Thursday, October 21, 2010

Fish Oil is Not Magick - But it Might Lengthen Your Pregnancy

I promise that one of these days I will get back to Alzheimer's and saturated fat and ApoE.   Though y'all already know the punchline, right?  Saturated fat is good for you.  But more on that later.

Today I wanted to comment on the JAMA article that was splashed all across the news yesterday.  "Effect of DHA Supplementation During Pregnancy on Maternal Depression and Neurodevelopment of Young Children: A Randomized Controlled Trial."

JAMA is a good journal, and this was a good study.  Called the DOMInO trial, 2399 women were enrolled at less than 21 weeks pregnancy from various Australian perinatal centers.  They were randomized to either 800mg DHA (a type of omega 3 fatty acid that is highly necessary for proper brain function) and 100mg EPA or 800 mg vegetable oil (gak).  Each woman was instructed to take the capsules daily from study entry until birth.  Trial assistants telephoned the women every 6 weeks or so, and at birth the cord blood was measured for DHA levels via gas chromatography.  The moms were screened for postpartum depression at 6 weeks and 6 months after birth, and the kids were screened at 18 months with cognitive scales.   A whopping 96.7% of the women completed the trial, which may be the best completion rate for a large multi-center relatively long term trial I've ever heard.

And the results?  Fewer women in the DHA group complained of postpartum depression, but the result was non-significant (9.67% vs 11.19%).  Mean cognitive scores in the toddlers did not differ either, though fewer children in the DHA group had severely delayed cognition - on the other side, girls from the DHA group had a lower language and "mean adaptive behavior" scores than girls in the control group.   There were fewer preterm deliveries in the DHA group (1.09% vs. 2.25%), but more postterm deliveries requiring induction or C-section in the DHA group (17.59% vs 13.72%).  There was no difference in bleeding or hemorrhage between the two groups.  3.01% of the DHA infants experienced "serious adverse events" (such as admission to the NICU, major congenital abnormality, or death), whereas 4.49% of the control group had serious adverse events - this difference was not significant (p=.06), though the admissions to the NICU piece was significantly worse for the control infants, probably because there were more preterm births.  One other major finding - for the 4% of women who had a history of depression enrolled in the study, the number of the DHA group who had postpartum depression was significantly reduced.

Past epidemiological studies (1)(2) showed a stronger positive effect from fish consumption during pregnancy for a reduction in postpartum depression and an increase in the babies' cognition.  The JAMA editorial from the same issue,  Fish, Fish Oil, And Pregnancy, notes that DHA uptake is maximal during the second half of pregnancy, and is vital for brain and eye development.  It is recommended that women get 200 mg DHA daily during pregnancy, yet the average intake in the USA was estimated to be 73 mg daily.  Since many fish species are high in mercury, American guidelines recommend avoiding many types of fish during pregnancy.  Since fish oil supplements are generally molecularly distilled to remove heavy metals, they are deemed safe from mercury contamination.  However, real honest to goodness fish has some other benefits that fish oil does not - iodine, selenium, and Vitamin D. 

The editorial also critiques the Bayley scores used to measure the toddler's cognition, saying Bayley scores are not extremely sensitive, and also didn't show higher cortical differences that are better measured at 4 years of age or later (4).  In the DINO trial (3), DHA supplementation for infants showed benefit for kids at older ages but not in infancy, and the most benefit was found for preterm infants, who seem to miss out on big-time third trimester transfer of DHA. 

The conclusion of the editorial:  "Fish oil supplements are safe, well tolerated, and reduce risks for early preterm birth, which is associated with poor neurocognitive outcomes and maternal depression. Whether fish consumption during pregnancy will confer similar or perhaps even greater benefits for mothers and their children requires more investigation, including large randomized trials such as the DOMInO trial. For now, pregnant women should take care to get the recommended intake of 200 mg/d of DHA,2 either by including low-mercury, high-DHA fish in their diets or by taking a daily n-3 PUFA supplement."

What do you think would happen if omega 6 PUFAs were reduced to 4% or less of calories?  Or if pregnant mothers enjoyed a real food paleolithic-style diet?  I'm sure there's an epidemiologist out there who could use her computer to add up iodine, chromium, selenium, fish oil, magnesium, protein, etc.  A Real Food number.  That's what we need. 


  1. A therapeutic dose is more than 3000 mg. I don't think they were giving the mothers enough fish oil to make this a worthwhile study.

  2. hi Jake - the researchers powered the study to detect a 7-8% reduction in incidence of postpartum depression which was seen in the epidemiological data. In addition, those epidemiological studies estimated the fish eaters consumed approximately 1000 mg DHA daily, and Dutch studies suggest that non-habitual fish eaters get the 73mg daily. I'm not sure where 800mg came from, other than it was the amount in three capsules of fish oil. But one would think 800mg would be way better than 73mg, and if fish oil alone is the holy grail for curing what ails the brain, it should make a difference. In addition, there was a study of depression and omega3s, where 1g daily helped, but 2g or 4g was no better than 1g. (I could have sworn it was DHA, but I have to look it up specifically, which I don't have time for just now!)

  3. I saw a blurb out this study in the WSJ, where they concluded that the fish oil did not seem worth taking to improve infant brain development, and had the same reaction that Jake did. 800 mg is laughable as a dosage for a pregnant woman on the SAD.

  4. I noticed that this study began only at 21 weeks gestation. I would like to see something looking into the cognitive development of babies whose mothers took fish oil starting as soon as they discovered they were pregnant, or even pre-conception. I wonder if that might make more of a difference for fetal development.

  5. I thought the dose was 1200 mg of DHA with the corresponding amount of epa --- effective for mild to moderate depression. About 6 capsules from Whole Food. Big study by Canadians with over 4,000 participants. Anyone else know about this?


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