussion to this elsewhere in my work.

Instead of limiting salt, I recommend my clients consume salt to taste. While it’s true that processed foods can be excessively high in sodium (and I certainly don’t recommend eating too many of those foods due to their lack of essential nutrients), whole foods such as vegetables, proteins, and legumes should be seasoned to taste.

Nourish yourself well: Real Food for Pregnancy

It’s clear conventional prenatal nutrition guidelines haven’t caught up to the findings from the latest research on pregnancy nutrition. This outdated guidance promotes a diet that might result in nutrient deficiencies rather than promoting a nutrient-dense diet that supports the extra demands placed on the body during pregnancy.

REFERENCES:

1. Institute of Medicine Food and Nutrition Board. Dietary reference intakes: energy,

carbohydrates, fiber, fat, fatty acids, cholesterol, protein, and amino acids. Washington,

DC: The National Academy Press; 2005.

2. Stephens, Trina V., et al. “Protein requirements of healthy pregnant women during early

and late gestation are higher than current recommendations.”; The Journal of Nutrition

145.1 (2015): 73-78.

3. Goletzke, Janina, et al. “;Dietary micronutrient intake during pregnancy is a function of

carbohydrate quality.”; The American Journal of Clinical Nutrition 102.3 (2015): 626-632.

4. Menke, Andy, et al. “Prevalence of and trends in diabetes among adults in the United

States, 1988-2012.” JAMA 314.10 (2015): 1021-1029.

5. Smith, Emily R., et al. “Limited data exist to inform our basic understanding of

micronutrient requirements in pregnancy.”; Science advances 7.43 (2021): eabj8016.

6. Bae, Sajin, et al. “Vitamin B-12 status differs among pregnant, lactating, and control

women with equivalent nutrient intakes.”; The Journal of Nutrition 145.7 (2015): 1507-

1514.

7. Bahnfleth, Charlotte, et al. “Prenatal choline supplementation improves child color-

location memory task performance at 7 y of age (FS05-01-19).” Current developments in

nutrition 3.Supplement_1 (2019): nzz048-FS05.

8. Caudill, Marie A., et al. “Maternal choline supplementation during the third trimester of

pregnancy improves infant information processing speed: A randomized, double‐blind,

controlled feeding study.” The FASEB Journal 32.4 (2018): 2172-2180.

9. Duley, L., and D. Henderson-Smart. “Reduced salt intake compared to normal dietary

salt, or high intake, in pregnancy.” The Cochrane database of systematic reviews 2

(2000): CD001687.

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Lily Nichols is a Registered Dietitian/Nutritionist, Certified Diabetes Educator, researcher, and author with a passion for evidence-based prenatal nutrition. Her work is known for being research-focused, thorough, and critical of outdated dietary guidelines. She is co-founder of the Women’s Health Nutrition Academy and the author of two books, Real Food for Pregnancy and Real Food for Gestational Diabetes. Lily’s bestselling books have helped tens of thousands of mamas (and babies!), are used in university-level maternal nutrition and midwifery courses, and have even influenced prenatal nutrition policy internationally. This article includes excerpts from Real Food for Pregnancy. She writes at https://lilynicholsrdn.com/