Supplementation with omega-3 fatty acids may not improve maternal depression

The use of docosahexaenoic acid fish oil capsules may not decrease depression in mothers after birth nor improve cognitive or language development of young children, suggests a new Australian study.

In the randomized controlled trial, 2399 pregnant women were randomly assigned to receive docosahexaenoic acid (DHA)–rich fish oil capsules (providing 800 mg/day of DHA and 100 mg/day of eicosapentaenoic acid, EPA) or vegetable oil capsules without DHA (placebo) from less than 21 weeks’ pregnancy to birth (1). The levels of depressive symptoms were measured in the women at 6 weeks or 6 months after birth. In addition, the cognitive and language development of their children was assessed at 18 months. The results showed that 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 the mothers nor did it improve cognitive and language development in their offspring during early childhood.

Experts criticized that the trial did not measure the DHA status of the mothers, at the beginning of pregnancy or when they were evaluated for depression, and of the infants, at 18 months. Without measurements of DHA status, it would be difficult to draw conclusions from the study, which certainly should not provide definitive advice to consumers. Essentially, DHA status would need to be adequate throughout pregnancy for women and their infants to receive the many health benefits.

In an editorial note, researchers commented that fish oil supplements have shown to reduce risks for early preterm birth, which is associated with poor cognitive outcomes and maternal depression (2). In addition, they have been proven safe and well tolerated. Whether fish consumption during pregnancy will confer similar or perhaps even greater benefits for mothers and their children would require more investigation, including large randomized trials. For now, they concluded, pregnant women should take care to get the recommended intake of 200 mg/day of DHA, either by including low-mercury, high-DHA fish in their diets or by taking a daily omega-3 fatty acids supplement (3).

Studies have shown that the status of omega-3 fatty acids is critical during pregnancy. Docosahexaenoic acid (DHA) is a necessary structural component of the brain and retina, and DHA uptake into these tissues is maximal during the second half of gestation and infancy. Concern exists that infants whose mothers consume little fish or who are born preterm may not receive enough DHA during the critical early months of brain development.

1. Makrides M. et al. Effect of DHA supplementation during pregnancy on maternal depression and neurodevelopment of young children. JAMA. 2010; 304(15):1675–1683.
2. Oken E. and Belfort M. B. Fish, Fish Oil, and Pregnancy. JAMA. 2010; 304(15):1717–1718.
3. Koletzko B. et al. Dietary fat intakes for pregnant and lactating women. Br J Nutr. 2007; 98(5): 873–877.