 I know you work hard to make the best lifestyle choices, so you can improve your health, destiny, and longevity. And there's lots of information out there on how to do just that. So where do you start? Well, we start with the facts. Welcome to the Nutrition Facts Podcast. I'm your host, Dr. Michael Greger. My job is to bring you the latest peer-reviewed nutrition and health research, and share it with you here. Today, we look at the long-chain omega-3 fatty acid DHA that plays an important role in supporting pregnant and breastfeeding women. In our first story, we discover how DHA improves the development of infants. One of the reasons breast-fed infants may have better cognitive and visual development is because human milk contains long-chain polyunsaturated fatty acids, like the omega-3 DHA. While most available infant formulas did not, where infants given control formula without DHA didn't do as well as those given DHA fortified formula. Neither did as well as the breast-fed infants who serve as the gold standard. But this was enough to convince formula manufacturers to start adding DHA to their infant formula starting back in 2002. The question then became how much to add? Easy, right? Just add however much is naturally found in breast milk. However, the DHA level in breast milk is extremely variable, depending on what the mom is eating. For example, there's all these healthy populations that don't eat any seafood and have much lower levels in their milk, and they seem fine, so that makes it difficult to determine the optimal amount to add to formula. Or for that matter, what to recommend for pregnant and breastfeeding women. Consensus guidelines recommend that women should aim to consume an average of 200 mg a day of DHA during pregnancy. Of course, this isn't as simple as encouraging women to eat more fish because of the toxic pollutants, such as mercury, such that for most fish, such as tuna, the brain damage caused by the mercury would exceed the benefit from the DHA. And some pollutants like PCBs can get stuck in our bodies for decades, and so it's not enough to just eat clean during pregnancy. What about purified fish oil? The methods supplement manufacturers use like distillation leave considerable amounts of PCBs and other pollutants in the products, so much so that, taken as directed, salmon, herring, and tuna oils would exceed the tolerable daily intake of toxicity. Thankfully, one can get the benefits without the risks by getting DHA from algae instead, which is where the fish get it from, and so pregnant and breastfeeding moms can cut out the middle fish and get DHA directly from the source at the bottom of the food chain where we don't have to worry about toxic pollutants. But until recently, we thought everyone should take these long chain omega-3s for their heart, but the balance of evidence is now such that doctors should no longer be recommending fish oil intake or fish consumption solely for prevention of coronary heart disease. But what about forexpectant and breastfeeding mothers? What's the latest science show? Put all the studies together, and turns out adding DHA to formula does not appear to help infant cognition after all, similar to other recent compilations of evidence that showed no significant benefit. In fact, at least four meta-analyses or systematic reviews have reached a similar conclusion. Now, these were mostly based on a standard series of measurements known as the Bailey scales for infant development. Their tests were used, there'd be different results, but so far no luck giving women DHA supplements during pregnancy did not appear to help with other outcomes like attention span or working memory either. Although there may be no significant benefits for infant cognition, what about other things, like vision? Six trials have been done to date supplementing pregnant women. Four showed no effect, and the two that showed benefit had some problems, and so we really don't know at this point. But hey, if all the studies so far show either nothing or benefit, why not just take them on the side of caution? Yeah, no demonstrable clear and consistent benefits, but there's new studies on this coming out all the time. If it's harmless, maybe women should just take it to be on the safe side. The problem is that it may not be harmless in large doses. In a study in which women were given a whopping 100 mg of DHA a day during pregnancy, infant girls exposed to the higher dose DHA in the womb had lower language scores and were more likely to have delayed language development than girls from women in the control group. So the absence of clear positive effects, along with the possible presence of negative effects, in the children raised the question whether DHA supplementation is justifiable. But it was a really large dose, suggesting that there may be an optimal DHA level below and above which DHA might be detrimental to the developing brain. So maybe too much is detrimental. What about too little? I'll cover that next. 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 cycle motor, 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 drying off 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 diet of choice in the treatment of our number one killer, but babies breastfed by vegan moms have significantly less DHA in their bloodstream, 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 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 that they had higher IQs, though that may have been because their parents tended to be better educated. But even though the kids seem fine, it doesn't rule out the possibility that there may be some subtle differences in visual or neural functioning. It'd be interesting to compare the function of babies getting vegan breast milk levels versus general population levels. Vegans had 14 vegetarians, 30 omnivores, 37. Now, just because babies breastfed by vegan moms have significantly lower DHA levels in the blood doesn't necessarily mean they have lower levels in their brain, which is where it counts. What we need is a randomized control 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 this new data suggests that some infants may not be getting enough and could benefit from their mom's supplementing. And so I recommend pregnant and breastfeeding women and plant-based eyes do follow the consensus guidelines to get about 200 milligrams 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. We would love it if you could share with us your stories about reinventing your health through evidence-based nutrition. Go to nutritionfacts.org slash testimonials. We may share it on our social media to help inspire others. To see any graphs, charts, graphics, images, or studies mentioned here, please go to the Nutrition Facts podcast landing page there. You'll find all the detailed information you need, plus links to all the sources we cite for each of these topics. For a vital, timely text on the pathogens that cause pandemics, you can order the e-book, audiobook, or the hard copy of my last book, How to Survive a Pandemic. 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