Study Finds Fish Oil No Help to Babies
By PAM BELLUCK
Published: October 19, 2010
Many women take fish oil supplements during pregnancy, encouraged by obstetricians, marketing campaigns or the popular view that a key fish oil ingredient ― docosahexaenoic acid, or DHA ― is beneficial to a baby’s cognitive development.
But a large study published Tuesday in The Journal of the American Medical Association suggests that the DHA supplements taken by pregnant women show no clear cognitive benefit to their babies. The study also found no evidence that DHA can reduce postpartum depression, except perhaps for women already at high risk for it.
Some previous studies have suggested that DHA, an omega-3 fatty acid in fish oil, can aid in a baby’s brain development if taken during pregnancy. But many of those studies were small or observed women already taking fish oil, who might be more health-conscious. The new study, with more than 2,000 participants, was a clinical trial in which women received either fish oil with DHA or a placebo (vegetable oil).
“It’s puzzling because observational studies have shown benefits,” said Dr. Emily Oken, an associate professor in population medicine at Harvard Medical School, who wrote an editorial accompanying the study. But not every expert was surprised.
“I think a lot of us have been skeptical that something as easy as taking a DHA supplement would improve neurologic development,” said Dr. William Barth Jr., chief of maternal-fetal medicine at Massachusetts General Hospital. “I wish it were so simple, that there was a pill we could take to make our children smarter.”
Dr. Barth said more research was needed, but for now, “I think the market is running way out in front of the science.”
Scientists agree that DHA, naturally transmitted to a fetus through the placenta during the last half of pregnancy, is important, probably to visual and brain development. Several studies indicate that babies born prematurely receive too little DHA, and some studies have found that premature babies fed DHA after birth show better cognitive performance or visual coordination later on than preemies who aren’t given DHA.
But the new study, which mainly assessed full-term babies, found no cognitive difference at 18 months whether mothers received DHA supplements or placebos. The lead researcher, Dr. Maria Makrides of the University of Adelaide in Australia, said this suggests that full-term babies already get enough DHA in the womb, and that “there’s no extra boost” from getting more.
Nonetheless, several experts said they would continue to support taking DHA in pregnancy, especially since it is safe and apparently has few downsides. They cited a smaller 2003 Norwegian study that found I.Q. increases at age 4, although no cognitive benefit was seen in infants or 7-year-olds.
That study’s lead author, Dr. Ingrid Helland of Oslo University Hospital, said that perhaps the benefit shown at age 4 existed at 7 but was difficult to identify amid other developmental factors. She said babies in her study may have received more DHA than those in the new study because mothers, who mostly breast-fed, continued DHA supplements after giving birth. Dr. Oken said the new study may have shown no benefit in 18-month-olds because effects in infants may be “hard to measure” or “it may be that the benefit of DHA is not as important as when you’re 4.”
Dr. Makrides’s team plans assessments at 4 and 7. Dr. Jatinder Bhatia, a neonatologist heading the nutrition committee of the American Academy of Pediatrics, said that unless further studies showed no benefit as children got older, he would continue recommending DHA, now in many prenatal vitamins, to pregnant women because “I’m not convinced at this time that we should reverse course.”
Much about DHA remains unknown, and its use in supplements for children and adults ― for attention deficit disorder and Alzheimer’s disease, among others ― is being studied. One question is whether taking supplements provides the same benefit as eating DHA-rich fish, like salmon.
Some studies, including the new report, suggest DHA supplementation in pregnancy reduces the likelihood of premature birth. And the new study showed small reductions in postpartum depression in women with histories or high risk of depression. Dr. Scott Stuart, a University of Iowa psychiatry and psychology professor studying DHA’s effect on depression during pregnancy, said his pregnant patients with mild to moderate depression had improved when taking DHA while seeing a counselor. He recommends the supplement, saying, “There’s no harm that we know of at all, in contrast to many antidepressants, and it might be of some help.”
Dr. Makrides suggests specifying DHA supplements for women at risk for postpartum depression or premature birth.
“For everybody else,” she said, “it’s not necessary, I’d say.”
Effect of DHA Supplementation During Pregnancy on Maternal Depression and Neurodevelopment of Young Children
A Randomized Controlled Trial
Maria Makrides, BSc, BND, PhD; Robert A. Gibson, BSc, PhD; Andrew J. McPhee, MBBS; Lisa Yelland, BSc; Julie Quinlivan, MBBS, PhD; Philip Ryan, MBBS, BSc; and the DOMInO Investigative Team
JAMA. 2010;304(15):1675-1683. doi:10.1001/jama.2010.1507
Context Uncertainty about the benefits of dietary docosahexaenoic acid (DHA) for pregnant women and their children exists, despite international recommendations that pregnant women increase their DHA intakes.
Objective To determine whether increasing DHA during the last half of pregnancy will result in fewer women with high levels of depressive symptoms and enhance the neurodevelopmental outcome of their children.
Design, Setting, and Participants A double-blind, multicenter, randomized controlled trial (DHA to Optimize Mother Infant Outcome [DOMInO] trial) in 5 Australian maternity hospitals of 2399 women who were less than 21 weeks' gestation with singleton pregnancies and who were recruited between October 31, 2005, and January 11, 2008. Follow-up of children (n = 726) was completed December 16, 2009.
Intervention Docosahexaenoic acid--rich fish oil capsules (providing 800 mg/d of DHA) or matched vegetable oil capsules without DHA from study entry to birth.
Main Outcome Measures High levels of depressive symptoms in mothers as indicated by a score of more than 12 on the Edinburgh Postnatal Depression Scale at 6 weeks or 6 months postpartum. Cognitive and language development in children as assessed by the Bayley Scales of Infant and Toddler Development, Third Edition, at 18 months.
Results Of 2399 women enrolled, 96.7% completed the trial. The percentage of women with high levels of depressive symptoms during the first 6 months postpartum did not differ between the DHA and control groups (9.67% vs 11.19%; adjusted relative risk, 0.85; 95% confidence interval [CI], 0.70-1.02; P = .09). Mean cognitive composite scores (adjusted mean difference, 0.01; 95% CI, --1.36 to 1.37; P = .99) and mean language composite scores (adjusted mean difference, --1.42; 95% CI, --3.07 to 0.22; P = .09) of children in the DHA group did not differ from children in the control group.
Conclusion The use of DHA-rich fish oil capsules compared with vegetable oil capsules during pregnancy did not result in lower levels of postpartum depression in mothers or improved cognitive and language development in their offspring during early childhood.
Trial Registration anzctr.org.au Identifier: ACTRN12605000569606
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