The field of nutrition is full of controversy. I’m no stranger to it. It’s actually one of the reasons I love my profession so much. Nutrition is complex, science is ever-evolving, and there are so many dots to connect.
Compared to a lot of fields, nutrition is unique in that everybody has to eat, so everybody has a personal experience with it. (Not so much the case if you’re an electrician, a contract lawyer, a pilot, or a surgeon.) Also, since everybody has to eat, food and nutritional supplements are a massive, massive industry. Everything from food companies to higher education to Netflix documentaries have something to sell you (or an ideology to convince you to adopt).
The downside is that truly evidence-based information is hard to come by. Even as a free-thinking registered dietitian with a strong background in research, I have to work really really hard to find unbiased information.
My specialty—prenatal nutrition—is even more challenging because not many types of studies are considered ethical to perform on pregnant women in case it causes harm to the baby. That means many of our current prenatal nutrient recommendations are actually best guesses.
For example, it’s recently been found that the recommended intake for vitamin B12 during pregnancy was underestimated considerably (actual needs are 3x higher). (Journal of Nutrition, 2015) In addition, the optimal intake for choline is likely set far too low. Studies that have supplemented women with more than DOUBLE the current recommendation show significantly better brain development (as measured by reaction time) in infants. (FASEB, 2017)
Why are these two examples relevant to a discussion about a vegetarian diet in pregnancy? Because both vitamin B12 and choline are found primarily in animal foods. If our estimates of these nutrients are off, maybe the recommendation that a diet devoid of animal foods is nutritionally adequate for pregnancy needs to be re-examined.
If you are familiar with my work already, you know my recommendations on optimal nutrition for pregnancy are much, much different than conventional guidelines (which is one of many reasons that I cite and cite and cite my work with relevant research).
When you reverse engineer a nutrient-dense prenatal diet to cover all/most of your nutritional needs from food alone, it’s not a vegan (or even vegetarian) diet. This is surprising, outrageous, and in some cases, angering to many people.
Food choices are a loaded topic
As a former vegetarian myself and friend to many currently practicing vegetarians and vegans, I understand all arguments for and against the consumption of animals.
Let me be 100% clear: I respect your choice.
In the context of pregnancy, when your growing baby is reliant upon your nutrient intake and nutrient stores to grow, there are some important considerations relevant to this choice. This is why I included a very detailed, evidence-based discussion on the challenges of a vegetarian diet during pregnancy in Real Food for Pregnancy.
My job is to look at the data and show you which nutrients could be missing/lacking, how you can make up for them (with food or supplement choices), and some of the downstream consequences of whatever choice you make.
Vegetarian Diet in Pregnancy: Nutrients of Concern
The following nutrients are challenging to obtain from a vegetarian diet:
- Vitamin B12
- Preformed vitamin A (retinol)
- Vitamin K2
If you follow a strictly vegan diet, meaning you consume absolutely no animal foods—no meat, poultry, fish, dairy, or eggs—some of these nutrients may be impossible to obtain from your diet.
What I find worrying about sources promoting a vegan diet as appropriate for pregnancy is that many of the above nutrients are not even taken into consideration.
We have several considerations for the above nutrients on a vegetarian diet:
- Certain nutrients may be missing entirely (such as vitamin B12)
- Certain nutrients may not be provided in sufficient concentrations in plant foods (such as choline, glycine, and vitamin K2)
- Certain nutrients may not be well-absorbed (such as iron and zinc)
- Certain nutrients may be provided in a form that is not as well-utilized by the body (such as the omega-3 ALA instead of DHA and beta-carotene instead of preformed vitamin A)
I know that many people will argue that these nutrients can all be made up for through supplementation, but given that many of the above are not found in prenatal vitamins, that supplements usually don’t contain the same ratios of these nutrients as are found in food (or the same forms of nutrients found in food), and that research is still uncovering valuable nutrients in real foods, I’m not comfortable to say that supplementing a vegetarian diet in pregnancy will 100% cover your nutrient needs.
Let me give you a few examples.
Glycine is an amino acid that becomes “conditionally essential” during pregnancy (meaning you must consume it from food rather than rely on your body making it from other amino acids). Glycine is required to support the growth of your baby’s skeleton, teeth, internal organs, hair, skin, and nails. Plus, it is necessary to support your own stretching skin, growing uterus, placenta, and to help your circulatory system adapt to the demands of pregnancy (some research suggests it plays a role in the prevention of preeclampsia). Glycine also plays a key role in methylation, much like folate, choline, and vitamin B12. In other words, it’s involved in important processes, like the formation of your baby’s DNA and in brain development.
I’ve examined the top 1,000 food sources of glycine and it is found in greatest concentrations in animal foods (mostly bone, skin, and connective tissues, such as you would find in bone broth, slow cooked meat, and poultry consumed with the skin-on). I’m not sure it’s possible to obtain enough glycine on a vegetarian diet during pregnancy, as demands are so high (this is true even for those who consume eggs and dairy, as these are both poor sources of glycine). Studies have shown that non-pregnant vegetarians frequently have urine markers of glycine deficiency. (Journal of Biosciences, 2009)
Worryingly, conventional prenatal nutrition guidelines don’t even mention glycine. I was not taught about glycine with regards to pregnancy during my training as a registered dietitian. And, many nutrient databases don’t make it easy to find the glycine levels in foods. This is an incredible oversight of our current guidelines and something that leaves pregnant women who follow a plant-based diet at risk for glycine deficiency, especially if it’s not on their radar.
Choline is a B vitamin-like compound, which is now known to be absolutely essential to prevent neural tube defects and support brain development. The first recommended intake level for choline was set in 1998, relatively recently compared to other nutrients. (<– See what I’m saying about prenatal nutrition being an ever-evolving field?!)
Even then, the recommended intake was set based on data for adult men and in an amount that was protective of liver damage. This means we really don’t know for sure whether or not the recommended intake is optimal for pregnant women. As alluded to earlier, research in the 20 years since this recommendation was made has suggested that pregnant women need DOUBLE the amount to ensure their babies’ brains develop properly. This is really, really, really important because already 94% of women don’t even meet the current recommendation of 450 mg per day. (Journal of the American College of Nutrition, 2016)
And, the only way they could realistically meet the higher recommendation is through consumption of more animal foods or a choline supplement (most prenatal vitamins don’t contain choline, just FYI).
Eggs and liver are, by far, the most concentrated sources of choline (115 mg per yolk or ounce of liver). Plant sources have, at best, around 30 mg per several ounces – ½ cup of cooked pinto beans, Brussels sprouts, or broccoli provides ~30 mg. To put it another way, you’d have to eat more than 3.75 cups of broccoli to equal the choline contained in a single egg yolk. When I’ve run nutrient analyses on vegetarian vs. omnivorous diets, choline often comes up low (unless, of course, the diet has LOTS of eggs with the yolks).
It’s also probably no mistake that animal sources of choline also come with the omega-3 fat, DHA. Researchers have shown that choline enhances DHA uptake in cells; this is probably pretty important for brain development in and of itself.
Could this explain why many traditional cultures emphasized certain choline-rich foods prior to and during pregnancy? It’s certainly possible.
I’m glad that choline is on the radar of more health professionals these days, but it is unfortunately missing from many outdated sources of prenatal nutrition information, especially those that push a vegetarian diet in pregnancy. For example, the Physician’s Committee for Responsible Medicine’s article on vegetarian diets during pregnancy doesn’t include choline in a list of nutrients of concern (it also fails to include information on glycine, gives incorrect information on DHA, and gives outdated advice on protein & vitamin B12 needs, among many, many other oversights). I’m not going to link out to this article and perpetuate misinformation, but you’re welcome to look it up and see for yourself.
Vitamin A helps regulate gene expression and fetal growth with specific roles in the development of the heart, eyes, ears, limbs, and immune system. Lack of vitamin A can lead to serious malformations, including improperly formed craniofacial structures, limbs, and internal organs.
Most of us have been taught that plant foods are a good source of vitamin A, but it’s important to recognize that plants don’t contain true preformed vitamin A (retinol); rather, they contain provitamin A (carotenoids). This means your body must convert carotenoids into retinol, however, this conversion rate is quite low in many individuals. The most commonly discussed carotenoid, beta carotene, is up to 28 times less potent than retinol (meaning approximately 3% gets converted into retinol in your body, though the conversion rate can be even poorer depending on your genetics). (American Journal of Clinical Nutrition, 2010) You might think you can just eat a lot of sweet potatoes and carrots to flood your system with provitamin A, but that’s unlikely to help. The more beta-carotene you eat, the less you convert to vitamin A. (Journal of Nutrition, 2010)
The only source of dietary retinol is animal fats, so if a woman consumes no animal fat, it’s pretty likely she’ll end up deficient in vitamin A. In a large study from the Netherlands, it was found that women who ate liver—a rich source of retinol—almost always consumed adequate vitamin A, while an astonishing 70% of women who avoided liver failed to meet the RDA. (European Journal of Obstetrics & Gynecology and Reproductive Biology, 1996) This study is important, because it highlights a huge oversight in conventional prenatal nutrition policy. It’s generally assumed that vitamin A deficiency is something that is only common in developing countries with limited access to food, but this study is from one of the wealthiest countries in the world. In this case, it’s not a matter of access to (nor the affordability of) nutritious foods, it’s that women are being actively steered away from them (or are not being told of their nutritional importance).
Simply put, you need to eat preformed vitamin A from either animal sources, such as full-fat dairy or eggs or meat/fish (in other words, animal fats), or supplement to ensure you get enough. Women who eat a vegan diet would not obtain any preformed vitamin A unless they supplement. At the same time, supplements of preformed vitamin A can be risky if taken in large quantities (increase the risk of certain birth defects), but this is not observed with the vitamin A consumed from animal foods.
More Information on the Nutrients of Concern on a Vegetarian Diet in Pregnancy
I’ve received a lot of requests for more information on vegetarian diets in pregnancy and how/why/what nutrients should be considered. This topic has also come up repeatedly in podcast interviews.
Two specific interviews where I discuss why I endorse an omnivorous diet during pregnancy and nutritional considerations if you opt for a vegetarian diet include:
Fertility Friday with Lisa Jack (episode 188). Listen HERE.
Sustainable Dish with Diana Rodgers (episode 64). Listen HERE.
Lastly, I have a lengthy section on the challenges of a vegetarian diet in pregnancy in Real Food for Pregnancy with 55 citations on that topic alone (see Chapter 3). This isn’t about pushing a certain dietary agenda; it’s about separating fact from fiction. It’s about protecting the health of mothers and babies. The above article includes excerpts from this section of the book; the book goes into detail on all of the nutrients of concern listed here and much, much more.
Real Food for Pregnancy (see Chapter 3). Buy HERE.
When I was writing this section of the book, I was keenly aware that many readers would have had experience with a vegetarian diet (or currently be eating a vegetarian diet), so you can rest assured, this is a non-emotional, purely evidence-based discussion on this topic. I simply want you to be armed with the most accurate information when making decisions about your diet during pregnancy.
So far, the feedback I’ve received from vegetarian readers have been positive, such as this one:
“I was recently pregnant for the first time (I unfortunately had a miscarriage) and this is exactly the book I had been searching for. Real Food for Pregnancy was a difficult book for me to read, in the best possible way. As a longtime vegetarian, it made me confront many of my food choices and preferences head on and acknowledge that they are not even close to optimal for pregnancy. Despite my internal conflict, I walked away from reading this book feeling incredibly empowered. While reading it I wrote down many questions, only to find that Lily devoted an entire chapter to answering my exact question later in the book. Lily provides all the tools pregnant women need to start optimizing their diets immediately. She lays out the science and interprets it into a series of actionable items that each woman can choose to do or not to do, depending on her specific needs.”
—Anna Gajewski, MPH, Research Coordinator, Managua, Nicaragua
I hope this article and these two interviews have helped clarify the nutrients of concern on a vegetarian diet in pregnancy.
Before you go, I’d love to hear your thoughts.
- Do you think a vegetarian diet in pregnancy is a good idea or not?
- What made you come to this conclusion (articles, books, research, friends, healthcare providers, etc.)?
- After reading this and/or listening to these interviews, has your stance changed?
Let me know in the comments below.
Until next week,
PS – Curious to read Real Food for Pregnancy, but not sure you’ll like it? You can read the first chapter for free right HERE.