Preterm infant girls who received a high amount of dietary docosahexaenoic acid (DHA; an omega-3 fatty acid) had higher measures of neurodevelopment than preterm girls who received a standard amount of DHA, but this effect was not seen among preterm boys, according to a study in the January 14 issue of JAMA: The Journal Of the American Medical Association.
Infants born before 33 weeks' gestation are at high risk of developmental disorders and learning disabilities. An inadequate nutrient supply during the newborn period is believed to contribute to this poor developmental outcome, according to background information in the article. DHA deficiency is hypothesized to result in poor neurodevelopmental outcomes in preterm infants, but uncertainty exists about the benefit of dietary DHA.
Maria Makrides, B.Sc., B.N.D., Ph.D., of Women's and Children's Hospital and Flinders Medical Centre, Adelaide, Australia and colleagues conducted a randomized controlled trial to determine the effect of high-dose dietary DHA on neurological outcomes in preterm infants. The study included infants born at less than 33 weeks' gestation from five Australian hospitals. Of the 657 infants enrolled, 93.5 percent completed the 18-month follow-up.
The infants were randomized to high-DHA (approximately 1 percent total fatty acids) compared with standard DHA (approximately 0.3 percent total fatty acids) from day 2 to 4 of life until the infants reached their expected date of delivery. The infants received DHA from either breast milk or infant formula. Lactating mothers allocated to the high-DHA group were asked to consume six 500-mg DHA-rich tuna oil capsules per day to achieve a high breast milk DHA concentration. If supplementary formula was required, infants were given a high-DHA preterm formula. Mothers with infants allocated to the standard-DHA group were asked to consume six 500-mg placebo soy oil capsules that did not change the fat content or fatty acid composition of their milk.
To measure neurological development, the researchers used the Bayley Mental Development Index (MDI), which evaluates memory, problem solving, early number concepts and language. They found that the average MDI score did not differ between the high-DHA and standard-DHA groups, but that the MDI score among girls fed the high-DHA diet was significantly higher than among girls fed the standard-DHA diet, while the MDI score among boys did not differ between groups.
“The lack of responsiveness of boys to the intervention is puzzling, and the reasons are unclear …,” the authors write.