Should Plant-Based Women Supplement with DHA During Pregnancy?

A systematic review of randomized controlled trials of DHA supplementation of pregnant and breastfeeding women failed to find any clear and consistent short- or long-term benefit for psychomotor, mental, visual, or physical development. Perhaps DHA supplementation during pregnancy has no effect because the body wisely 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 perhaps women with very low intakes would benefit from DHA supplementation. My video Should Vegan Women Supplement with DHA During Pregnancy? explores the evidence available to date.

It’s interesting to note that, by 1978, researchers already were suggesting a plant-based diet as the diet of choice in the treatment of our number-one killer, heart disease, but babies breastfed by vegan moms had significantly less DHA in their bloodstreams, presumably because the moms had significantly less DHA in their breast milk.

The question is whether these differences are of any consequence. The growth and development of vegan and vegetarian born children are normal as long as they’re getting their B12, and “[t]here is no evidence that neural or intellectual functions are impaired.” In fact, the two studies we have on kids in vegetarian communities showed they had higher IQs, though that may be because their parents tended to be better educated. However, 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. In one of the studies I profile in my video, it shows that vegans hit a level of 14, vegetarians 30, and omnivores 37. Another study compared 0 to 32, 64, and 96, and, though 32 worked better than 0, 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 at that level show no advantage over 0, though one study found a benefit supplementing at as low as 5, but that doesn’t help us.

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 intake of DHA doesn’t “necessarily equate with fetal DHA inadequacy,” but new data suggest that some infants may not be getting enough and could benefit from their moms supplementing. Given this, I recommend pregnant and breastfeeding women on plant-based diets to 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.

To gain a better understanding of why algae oil is better than purified fish oil, I encourage you to watch my video Should Pregnant and Breastfeeding Women Take DHA.

I’ve discussed concerns about pollutants in seafood during pregnancy in a number of my videos:

Finally, for more on taking long-chain omega-3s to protect your heart, see:

In health,
Michael Greger, M.D.

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