A Plant-Based Pregnancy

Today, we look at what plant-based foods have to offer for the special dietary demands of pregnancy. In our first story, we compare the breast milk of vegetarian and nonvegetarian women.

A completely plant-based diet is suitable during pregnancy, lactation, infancy, and childhood––a position echoed by the oldest and largest association of nutrition professionals in the world. Ask a couple hundred health professionals though, and as few as one in three appear to know it. Like any diet during pregnancy, it should be well-planned, which means consuming large amounts and a wide variety of plant foods from all the plant food groups––including whole grains, legumes (like soybeans, regular beans, split peas, chickpeas, and lentils), vegetables, fruits, and nuts and seeds. Make sure to get enough calcium from healthy plant-based sources and sufficient vitamin D from sun or supplements. And critically important, make sure you get a regular, reliable source of vitamin B12.. The two books I recommend for raising plant-based families, published by two of my favorite evidence-based dieticians, are Your Complete Vegan Pregnancy by Reed Mangels, and Nourish, co-authored by Brenda Davis.

What data do we have on the impact of a vegan diet on pregnancy outcomes? The vegans had a significantly lower gestational weight gain, by about six pounds, and lower birthweights––but just by a few hundred grams. Both about seven pounds each, within the normal range, with no differences in the rate of preterm birth, nor any significant differences in the umbilical cord blood B12, folate, or iron marker levels between the study groups. This is not surprising, since the vast majority of both groups were taking prenatal vitamins, as they should.

What about the composition of breastmilk from those eating vegan or vegetarian diets? The systematic review has shown that all non-vegetarian, vegetarian, and vegan mothers produce breast milk of comparable nutritional value. Even omega-3s? There was no difference in milk DHA composition by diet group, but that’s not saying much, since over 80 percent of study participants had milk concentrations of the long chain omega-3 DHA below target.

The meat and egg industries like to scaremonger about choline. But wait, this study was written by someone with no conflicts of interest. Liar. The “Competing interests” section has been updated. And surprise, surprise! The author is a member of a meat industry-funded advisory panel. The truth is that there’s just as much choline in the breastmilk of vegans as those who eat eggs or meat.

There is something egg-free, meat-free mothers may not be passing on as much, though: industrial pollutants, like the banned pesticide DDT and cancer-causing PCBs. The highest levels were found in the milk of fish-eaters, and the lowest levels found in the vegetarians. Even just cutting out meat may cut DDT stores in half.

What about mothers who eat strictly plant-based? Their milk is even less polluted. For almost every contaminant, there was no overlap in the range of scores, meaning the highest (worst) vegetarian value was lower than the best (lowest) value obtained in the U.S. sample. And by vegetarian here, they mean women who eliminate all animal products from their diets, including eggs and dairy. The one vegetarian mom who had more than trace amounts in her breastmilk had only been veg for less than a year. But for some of these other toxic pollutants, the average vegetarian levels were only 1 to 2 percent as high as the average levels in the United States. Breast is still best, regardless of the dietary pattern of the mother, but nursing infants of vegetarian women whose diets are low on the food chain––in other words plant-based––have the advantage of being exposed to less chemical pollution.

In our next story, I recommend all pregnant and breastfeeding women follow the consensus guidelines to get about 200mg of preformed DHA from a pollutant-free source.

A systematic review of randomized controlled trials of DHA supplementation of pregnant and breast-feeding women failed to find any clear and consistent short or long-term benefit for psychomotor, mental, visual, or physical development.

Maybe DHA supplementation during pregnancy has no effect because the body isn’t stupid and protects the growth of the baby’s brain by drawing off of maternal stores of DHA, upregulating maternal DHA synthesis, and preferentially shuttling it to the fetus, but what if moms don’t start out with large maternal stores?

In other words, maybe DHA failed to help women who were already getting enough, but maybe women with very low intakes would benefit from DHA supplementation. Well first, it’s interesting to note that even by 1978 researchers were suggesting plant-based diets as the diets of choice in the treatment of our number one killer, but babies breastfed by vegan moms had significantly less DHA in their bloodstreams, presumably because they had significantly less DHA in their breastmilk.

The question is whether these differences are of any consequence? The growth and development of vegan and vegetarian children are normal, as long as they’re getting their B12; no evidence that neural or intellectual functions are impaired. In fact, the two studies we have on vegetarian kids showed they had higher IQ’s, though that may be because their parents tended to be better educated. But even though the kids seemed fine, that doesn’t rule out the possibility that there may be some subtle differences in visual or neural functioning.

It would be interesting to compare the function of babies getting vegan breast milk levels versus general population levels. Vegans had 14,  vegetarians 30, and omnivores 37. This study compared zero to 32, 64, and 96, and 32 worked better than zero, but more than 32 didn’t add anything. This could explain why the general population at 37 doesn’t benefit from additional DHA supplementation, but what about down at 14? Most studies down at that level show no advantage over zero, though one study found a benefit supplementing at as low as 5, but that doesn’t help us.

Now, just because babies breastfed by vegan moms have significantly lower DHA levels in the blood, that doesn’t necessarily mean they have lower levels in their brain, which is where it counts. What we need is a randomized, controlled trial in non-fish-eaters of DHA supplementation. Until then, it’s going to remain uncertain. So, what should pregnant and breastfeeding women who avoid fish do in the meanwhile? Low intakes of DHA doesn’t necessarily equate with fetal DHA inadequacy, but these new data suggest that some infants may not be getting enough and could benefit from their moms supplementing; and so, I recommend pregnant and breast-feeding women on plant-based diets do follow the consensus guidelines to get about 200mg of preformed DHA from an uncontaminated source, like algae oil, which is probably the best combination for all women given the state of our world, to minimize exposure to toxic pollutants such as dioxins, PCBs, and mercury. 

Finally today, we look at the optimal B12 dosage – for kids, pregnant women, and seniors.

Universal improvement of B12 status appears “to be a nutritional imperative with possibly profound beneficial effects,” particularly at the bookends of life—at old age and infancy. I’ve explained the rationale for my recommendations to take vitamin B12 supplements once a week or once a day, or alternately eat sufficient daily vitamin B12-fortified foods. But for those over age 65, those guidelines go out the window. The recommendations change to everyone taking a high daily dose of 1,000 mcg every day.

Starting at age 50, everyone––meat-eaters and vegans alike––should be taking B12 supplements or eating B12-fortified foods. But over age 65, 50 a day may not do it. Even 100 a day doesn’t seem sufficient. Researchers investigated three doses, and found that most didn’t normalize their MMA until after the 1,000 microgram dose. (MMA suppression is a measure of B12 sufficiency.) But they just tested 25, 100, and 1,000. Maybe 250 or 500 would do it?

Researchers set out to find an adequate dose at that age, and it seems we need at least about 650 to 1,000 a day in most people, hence my 1,000-a-day recommendation after age 65.

Okay, what about the other end of the life cycle? The consequences of B12 deficiency and insufficiency can be devastating in infancy and childhood. And this is not just a problem for plant-based pregnancies. “Vitamin B-12 insufficiency during pregnancy is common even in nonvegetarian populations.” About a quarter of all pregnant women aren’t getting enough B12, and that number rises to nearly one in three by the third trimester. But, insufficiency isn’t as bad as frank deficiency, which can manifest in cases like cerebral atrophy, meaning brain shrinkage, in a “Vitamin B12-deficient Infant of a Vegetarian Mother.” Thankfully, even severe brain atrophy can be substantially reversed with B12 supplementation, but better not to become deficient in the first place.

The solution proposed by a group of French pediatricians is to recommend against raising vegan kids at all, since B12 supplementation is necessary. And they’re not alone. To vegan or not to vegan. In 2016, two professional organizations, the U.S. Academy of Nutrition and Dietetics and the German Nutrition Society, issued conflicting statements. The U.S. Academy said that even strictly plant-based diets are appropriate for all stages of the life cycle, whereas the German group echoed the French group, saying since you have to take B12, we can’t recommend a vegan diet for pregnant women, lactating women, infants, children, or adolescents. To confuse the matter further, the American Academy of Pediatrics appeared to have it both ways; in one place repeating the U.S. Academy’s position, while in another place it stated that vegan diets should not be recommended for children. But I think they’re just saying the same thing. Everyone agrees that a non-B12 supplemented plant-based diet is a bad idea—that’s part of what the U.S. Academy means by “well-planned.” Everyone eating plant-based, but especially pregnant and breastfeeding women, must ensure a regular, reliable source of vitamin B12, meaning B12 supplements or B12-fortified foods. But then you may be able to get the best of both worlds.

That’s why there are reviews with titles like this – plant-based pregnancies: danger or panacea? Danger if you don’t take your B12 but “following a plant-[based] diet during pregnancy may be protective against the development of preeclampsia, pre-gravid obesity, and minimize the exposure to [DNA-damaging] agents.” It may also protect our newborns “from the onset of pediatric diseases, such as pediatric wheezing, diabetes, neural tube defects, orofacial clefts, and some pediatric tumors.” “Vegan pregnant women have a lower-than-average rate of cesarean section, less postpartum depression, and lower neonatal and maternal mortality, with no complications or negative outcomes that are higher than average.” In addition, a lower incidence of what used to be called toxemia, a potentially dangerous pregnancy complication known as preeclampsia. “Overall, plant-based diets seem to confer protection to both mothers and newborns” by not only “reducing the risk of several pregnancy-related issues” but decreasing the risk of childhood disease. “Children following plant-based diets might have a lower risk of developing obesity,” obviously are less exposed to drugs used in animal production, and have a favorable anti-inflammatory profile of cell-signaling factors. But again, everyone on a plant-based diet has to get enough B12.

Pregnant and breastfeeding women can just follow my 50 micrograms a day recommendation for nonpregnant adults, or 2,000 a week, though they suggest breaking up those doses into two halves to boost absorption. After infants are weaned, they can start on 5 micrograms a day; from ages 4 through 10 they can take half the adult dose of 25 a day; and then at age 11, they can take 50 a day or 2,000 a week. You don’t have to worry about taking too much. It’s water-soluble and you’ll just end up with expensive pee.