By Amanda Gardner

MONDAY, August 1, 2011 ( — Pregnant women who consume plenty of omega-3 fatty acids from supplements or natural sources such as salmon may be helping to fortify the immune system of their babies, a new study in the journal Pediatrics suggests.

Infants whose mothers took supplements containing docosahexaenoic acid, or DHA—one of the two main ingredients in fish oil—had fewer days with cold symptoms during their first six months of life than infants whose mothers received a placebo, the study found.

Newborns in the DHA group were also slightly less likely to come down with a cold in the first place.

Though promising, the new findings are preliminary. And the researchers say it's too soon for doctors to advise moms-to-be to take DHA supplements as an essential part of their pregnancy diet.

"Recommending women to take a dose of up to 400 milligrams of DHA during pregnancy would be safe, [but] how much of a benefit there is we don't know yet," says Usha Ramakrishnan, PhD, the lead author of the study and an associate professor of global health at Emory University's Rollins School of Public Health, in Atlanta.

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    Omega-3 fatty acids, which are thought to have anti-inflammatory effects, have long been touted as a natural way to fight a range of ailments, from heart disease to depression.

    "There is research to suggest that the fatty acid composition of many of our cells—particularly the immune cells—affect their function," Ramakrishnan says.

    Previous research has suggested that DHA supplements can improve respiratory health and overall immune function in babies and children, but this is just the second study to explore whether exposure to DHA in the womb might have similar effects.

    Ramakrishnan and her colleagues randomly assigned more than 800 pregnant women in Mexico to receive either 400 milligrams of DHA per day or a placebo. (The researchers used DHA supplements derived from algae rather than fish, because the distinctive taste of fish oil would have made it harder to disguise which type of pill the women were receiving.) The women began taking the pills during their second trimester and continued to do so until they gave birth.

    Then, at three separate points over the next six months, the researchers surveyed the mothers about whether their child had experienced cold symptoms such as coughing, nasal congestion, and fever in the previous 15 days—and if so, how long the symptoms lasted.

    At all three time points, the duration of cold symptoms tended to be shorter in the children whose mothers had taken the DHA supplements. And at the one-month mark, the DHA babies had 24% lower odds of having had any cold symptoms.

    Ramakrishnan says the findings can likely be extrapolated to the Hispanic population in the U.S. and most probably to other ethnic and racial groups, but more research will be needed to confirm the results.