DHA has become the "it" nutritional supplement for pregnant women and babies, marketed as an elixir that that will make a child bigger, stronger, smarter, healthier and more coordinated.
Now comes evidence from a study just published in Pediatrics that shows infants whose mothers took DHA supplements while pregnant did have fewer, shorter colds. But the cold-fighting benefits of DHA were pretty modest, with the DHA babies at three months having colds that were just 14 percent shorter.
At one month, the median duration of some symptoms was significantly shorter. Wheezing, for instance, lasted about three days for the DHA babies instead of five days for those whose moms got placebo. Coughing lasted about four days instead of five. But many weren't much different.
In fact, most of the evidence in favor of taking DHA, or docosahexaenoic acid, which is found in fish, nuts and algae, is modest. DHA has been shown to be good at lowering triglycerides, which contribute to cardiovascular disease, and the substance may help prevent heart disease in other ways. But although hundreds of studies on DHA supplementation have been published in the past five years, none has found strong connections between DHA supplements and children's health.
A study published last year in the JAMA, the Journal of the American Medical Association found that 800-milligram DHA supplements did nothing to prevent postpartum depression in women. The babies of the women who took DHA while pregnant showed no increase in cognitive and language skills of the children at 18 months.
Scientists have been interested by DHA and other omega-3 fatty acids because they're involved in inflammation and immune system function. There's lots of DHA in brains and eyes, suggesting that they're essential for those key organs. Indeed, researchers at Harvard Medical School recently found that women who ate lots of fish were less likely to have macular degeneration, a common cause of vision loss in old age. But that's not to say that taking DHA supplements while pregnant, or feeding it to infants, is a guaranteed brain-builder.
Emory University's Usha Ramakrishnan, senior author of the Pediatrics paper, found the previous research on DHA and its benefits for children's health wanting. "There was very little evidence" that DHA helps, Ramakrishan, a maternal and child nutrition specialist, told NPR's Allison Aubrey.
So Ramakrishnan has been studying how DHA supplements affect the pregnancies of low-income women in Mexico. Her most recent output, the Pediatrics study, found that 3-month-olds and 6-month-olds whose mothers had taken 400 milligrams of DHA daily while pregnant had shorter colds, while 1-month-olds had fewer colds.
But, she notes, at that age usually don't have many colds. And that's all they good news they could find. "We found no difference in the two groups on growth," she says. That's of a piece with other research on DHA. A review of research on DHA research by the National Library of Medicine's MedlinePlus service found "insufficient evidence" that DHA helps infant development.
Oh, in case you were wondering, Ramakrishnan's study was funded by the National Institutes of Health and the March of Dimes Foundation.