This is not the first time I’ve written (or spoken) about the problems that plague conventional prenatal nutrition guidelines. Sometimes I feel a bit like a broken record, but judging by the questions that come my way from clients and from colleagues, I clearly need to talk about this more.
In this post, I’ll cover a handful of specific examples of how our conventional nutrition guidelines fall short for pregnant women. I specify a handful because there are many, many, many more issues that need attention—more than can be adequately covered on a blog (hint: you need a whole book to do it justice).
Research is constantly evolving, especially in the field of nutrition, and yet, there’s a lag time between new evidence getting incorporated into public policy. I’ve seen it firsthand. It’s unfortunate, but it’s the reality. No matter how great the program is and how good the people are, it takes an almost insurmountable amount of energy, effort, and most of all, TIME, to shift strongly-held beliefs. (And not to mention, the conflict of interest when corporations that have food-like products or medications to sell see their profits at stake with a change in such policies.)
Often, the battle of getting new information out into practice can take decades. Take, for example, trans fats. Researchers were speaking out against the use of trans fats starting in the 1960’s (if not sooner), and yet trans fats were not required to be labeled on food products (via the nutrition facts label) until 2006! Meanwhile, millions of people who were diligently following doctor’s orders to use margarine instead of “artery-clogging” butter were unknowingly setting the stage for heart disease, diabetes, and cancer.
I’ve been scouring the pregnancy nutrition research for years, particularly in the past year+ (as I was researching for my book, Real Food for Pregnancy) and have discovered a wide gap between current prenatal nutrition policies and the latest evidence-based research.
Here are a few examples.
Why Prenatal Nutrition Guidelines Need to be Updated
If you look at any prenatal vitamin, you’ll see the”% daily value” listed to the right of every vitamin/mineral included in the formula. Most assume that as long as it says 100%, you’re set. You may be surprised to learn that recommended daily allowances (RDAs) are best-guesses and not set in stone. This is especially true for pregnancy, because most RDAs were set using data from adult men and then adjusted via mathematical estimations.
Or to put it this way:
“Nutrient requirements during pregnancy are usually calculated by adding an increment to the value for nonpregnant and nonlactating women that covers the cost of fetal growth and development and the associated changes in maternal tissue metabolism. This factorial approach, however, may not necessarily be correct because it does not take into account metabolic changes in absorption or excretion.” (American Journal of Clinical Nutrition, 2000)
Don’t get me wrong, the RDAs are still a good ballpark goal, but they aren’t perfect. When it comes to vitamin B12, the latest data suggests that pregnant women need TRIPLE the current recommended amount. (Journal of Nutrition, 2015)
This could be a significant concern for women who do not eat foods rich in vitamin B12 and/or rely entirely on a prenatal vitamin to meet their needs for vitamin B12 (such as vegetarians or those who limit foods of animal origin). B12 is one of many nutrients where *actual* needs are now known to be higher than current estimates.
Ever wonder why so many pregnant women crave pickles and olives? It’s probably the salt. Why? Because salt is an essential nutrient. I repeat: salt is an essential nutrient.
When you’re pregnant, your body has more fluids on board (blood volume expands + amniotic fluid) and when you have more fluids, you need more salt to balance it out. Think about it for a minute. If you’ve ever received IV fluids at the hospital, did they give you plain water? NO! They give you salt water because all of your bodily fluids also contain salt, where it serves as an electrolyte (among many other functions).
Many women are told to restrict salt (or they certainly are not told to eat more of it) as a means to avoid fluid retention or high blood pressure, but neither of these suggestions are scientifically sound. A Cochrane review—a highly respected source of evidence-based analyses—concluded that advice to lower salt intake in pregnancy should not be recommended. This advice holds true even for women who have high blood pressure or preeclampsia (some research suggests that more salt, NOT LESS, is ideal in these situations).
In fact, restricting salt can have serious consequences, such as growth restriction in baby and even fetal loss.
As one researcher explains,
“Salt is one of the integral components for normal growth of fetuses. Salt restriction during pregnancy is connected to intrauterine growth restriction or death, low birth weight, organ underdevelopment and dysfunction in adulthood probably through gene-mediated mechanisms.”(Journal of Biomedical Science, 2016)
“Extra salt in the diet seems to be essential for the health of a pregnant woman, her fetus, placental development, and appropriate function.” (Journal of Reproductive Immunology, 2014)
I’ve written about myths about salt in the past (see this article), and pregnancy is no exception. I could go on and on about this, but I cover all the relevant research on this topic in Chapters 2 and 7 of my book, Real Food for Pregnancy. The short answer is that salt is nothing to fear during pregnancy and, perhaps surprisingly, there are legitimate concerns about not getting enough salt.
Choline is still a new kid on the block in the nutrition world. Suggested intakes for choline were not set until 1998. If it had been discovered in the early 1900s, it would have been named something like “vitamin B45.” Originally studied for its role in liver function, choline is now well known to affect methylation, help prevent neural tube defects (alongside folate), and improve brain development.
The recommended intake for choline is higher during pregnancy (and even more so during breastfeeding), but these levels may not be enough. The latest data suggests that choline intakes TWICE that of current recommendations (930 mg vs. 450 mg) during pregnancy is optimal and is linked to higher cognitive function in infants, better placental function, and lesser chances of preeclampsia. (FASEB, 2013; FASEB, 2017)
This is great to know, but not exactly good news for conventional guidelines that suggest women avoid the most valuable source of this nutrient: liver. They also shy away from including the second-best source in sufficient quantities: eggs.
If you read through the Academy of Nutrition and Dietetics’ sample meal plan for pregnancy, the only eggs you’ll find are in the teeny tiny amount of low fat mayonnaise on the sandwich at lunch. Choline is found in a variety of foods other than eggs and liver, but in much lower quantities (we’re talking 115 mg in an egg yolk vs. 30 mg in ½ cup of cauliflower—and cauliflower is lauded as a good vegetarian source of choline as most other veggies have maybe 10 mg per serving, at best). Their meal plan barely squeaks by on choline needs and is nowhere close to the 930 mg that new research suggests in optimal.
Already, fully 94% of women do not meet the daily recommended intake of choline. (Journal of the American College of Nutrition, 2016) If the current guidelines were really up-to-date, they would, at the very least, highly encourage the consumption of eggs. Egg eaters have, on average, double the intake of choline when compared to non-egg eaters. My guess is that old—and unfounded—fears surrounding cholesterol are part of the hold up.
For more on why eggs are such an incredible food for pregnant women, read this.
Conventional prenatal nutrition guidelines reflect government dietary guidelines; you know, the ones that push a high-carb, low-fat diet with 9-11 servings of carbohydrates, “half your grains whole,” and limited amounts of meat. This advice unfortunately does not reflect the last 3+ decades of research.
For one, the nutrients most commonly lacking in prenatal diets (such as choline, vitamin B12, DHA, and iron) are naturally the ones that contain protein and fat. If you’re to try and meet the macronutrient requirements in the current guidelines (45-65% carbohydrates), it’s very hard to “meet your macros” and also obtain enough of these nutrients from food alone.
Second, protein requirements during pregnancy are higher than we previously thought. Conventional nutrition guidelines suggest an estimated average protein requirement of 0.88 g/kg, or about 60 g of protein per day for a 150 lb woman. However, this recommendation is not as evidence-based as we would hope, as it relies primarily on data from nonpregnant adults. In fact, only a single protein requirement study of pregnant women was considered when setting this recommendation. (Institute of Medicine, 2005)
In 2015, the first-ever study to directly estimate protein needs in pregnant women was completed. Actual protein needs were found to be 39% higher in early pregnancy (defined as less than 20 weeks by this study) and 73% higher in late pregnancy (after 31 weeks) when compared to current estimated average requirements. (Journal of Nutrition, 2015)
The take home message from this research is that your body’s demand for protein “increases steadily as pregnancy progresses.”
Third, a high-carbohydrate diet is not the best option for women with higher blood sugar. Given the current state of affairs in the US, 49-52% of adults have either diabetes or prediabetes (most undiagnosed), so suggesting that all women eat a high-carbohydrate diet in pregnancy (i.e. one that raises blood sugar) is not best practice. (JAMA, 2015)
For example, researchers at Stanford University have shown that elevated blood sugar (far below the diagnostic threshold for gestational diabetes) is linked to a significantly higher risk of congenital heart defects. (JAMA Pediatrics, 2015) In a different study, high insulin levels (your body’s response to high blood sugar) in early pregnancy were linked to a significantly higher risk of neural tube defects. (Epidemiology, 2001)
Higher carbohydrate diets may also set women up to gain too much weight during pregnancy and may even have a carryover effect on their children’s propensity for obesity later in life.
For example, higher levels of obesity have been observed among infants and children exposed to this level of carbohydrate intake (52% of calories) in utero, even among healthy weight mothers eating within or below their estimated calorie needs. (American Journal of Clinical Nutrition, 2017)
I’m not saying (and have never said) that women shouldn’t eat any carbohydrates; they just should be half of the diet for most women. At the very least, advice to make “half your grains whole” should be retired. When you look at micronutrient intake among pregnant women, those eating the most high-glycemic carbs have the lowest micronutrient intake. (American Journal of Clinical Nutrition, 2015)
We can do better
If we want to give pregnant women the best chance of having a healthy pregnancy and a healthy baby, we desperately need to get better, more up-to-date, and scientifically sound advice out there.
I had a hard time hitting ”publish” on this blog post because it just scratches the surface of the myriad of reasons why prenatal nutrition guidelines need to be updated.
I’ve spent hundreds of hours reading research paper after research paper piecing together where we went wrong, why, and how we can do better. Thousands of research papers later, more than a year of writing, and a lot of breast milk, sweat, and tears, I’m excited to let you know that I’ve finally finished my second book, Real Food for Pregnancy.
Other areas that are beyond this post, but relevant to this discussion: omega-6 to omega-3 ratio, glycine needs, saturated fat, food safety (do you really have to swear off sushi and runny eggs?), fish vs. mercury debate, liver (does it really risk vitamin A toxicity?), vegetarian/vegan/plant-based diets, artificial sweeteners, alcohol, caffeine, pesticide residues and environmental toxins, advice on supplements, and much, much more.
Real Food for Pregnancy lays out all the evidence—over 930 citations—that supports a nutrient-dense, real food diet during pregnancy for optimal health of both mama and baby. It also delves deeply into all of the above controversial topics, so you can make a truly informed decision about your food and lifestyle choices.
Here’s what a few smarties are saying about it:
“No one has dissected the research on prenatal nutrition—and done so in the context of ancestral diets—to the depth that Lily Nichols has in Real Food for Pregnancy. If you want an evidence-based rebuttal to the outdated prenatal nutrition guidelines, look no further.”
—Robb Wolf, 2x NYT Bestselling Author, Wired to Eat & The Paleo Solution
“Real Food For Pregnancy should find its way into every medical school and prenatal clinic. Lily Nichols’ first book, Real Food for Gestational Diabetes, is a staple in my teaching here at West Virginia University and has shifted how many in our department view nutrition. Her second book is encyclopedic; it’s amazingly well-referenced and more in-depth than many textbooks. If mothers embrace Lily’s advice, the next generation will hopefully suffer less obesity and diabetes.”
—Mark Cucuzzella, MD, FAAFP, Professor at West Virginia University School of Medicine
“As a practicing CNM (midwife) for almost 30 years, I am thrilled to have found Lily’s writing and expertise. Real Food for Pregnancy is one that we’ll keep in stock at our clinic and will teach from during our early pregnancy classes. I really enjoyed the descriptions of the vitamins and minerals and how to get them from food. In my experience, too many people believe that prenatal vitamins will solve all of their problems or will guarantee the health of the baby.”
—Cheryl Heitkamp, APRN, CNM, President of Willow Midwives in Minneapolis, MN
“Real Food for Pregnancy should be considered essential reading for any woman who is currently pregnant or planning conception in the near future. I have not found a similar text with the breadth and depth of discussion on prenatal nutrition. What sets Real Food for Pregnancy apart is how it logically explains the current scientific evidence that is disrupting modern nutrition science and pushing conventional dogma into a new direction. Lily Nichols’ meticulously cited text provides not only a quick read but also plenty of details and references for those who wish to dig further. This book may very well serve as the tipping point leading to a sea change in nutrition science and medical care. I will be recommending it to my patients within my busy high-risk obstetrics practice.”
—Amit Bhavsar, MD, Board certified Obstetrician-Gynecologist practicing outside of Austin, TX
If you’re interested to learn more, Real Food for Pregnancy is available for pre-order on Amazon (PRINT or KINDLE). It’s currently priced 30% lower than retail (and Amazon seems to have dropped the price even more this week, so act quick!). We go to print at the end of February.
Read the first chapter for FREE!
Waiting not your thing? Curious to learn more about the book before buying?
You’re in luck! I’m giving away the first chapter for FREE over at www.realfoodforpregnancy.com.
In this excerpt from the book, you’ll see a side-by-side comparison of the nutrient breakdown from one of my “real food” meal plans and the conventional one. Can you guess which one is more nutrient dense?
If you agree that prenatal nutrition guidelines need to be updated, you’ll definitely want to read this.
Until next week,
PS – Did you catch that?
Real Food for Pregnancy is available for pre-order at a steep discount.
Read the first chapter 100% for free. It’s my gift to you (and the next generation). Get it here.