To DHA or not DHA when pregnant?
November 23, 2013 7:22 AM   Subscribe

Hello! My wife is pregnant with our first child (second trimester.) She's been taking a DHA supplement (Nordic Naturals PreNatal) for prenatal brain development, but has suddenly gotten worried about whether it's good to take a DHA supplement. Our doctor/nurse pretty much has no advice on this matter. Now my wife is worrying about mercury/lead though we can't find any evidence that this actually exists in fish oils, or Nordic Naturals in particular. Take it or not?

Scientists out there or people more capable of rational thought than we are at this point: do you think it's worth it to take the DHA for brain development? Or should we just stop for peace of mind? Keep in mind, my wife doesn't ever eat fish, really.

Any thoughts would be much appreciated!
posted by EtTuHealy to Health & Fitness (18 answers total) 4 users marked this as a favorite
I have a hard time believing the FDA would be fine with allowing any mercury whatsoever in prenatal supplements.

Prenatal supplements are in general a good idea though - pregnant women can easily become anemic, for example, and supplements help prevent that.
posted by kavasa at 7:28 AM on November 23, 2013

My understanding is that fish oil supplements are designed to be mercury-free.
posted by amanda at 7:31 AM on November 23, 2013

Response by poster: Yes, that's my thought too, though the FDA apparently is pretty lax about regulating vitamins. Oh, and she is taking a general prenatal supplement as well. Thanks!
posted by EtTuHealy at 7:40 AM on November 23, 2013

I thought pregnant women are supposed to take DHA? It's in my prenatal vitamin as well, FWIW.
posted by amro at 7:43 AM on November 23, 2013 [2 favorites]

Keep in mind that the stuff you get in prenatals isn't just for the baby. My midwives prescribed me a fish oil supplement specifically to counteract the binding effects of the iron I've been taking for my pregnancy-related anemia.
posted by PhoBWanKenobi at 7:43 AM on November 23, 2013

I'm 7 mths pregnant, and have been taking it without any concerns. I went with Spectrum Essentials, which isn't fish oil based, only because I wasn't keen on any fishy tasting burps back when that was a possibility. So maybe that's an option.
posted by bizzyb at 7:51 AM on November 23, 2013 [1 favorite]

The DHA I took during pregnancy was made from a plant source rather than an animal source--that might give her more peace of mind.
posted by katypickle at 8:17 AM on November 23, 2013 [1 favorite]

Best answer: I'm a week away from my due date, and I've been taking vegetarian DHA the whole time. I chose to take the vegetarian version because I'm vegetarian, but it allowed me to side-step concerns about mercury. (The FDA does not regulate supplements as closely as other things - see here.) However, a research paper from 2003 suggests there's little mercury in most commercial fish oils.

The upsides of taking vegetarian DHA:
-no fishy taste
-no mercury

The downsides:
-generally not as concentrated; comes in capsules instead of a bottle, you have to take a lot of them if you want to be consuming 1 g DHA or something like that

Oh, and as a neuroscience PhD student I've read the evidence on DHA and brain development pretty carefully. There's no general consensus yet, but after a lot of consideration my feeling was that DHA was the one "extra" supplement (aside from my prenatal vitamin) that I thought it was important for me to take. It definitely doesn't hurt, and it might make a significant difference.
posted by Cygnet at 8:32 AM on November 23, 2013 [3 favorites]

Best answer: Nordic Naturals is known for the best purity testing when it comes to fish oil. They work very hard to make sure that their product has no mercury or PCB contamination and they're transparent about it if you call them or read their website. I'd take it while pregnant with absolutely no hesitation. Vegetarian sources (usually flax seed oil) require a much higher dosage to get the same benefit. I think that the Spectrum dosage is six capsules to be equivalent to one capsule of NN fish oil.
posted by quince at 9:10 AM on November 23, 2013 [2 favorites]

Vegetarian sources (usually flax seed oil) require a much higher dosage to get the same benefit

Just to clear this up: Vegetarian DHA is made from algae, which is where the fish get the DHA in the first place. DHA is DHA no matter what your source - vegetarian or not, the same amount of DHA does the same amount of good. Flax seed oil, however, does NOT contain any DHA at all - it contains ALA, which the body can convert into DHA, but not very efficiently at all, which is why if you were taking only flax seed oil, you would need far more.
posted by Cygnet at 9:19 AM on November 23, 2013 [6 favorites]

My OB recommended that I take DHA, and Rainbow Light and Nordic Naturals were actually the two brands she mentioned to me. I took Rainbow Light and people are constantly commenting on how six month old baby echo is so alert and looks like she is going to be really smart. I'm not saying that there's any connection between that and the DHA, but it does not appear to have harmed her in any way. She's met all of her milestones and is a really happy, alert, smart baby (and no, I'm not the least bit biased!).

posted by echo0720 at 9:23 AM on November 23, 2013

Best answer:


Raw fish oils contain environmental toxins like mercury that accumulate in a fish during its life span, but these toxins can be virtually eliminated with the use of high quality raw materials and advanced distillation technologies. Nordic Naturals fish oils are molecularly distilled, utilizing a patented enzymatic process that removes any potential environmental toxins (such as heavy metals, dioxins, PCBs, etc.). Independent laboratory testing documents the absence of PCBs, heavy metals, and dioxins in our oils. Certificates of Analysis are available upon request.

(emphasis is mine - if you are worried, call them up ask for the certificate?)
posted by AllieTessKipp at 9:50 AM on November 23, 2013 [2 favorites]

I don't think that this book deals specifically with fish oil, but your wife might find Emily Oster's book, Expecting Better to be helpful (and calming). Oster is an economist who was frustrated all the pregnancy advice that she received that totally lacked the sort of research backing she was used to in her professional life. So she looked into what science really knows about a bunch of pregnancy related concerns and then shows you how you concerned you might want to be and what seems (to her) to be a reasonable strategy based on the evidence. (Giving you enough information about the evidence so you can reach own conclusion)
posted by metahawk at 10:34 AM on November 23, 2013 [2 favorites]

I'm almost 29 weeks pregnant. I have not been taking DHA supplements, because I'm not a fan of how unregulated the vitamin/supplement industry is. (I did make my peace with a brand of prenatal vitamins, but it required a monumental amount of research.) After discussing my diet with my OBs, no one is concerned that the baby is lacking for anything. I get a good amount of DHA and ALA from food sources, so... the end. My OBs are a-okay with my pregnancy nutrition.

I doubt DHA supplements are going to hurt anything, and they may help. I also think your baby is likely to be fine, whether your wife takes DHA supplements or not. But I don't think your wife is being paranoid, or anything. She could eat DHA-fortified foods, if it makes her more comfortable - maybe the fact that food is more regulated than vitamins, will be comforting to her? I'm not sure if that extra regulation amounts to anything, but she could definitely look into it.
posted by Coatlicue at 11:06 AM on November 23, 2013

My prescription prenatal vitamins contained DHA from fish oil. I'm sorry that I can't remember the name, but I'm sure that the FDA is regulating prescribed prenatals. If she decides to keep taking DHA, she might want to ask her medical team for a script for prenatal vitamins with DHA.
posted by PorcineWithMe at 3:53 PM on November 23, 2013

I was prescribed DHA supplements (fish-based I think) specifically because I was expecting and had a preemie. The obgyn was all "do whatever might help" and there was enough and still is to make it a possible bonus. Plus I hate fish. The alternative is to eat a lot of DHA-full food like walnuts and salmon.
posted by viggorlijah at 4:10 PM on November 23, 2013

The NIH echoes that fish oil is "likely safe" in pregnancy as long as it is taken in doses less than 3 grams daily. That's probably as close as the NIH gets to a ringing endorsement.

I'm a doctor and a mother and I didn't take DHA during my pregnancy, but not because I was worried about taking it, I just didn't think there was enough evidence either way that it made a significant difference. My child rearing philosophy is "worry less, enjoy more." I highly recommend it!
posted by treehorn+bunny at 6:56 PM on November 23, 2013

Response by poster: Thanks everyone for the advice! I think we might try the vegetarian route, and ask for a certificate of analysis from Nordic Naturals to be on the safe side.
posted by EtTuHealy at 5:51 AM on November 25, 2013

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