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Should Pregnant and Breastfeeding Women Take DHA Supplements?

One of the reasons breastfed 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 do not, based on data I discuss in my video Should Pregnant and Breastfeeding Women Take DHA?. Infants given control formula without DHA didn’t do as well as those given DHA-fortified formula, and neither group did as well as the breastfed infants, who serve as the “gold standard.” 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 the amount that is naturally found in breast milk. However, the DHA level in breast milk is extremely variable depending on what the mom is eating. There are a number of healthy populations who don’t eat any seafood, for example, and they have much lower levels in their milk yet seem fine. So this 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” of DHA daily during pregnancy. “Simply encouraging pregnant women to eat more fish is not so simple, because most fish are to some extent contaminated” with toxic pollutants, such as mercury. (See my video Mercury vs. Omega-3s for Brain Development for more on this.) For most fish, such as tuna, the brain damage caused by the mercury would exceed the benefit from the DHA.

Additionally, some pollutants, like PCBs, can get stuck in our bodies for decades, 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 when 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 eventually get it from themselves. 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.

Until recently, we thought everyone should take these long-chain omega-3s for their heart. However, the balance of evidence is now such that doctors “should not recommend fish oil intake or fish consumption solely for the primary or secondary prevention of CHD,” coronary heart disease. But what about for expectant and breastfeeding mothers? What does the latest science show? Putting all the studies together, it turns out adding DHA to formula does not appear to help infant cognition after all, similar to other recent compilations of evidence that show “no significant benefit.” In fact, at least four meta-analyses, or systematic reviews, have reached a similar conclusion. These were based mostly on the standard series of measurements known as the Bayley Scales for Infant Development. If other tests were used, would there be different results? So far, no. 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 benefit to 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 trials that showed benefit had some problems. So, while we really don’t know at this point, if all the studies so far show either nothing or benefit, why not just take them to err on the side of caution?

There may not be any demonstrable “clear and consistent” benefits, but there are 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 800mg of DHA a day during pregnancy, infant “girls exposed to higher-dose DHA in utero [in the womb] had lower language scores and were more likely to have delayed language development than girls from the control group.”

So, the “absence of clear positive effects and the possible presence of negative effects in the children raise the question whether DHA supplementation is justifiable…” But it was a really large dose, suggesting that there may be “an optimum DHA level below and above which DHA might be detrimental to the developing brain.”

So, maybe too much is detrimental, but what about too little? I discuss that in Should Vegan Women Supplement with DHA During Pregnancy.

Other videos on the concerns about the pollutants in the aquatic food chain include:

For more on fish oil, see:

In health,
Michael Greger, M.D.



Michael Greger M.D., FACLM


22 responses to “Should Pregnant and Breastfeeding Women Take DHA Supplements?

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  1. I would be interested in seeing a trial comparing omega 3 levels in the bloodwork of wfpb people with the bloodwork of say mediterranean diet people to see where their actual levels are, unsupplemented. The cost of supplements here make it out of the question, except maybe krill oil on sale or something. Dr Ornish has a slightly different view (this article written by one of his writers)

  2. Swordfish was banned during the 1970’s due to high levels of mercury. Under intensive lobbying from the fishing industry, the Reagan administration raise the allowable levels of mercury in swordfish. Swordfish was back on the market.

    1. Blair, it’s appalling! I am so grateful to Dr Greger for the mini education I have received during this wfpb journey. I was (and still am) so naive when it comes to the political underpinnings of our dietary guidelines and food environments.

      I am enjoying learning more about omega 3s this morning. Here, I found what I was looking for, and that is conversion rates of ALA , and factors that influence it. More notes on the pollution also. I was surprised to see women convert ALA better than men apparently…

      1. Thanks Barb,

        That was interesting!

        The concept that I found interesting was that the DHA from ALA increases over time. So if a woman is thinking of becoming pregnant, she should maybe increase her sources of ALA for the year before pregnancy? Maybe?

        “Research has shown that 3 grams (the equivalent of 2 tablespoons of ground flaxseed or about 1-1/2 teaspoons of flaxseed oil) per day of ALA does not increase blood percentages of DHA in the short term, but it may over a longer period of 10 months or more.”

        1. This sentence also intrigued me:

          “A 2010 study in the American Journal of Clinical Nutrition found that the blood levels of EPA and DHA in vegans and vegetarians were approximately the same as regular fish eaters. This finding indicates that the bodies of vegetarians and other non-fish-eaters can perhaps respond to a lack of dietary Omega-3 EPA and DHA by increasing their ability to make them from Omega-3 ALA.”

        2. Hi Deb, yes, I find it all fascinating ! If we just eat what we are meant to eat, the body figures it out. The thing I noticed too was that while women are more efficient converters of ALA to EPA and DHA than men, I need to be mindful of the omega 6 to omega 3 in my diet if I want to avoid supplements if possible.

          1. I am not at all consistent with supplements, so it made me happy that women were more efficient converters of ALA.

            A while back, I had read a study where the results were “inconsistent” for converting ALA to DHA and they were talking about brain function, so it was a big deal. Emotionally, the 10 months is a game-changer for me.

        3. Note that this is “may” increase rather than “does” ….. but it is plausible.

          The next question of course is that, if we supplement with algal DHA/EPA, does the body dial down its efficiency in converting ALA to DHA as it appears to do in fish eaters?

          1. Mr Fumblefingers, that thought did occur to me, but I have not seen anything written about it. It does inspire me to take a second look at how I might be messing up the ratios though and tweek my diet accordingly.

    2. Blair,

      Some of us have never heard about any of it.

      I remember the song by Cat Stevens “Where Do the Children Play?”

      I don’t understand what the children will do when the seas and soil and air are all so toxic that disease strikes so early?

      I watched Michael Buble talking about his son getting Cancer at 3 years old.

      My heart goes out to young people.

  3. We switched from fish oil to algae omega 3 because of the fish oil pollution issue. However, the vegan oil gave us a fishy aftertaste, and when we cut open one of the capsules it smelled just like salmon. Is it normal for vegan omega 3 to smell like fish (like, because algae smell fishy to begin with, or something)?

  4. When I was pregnant with my son I was vegetarian, took organic spirulina, and he turned out fine, he is a healthy and intelligent teenager now.

  5. I know this blog is only very recent but it appears to be already out of date? This review has found significant reductions in premature birth rates as a result of EPA/DHA supplementation. Australian authorities are now considering updating their recommendations to expectant mums as a result…

    It would be great if Dr Greger could provide some comment on this new evidence.

  6. There is no such thing as “expired” or “out of date” research. There is only disproved research. Nothing Dr. G has reported/blogged about has been disproved, so his reports are still highly relevant.
    The endpoints of the study you linked are not “hard”. Hard endpoint are things like premature death and other highly relevant criteria. That was not measured in your referenced study, only low preterm birth-weight, length of pregnancy and preterm birth rate. It seems like reducing the incidence of these issues might be good, but who knows? Maybe these babies would have gone on to have lower rates of intelligence or higher rates of cancer? We don’t know, so there is no concrete evidence of true “benefit.” I think it does suggest “further studies are needed” but with more relevant endpoints.

    Dr. Ben

    1. Fully agree on the ongoing research but can’t agree on the endpoints. Birth at 21 weeks is at the very edge of viable life. This study shows a much reduced risk of that outcome for mothers taking these supplements. It doesn’t get any “harder” than that endpoint…

      Expectant mums would be extremely interested in this research – in my opinion this blog should be updated to reflect it.

    1. Extreme premature birth is a well known marker for infant health outcomes in the same way that blood pressure is a marker for adult health. I’ve seen Dr G cover blood pressure plenty of times – as well as other things with a far lesser link to obvious health outcomes.

      The blog should be updated to reflect this significant new evidence.

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