Study: Fish Oil Doesn't Affect Postpartum Depression
Nor Does Fish Oil Boost Children's Learning
DHA and Depression: A Closer Look continued...
At six months after birth, the percent of women with high levels of depressive symptoms did not differ much between the two groups, Makrides found. While 9.6% of those taking DHA had high levels of depression, 11% of the mothers taking the vegetable oil capsules did.
In the subgroup of women who had a previous history of depression, they found a 3% or 4% reduction in symptoms, she says. "It may be that these women will benefit from supplementation, but other studies are needed to confirm this," she says.
The mothers taking DHA did have fewer preterm births before 34 weeks' gestation. While 1% of the DHA mothers had a baby before 34 weeks, 2.25% of those in the vegetable oil group did. However, more of the DHA mothers went over the due date enough to require interventions such as induced labor or cesarean deliveries.
When tested at 18 months, the average cognitive and language scores of the children did not differ between groups.
It could be that a longer-term assessment is needed, Makrides says. "We are already planning to assess all the children again at 4 years."
Makrides reports serving on the scientific advisory boards of Nestle, Fonterra (a dairy company), and Nutricia (a medical nutrition company).
DHA and Effects: Industry Speaks
The study findings are inconsistent with those of many previous studies, says Duffy MacKay, ND, vice-president of scientific and regulatory affairs for the Council for Responsible Nutrition in Washington, D.C., a trade association representing manufacturers and ingredient suppliers of dietary supplements.
He also sees some weaknesses in the study. "The timeliness of the intervention may be off," he says, explaining that starting the supplements earlier than 21 weeks may have been better.
Some researchers question whether the most valuable nutrient for depression is DHA or another fatty acid, EPA. So knowing the levels of both EPA and DHA in mothers and infants would have been good information, he says.
Makrides' plan to assess the children later is a good one, he says.
His advice on DHA and EPA? "Make sure you get these nutrients, whether getting them from food or supplements."