Overview

You have increased nutrient needs during pregnancy, and maintaining a balanced diet is essential for you and your baby. There is no denying that animal products are naturally rich sources of specific vitamins and nutrients, and those following a plant-based diet can still meet their nutritional needs. People choose a plant-based diet for various reasons, including environmental, ethical, or health considerations. This episode examines the evidence on plant-based diets during pregnancy and provides an overview of key nutrients to focus on when following a vegetarian or vegan diet.

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Importance of Diet

The foods you eat should be your primary source of all the vitamins and nutrients you and your baby need. You should also take a prenatal vitamin to fill in any gaps in nutrients that can happen with any diet. This article is an overview of some specific nutrients to pay attention to if you eat a primarily plant-based diet. Several episodes and articles dive deeper into some of these topics.

Controversy of Diets

There are many varying opinions on diet. There is no definitive research to support one ideal diet for everyone, and nutrition is very individualized. This article does not investigate the merits of one diet over another or the benefits or drawbacks of eating plant-based. This provides an overview of things to consider, and I support the diet you think is best for you and your baby.

The Limitations of Research on Diet and Nutrition 

Studies on the long-term effects of consuming any food are complicated because of many variables. If you increase your consumption of one food, you will likely decrease your consumption of something else. We do not know whether the change in health or disease is related to eating more of one food or less of another.

Another challenge with research on nutrition and diet is that most studies rely on questionnaires that require participants to self-report the foods they consume. The problem is that the reporting is typically not very accurate. On top of the challenges of having an evidence-based approach to the right diet, there is no one-size-fits-all. We have different dietary needs based on our genetic makeup, where we live, our levels of activity, our health, and so on. 

Increased Nutrient Requirements in Pregnancy

During pregnancy, you have many increased requirements for nutrients. You have increased energy demands, and you must supply your baby with everything they need to grow. A systematic review that examined 22 papers on vegan and vegetarian diets during pregnancy concluded that the evidence on vegan–vegetarian diets in pregnancy is heterogeneous and scant. The lack of randomized studies prevents us from distinguishing the effects of diet from confounding factors. Within these limits, vegan-vegetarian diets may be considered safe in pregnancy, provided that attention is paid to vitamin and trace element requirements.

Dietary Reference Intake

Dietary Reference Intake is the general term for a set of reference values used to plan and assess the nutrient intakes of healthy people. The Food and Nutrition Board of the Institute of Medicine and the National Academy of Sciences set these values. The values vary by age and sex and by whether you are pregnant or breastfeeding.

• Recommended Dietary Allowance (RDA): average daily intake level sufficient to meet the nutrient requirements of nearly all (97%-98%) healthy people. 
• Adequate Intake (AI): established when evidence is insufficient to develop an RDA and is set at a level assumed to ensure nutritional adequacy. 
• Tolerable Upper Intake Level (UL): maximum daily intake unlikely to cause adverse health effects.

Plant-Based Diets

There are a variety of diets that fit within the plant-based category. These exclude some or all animal products and focus on fruits, vegetables, grains, nuts, seeds, and legumes. The strictest plant-based diet is vegan, with no animal products, eggs, dairy, or honey. Other variations of a vegetarian diet may allow for honey, dairy, and eggs. A lacto-ovo vegetarian diet is primarily plant-based and allows for dairy, eggs, and honey. Lacto vegetarian includes dairy and honey but no other animal products. Ovo vegetarian allows for eggs and honey. A pescatarian diet is mainly plant-based but includes fish, dairy, eggs, and honey.

People choose to eat a plant-based diet for many reasons, including environmental, ethical, or health reasons. Simply avoiding meat or animal products does not necessarily make a vegetarian diet healthy. Like any diet, it should focus on healthy, whole foods and limit processed foods and sugar.

Considerations When Cutting Out Animal Products

Regardless of your reasons for eating a plant-based diet, there is no denying that many animal products are rich in vitamins and nutrients. You must get nutrients from other sources if you avoid meats, seafood, eggs, or dairy. While it is possible to eat a healthy diet that does not include animal products, you must be mindful to ensure you are getting the nutrients you and your baby need. Let’s examine some of the vitamins and nutrients you should focus on.

Protein

Protein is made of amino acids and is in almost all parts of your body. Protein does more than build muscle mass; it is necessary to structure, function, and regulate virtually all tissues in your body. For anyone not educated about plant-based diets, the first thing they think of is that you cannot get enough protein without meat. That is simply not true.

For someone not pregnant, the Recommended Daily Allowance (RDA) for protein is 0.80 grams per kg of body weight or about 0.8 grams for every 2.2 pounds. Your physical changes and your baby’s growth are considered to calculate how much protein you require during pregnancy. The RDA for pregnant women is 1.1 g of protein per kg (2.2 pounds) of body weight. For an expecting mom who weighs 150 lbs (about 68 kg), the RDA for protein is about 75 grams of protein per day. This is about an additional 21g/day over pre-pregnancy requirements.

Protein in animal products is considered “complete protein” because it includes all nine amino acids. Proteins from plants usually lack one or more of these amino acids. In the past, it was thought you needed to combine foods, like rice and beans, in the same meal to get a complete protein. We now know this is not true, and as long as you eat a wide variety of plant-based foods, you should get all the essential amino acids.

If you cut out meat but are comfortable eating eggs or dairy, those are high in protein. An egg has about 6 grams of protein, and 4 oz. of milk has almost 11 grams. If you avoid eggs and dairy, other plant sources high in protein are legumes, nuts, and seeds. Beans can range between 7-40 grams of protein per cup, depending on the type of bean. Soy 8-33 grams per cup, depending on whether it is raw or cooked and the kind of soy. Half of a cup of tofu has almost 22 grams of protein. One cup of almonds is about 29 g of protein, and one cup of sunflower seeds has 23 g of protein. Nearly all foods contain some amount of protein. To find out how much protein is in a particular food, you can view a comprehensive list of protein content in foods from the USDA.

Soy

In recent decades, soy has emerged as a staple in plant-based diets, primarily because of its high protein content. If you eat soy regularly, you should be aware of some of its properties.

94% of the soy grown in the United States is genetically modified. GMO crops are designed to be resistant to glyphosate, a potent herbicide, and soy is high in glyphosate residues. To avoid GMO soy, look for organic or non-GMO products.

Soy is high in phytic acid, which inhibits the absorption of other nutrients like calcium and iron. Lily Nichols has a great post with five reasons to avoid soy during pregnancy and links to evidence. I recommend you read it if you regularly eat soy.

Soy also contains phytoestrogens, plant-based compounds that work like estrogen in the body. You have higher levels of estrogen during pregnancy than you do during your entire non-pregnant life. One study found that consumption of soy increases phytoestrogens in amniotic fluid. Other research points to phytoestrogens affecting reproductive health. Hopefully, we will have more data on how soy could affect you or your baby during pregnancy.

You can reduce how many foods you consume that have soy as an ingredient. You could also opt for fermented soy, like tempeh and natto, which aren’t processed and are easier to digest.

Protein Powder 

Protein powder is an easy solution to adding more protein to your diet, and many plant-based protein powders are available. If you consume protein powders, there are some other ingredients you may want to pay attention to.

Many protein powders use artificial sweeteners rather than sugar. Overall, we do not see detrimental effects from non-nutritive sweeteners. There are some red flags showing concerns about gut microbiome health and the impact of non-nutritive or artificial sweeteners on future preferences for sweet foods. Most of the studies have been on animals, and in the future, we should see more evidence of the long-term use of these additives in humans. For an in-depth analysis of natural and artificial sweeteners, see this article.

Some protein powders contain GMOs, usually from maltodextrin derived from corn. You can always opt for an organic or non-GMO powder to avoid GMOs.

A study done by the Clean Label Project tested 134 of the top-selling protein powders and found many of them contained heavy metals like arsenic, lead, and cadmium. These are most likely from the soil ingredients are grown in. Over 50% of the products tested contained BPA, a known endocrine disruptor, likely from the packaging. Organic products, on average, had twice the heavy metals than non-organic. 75% of the plant-based proteins tested positive for lead. Protein powder is a supplement and should be used to supplement a well-balanced, healthy diet. This is an easy solution to add additional protein, and you should be cautious about the protein powder you buy and how much you consume.

Supplementing a Plant-Based Diet

If you eat a primarily plant-based diet, you should be mindful of some vitamins and nutrients. You can get all these nutrients by eating or supplementing certain foods, but they are commonly deficient in vegetarian or vegan diets.

B-12

You need vitamin B-12 (cobalamin) for blood formation and neurological function. This is an essential vitamin that is only in animal products. The good news is that you can supplement with B-12. The RDA for B12 is 2.4 mcg per day for women between 19-50. During pregnancy, your absorption of B12 increases, and the RDA during pregnancy is slightly lower 2.2. mcg per day. When breastfeeding, your baby is also relying on you for B12. The RDA for breastfeeding mothers is 2.6 mcg per day. Research shows that B12 in breast milk is lower in vegetarian mothers. If you are eating a primarily plant-based diet, you must supplement with B12. There have not been adverse effects associated with excess B12 in healthy individuals. Your prenatal vitamin should include a high amount of B12. You will see B-12 listed on the ingredients as either cyanocobalamin or methylcobalamin. Cyanocobalamin is considered more stable and cheaper. Higher quality vitamins (like the Zahler Prenatal +DHA) include methylcobalamin.

Vitamin D

Vitamin D helps with the absorption of other vital nutrients like calcium, iron, magnesium, phosphate, and zinc. It also regulates immune function, cell growth, and neuromuscular function. You need vitamin D during pregnancy to help deliver calcium to your baby’s developing bones.

Animal foods tend to be the highest source of vitamin D. While vitamin D may not be abundant in plants, one study found that other factors, such as supplementation, degree of skin pigmentation, and amount and intensity of sun exposure, have a greater influence on vitamin D levels than diet. Whether you eat meat or animal products, vitamin D deficiency is common, and you should ensure you are getting enough.

A study that examined vitamin D deficiency during pregnancy found 97% percent of Blacks, 81% of Hispanics, and 67% of Caucasians were deficient. Research identifies vitamin D deficiency as a risk factor for preeclampsia. Evidence also links vitamin D deficiency with increased odds of primary cesarean section. Another study examined how maternal vitamin D deficiency could affect a baby later in life. A deficiency was associated with impaired lung development in 6-year-olds, neurocognitive difficulties at age 10, increased risk of eating disorders in adolescence, and lower peak bone mass at 20 years. There is an in-depth analysis of vitamin D in this episode.

Iron

Iron is a component of hemoglobin, a substance in your red blood cells that carries oxygen from your lungs throughout your body. During pregnancy, your blood volume increases by 50%, which requires a lot of iron. When you are not replacing iron as quickly as your body uses it, you have a deficiency. If you are deficient in iron during pregnancy, it can cause premature labor or your baby to have a low birth weight and impaired cognitive and behavioral development.

According to the American College of Obstetricians and Gynecologists, the daily recommended dose of iron during pregnancy is 27 mg. The foods with the highest amount of iron are animal products. Thankfully, most prenatal vitamin supplements contain iron. Plant-based iron-rich foods include dried beans and peas and iron-fortified cereals. Iron also can be absorbed more easily if you eat iron-rich foods with vitamin C-rich foods. Check out this episode for more information on iron during pregnancy and breastfeeding.

DHA

DHA (docosahexaenoic acid) is an omega-3 fatty acid. DHA is a major structural fat in the human brain and eyes. DHA represents about 97% of all omega-3 fats in the brain and 93% of all omega-3 fats in the retina. DHA is crucial for your baby’s brain and retinas to develop during the third trimester and up to 18 months of life.

Research also shows that getting sufficient omega-3s is essential because it is associated with improving neurodevelopmental outcomes, decreasing the risk of infant allergies, preventing preterm birth, preventing depression during pregnancy, and preventing postpartum depression. Evidence also shows that supplementation with omega-3s has been found to increase children’s IQs.

A lot of factors influence DHA levels. Your body will convert a minimal amount of other omega 3s (ALA and EPA) to DHA. 4-11% of the DHA you get from your diet is also retro-converted to EPA. The ratio of omega 6s to omega 3s can impact how much other omega 3s your body converts to DHA. This process is already not efficient. Your body cannot make adequate DHA levels; you need to get it from your diet or a supplement.

If your diet includes fish, that is the best source of DHA. If you include eggs in your diet, those will include omega 3s. If you see a label that each egg has 225 mg omega 3s, not all of that is DHA. Plant-based foods with omega 3s contain ALA but not DHA and EPA. If you are not eating seafood regularly, you should supplement with DHA.

There is no universally recommended daily allowance for DHA. Most of the literature I reviewed suggested a range of 500-1000 mg of omega 3s per day, and roughly half of that should be DHA. The most common suggestion is between 200-300 mg of DHA daily. DHA can come from either fish oil or algae. In recent years, a few prenatal vitamins have caught up to the science and include DHA, but most do not. If you want to avoid consuming fish, you can look for a supplement made from algae. The Zahler Prenatal sources its DHA from algae. If you want a vegan DHA supplement, this one is my favorite. There is an entire episode on Omega 3s with more information on that topic.

Zinc

Zinc is an essential mineral for cellular metabolism and your immune system. Since your body does not store zinc, you need it regularly from your diet. A systematic review found vegetarian diets lower in zinc than those that included animal products. Other studies show no difference in zinc levels between a vegetarian diet and one that includes meat. Eating meat and animal products makes it easy to meet the requirements for zinc. Even on a plant-based diet, you can get plenty of zinc from foods like cereals (fortified with zinc), grains, legumes, seeds, and nuts. The RDA for zinc during pregnancy is 11 mg daily; most prenatal vitamins include that amount or more.

Calcium

Calcium is critical during pregnancy because you supply calcium to your baby to build their bones, with most of that transfer in the third trimester. The AI during pregnancy is 1,000 mg daily, the same amount for a woman even if you are not pregnant. While your calcium requirements don’t increase during pregnancy, your ability to absorb calcium does.

Most prenatal vitamins include around 10% of the adequate intake, and most calcium should come from your diet. The top calcium-rich foods are dairy products like milk, cheese, and yogurt. If you omit dairy from your diet, you can also get calcium from foods like green leafy vegetables, beans, and plant-based milk.

Evaluating How You Feel

A good measurement of how well you are eating is how you feel. Pregnancy can come with fatigue and nausea that have nothing to do with your diet. Eating a wide variety of foods can be challenging if you are experiencing morning sickness. Hopefully, as nausea subsides towards the end of the first trimester, you can return to eating more variety. Eating healthy whole foods should make you feel better than a diet high in sugar or processed food.

Food Cravings During Pregnancy

Many expecting mothers experience different food cravings during pregnancy. There is some speculation that if you crave a particular type of food, your body is trying to balance a nutrient deficiency. For example, if you are craving oranges, you need more vitamin C. Research doesn’t support that theory, and food cravings are likely psychological.

What if you are vegetarian or vegan and you crave meat? This dilemma can be challenging for someone who eats plant-based food for ethical reasons. If you do choose to add in some animal products, you can opt for ethically raised animals. Companies like Butcher Box focus on sourcing meats from ethical and sustainable farms. Ultimately, you should do what you feel is right for you. That could mean veering away from a plant-based diet or sticking to it.

Keeping Track of Your Diet

Keeping a food journal is a powerful tool for ensuring you get enough of the necessary vitamins and nutrients. You don’t have to do this for your entire pregnancy, but even keeping track of meals for a week and seeing how nutrients stack up can indicate whether you lack something. You don’t need a spreadsheet to track every single nutrient. A note on your phone or using an app may be beneficial to make sure you are getting enough protein or other vital nutrients.

Your Baby on a Plant-Based Diet

For the first six months of your baby’s life, their source of nutrition is solely from breast milk or infant formula. If you are breastfeeding, you should ensure you eat a healthy diet because you are supplying your baby with all of the vitamins and nutrients they need. Everything in this article about eating a plant-based diet during pregnancy also applies to breastfeeding. You could opt for a plant-based formula if you supplement with infant formula. The majority of vegetarian or vegan formulas are soy-based.

The use of soy as the primary ingredient in some infant formulas goes back over 100 years. In recent years, questions have been raised about the high consumption of soy due to its estrogenic effects. The American Academy of Pediatrics last updated its opinion on soy-based formulas in 2008. They state that in term infants, although isolated soy protein-based formulas may be used to provide nutrition for normal growth and development, there are few indications for their use instead of cow milk-based formula. These indications include (a) for infants with galactosemia and hereditary lactase deficiency (rare) and (b) in situations in which a vegetarian diet is preferred. Since that 2008 statement, more recent research found that babies fed soy-based formula have changes in reproductive system tissues. We can expect to see more research in this area in the future. Please discuss any questions about your baby’s diet and nutrition with your pediatrician.

Talk to Your Doctor or Midwife

In 1985, the National Research Council’s Committee on Nutrition in Medical Education recommended a minimum of 25 hours of nutrition education in medical school. Given what we have learned about nutrition and diet over the past 35 years, this recommendation should likely be increased. Plus, add many years in between medical school and practice, and some of the learned information may be outdated.

Despite the long-standing 25-hour recommendation, most medical students are not receiving adequate education in this area. According to one report that surveyed 121 medical schools in the United States, 71% do not meet the 25-hour recommendation. 36% provide less than half of that. The lack of education in diet and nutrition is not just a problem in the United States. A systematic review of 24 studies found that medical students are not receiving adequate nutrition education in countries worldwide.

Even though most schools lack sufficient education, some medical professionals educate themselves about diet and nutrition. Hopefully, your care provider is knowledgeable and up-to-date on nutrients, vitamins, and diet. If you have any questions about your diet or whether you are meeting the requirements for nutrients you and your baby need, please talk to your doctor or midwife. If you are not getting sufficient answers to your questions, you may need to consult a dietician or do your research to advocate for yourself. If you are concerned that you are deficient in vitamins or nutrients, you can always request testing. You can run a panel on a blood sample to determine your levels of all the needed vitamins and nutrients.

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