Being born premature is fraught with complications: in addition to their underdeveloped lungs and digestive systems, which make breathing and blood-sugar regulation difficult, many preemies also suffer long-term consequences in brain development. But researchers report that there may be a way to make up for some of that cognitive deficit: taking an over-the-counter supplement.
Reporting in the Journal of the American Medical Association, Maria Makrides and her colleagues at the Women's and Childrens' Hospital in Adelaide, Australia, found that supplementing premature baby girls' diets with omega-3 fatty acids in the first few days after birth improved their performance on cognitive tests 18 months later. The same benefit was not seen in baby boys, however, possibly because premature girls and boys simply develop at different rates, the researchers speculate. (See the year in medicine 2008.)
Many nutrients vital to fetal development, including omega-3s, are delivered during the third trimester, and when premature babies miss this critical period in utero, doctors believe they may need to make up for it through either the breast milk or formula they are fed after birth. Earlier studies have shown that about 1% of a baby's total third-trimester fatty-acid intake comes from omega-3s, but by comparison, only about 0.2% to 0.35% of the total fatty acids in breast milk and infant formulas come from omega-3s. So, it makes sense that supplementing preemies' diets with omega-3 fatty acids, the same brain-boosting oils found in deep-ocean fish such as tuna and salmon, would improve their scores on cognitive tests.
Makrides asked 272 nursing moms who had given birth prematurely to take six omega-3 capsules a day, to mimic the 1% ratio that full-term babies receive in their final months in the womb. A control group of 273 similar moms took six capsules of soy, a placebo. Overall, the two groups showed no differences in cognitive tests 18 months later, but when Makrides looked at the data by gender, she found that girls getting the omega-3 supplemented breast milk did slightly better than girls receiving regular milk. The smallest premature babies also showed more benefit from the omega-3s than heavier preemies.
But are these findings reason enough to ask mothers of premature girls to start popping fish-oil capsules? Probably not, says Dr. David Adamkin, director of neonatal medicine at University of Louisville. "This study looks at giving babies nutrients that we know they don't get enough of in utero because they are born too early," he says. "While an 18-month follow up is okay, an eight-year follow up is going to be much better. We need more time to see if these differences are really going to persist."
Makrides plans to continue following the 657 premature babies in the study for another seven years, periodically testing their mental function. "Studies suggest that girls and boys who are born prematurely are indeed different in brain development," she says. "They actually don't have equivalent scores until about seven years of age. We will continue to follow these children until they are seven and we will be able to work out whether the effects seen at 18 months persist, and whether they are permanent."
In the meantime, U.S. experts are still waiting for additional data to support the benefits of early omega-3 supplementation. "This study suggests that there is some programming function going on, that specific nutrients given at specific times may be very important to get the best neurodevelopmental outcomes," says Adamkin. "We are trying to learn what those nutrients are and what those critical windows are."
It's also worth remembering, says Adamkin, that some fish-oil capsules may contain mercury, which can actually deter brain development in children, and some studies have shown that too much omega-3 can retard kids' language development. It's also not clear from the current study exactly how much additional omega-3 is actually needed to see a benefit; while Makrides's study targeted the amounts a third-trimester fetus might receive, it's possible that the same brain benefits may accrue with less supplementation, or that more benefits may be gained by increasing the dose.
Even without answers to these questions, the neonatal unit in the Women's and Children's Hospital in Adelaide is already changing its policies, and giving mothers of premature girls omega-3 capsules through the hospital pharmacy. Makrides says that fish-oil capsules in Australia are stripped of mercury or pesticide residues by law, and so far, taking omega-3 does not seem to have produced any side effects, in either mother or child.
The new mothers in Makrides' study have been eager to comply with the fish-oil supplementation program. "Women of premature babies tend to be more motivated than the general public to take action because they have a sick, premature baby, and anything they feel they can do to help this baby, they will do," she says. And that includes taking a half dozen fish oil capsules.