By Amy Norton
New York - Expectant mothers who eat enough omega-3 fats late in pregnancy may give their babies a brain-power boost, a new study suggests.
Researchers found that among 109 Inuit infants they followed, those whose umbilical-cord blood was higher in docosahexaenoic acid, an omega-3 acid, at birth did better in tests of infant brain and eye development at the ages of six and 11 months.
DHA is one of the major omega-3 fatty acids found in oily fish like salmon, sardines and tuna. Because of the fat's vital role in brain development, experts have recommended that pregnant women get an average of 300 milligrams of DHA daily.
The new findings, reported in the Journal of Pediatrics, highlight the particular importance of DHA in the mothers' diet during the third trimester, when foetal brain development accelerates.
The level of DHA in newborns' cord blood was closely related to the DHA concentrations in their mothers' blood at the time of delivery. "This study adds to a growing body of evidence regarding the importance of DHA for third-trimester foetal brain development," lead researcher Dr Joseph L. Jacobson, of Wayne State University in Detroit, told reporters.
Americans' diets are typically low in DHA, he noted, and this line of research suggests that boosting pregnant women's intake "is likely to be beneficial".
The Inuits in this study were from the northern tip of Quebec. Their traditional diet is rich in fish, but many Inuit people have adopted a more Western style of eating; as a result, mothers' DHA levels at the time they gave birth ranged from the low levels typically seen in the United States and southern Canada to relatively high concentrations.
When the babies were six months old, they were given standard tests of visual acuity and memory. The researchers found that higher cord-blood DHA at birth was linked to better performance on these tests.
The same was true when the babies were given tests of cognitive and motor development at the age of 11 months.
There was no correlation, however, between the infants' test performance and DHA from breast milk. It's likely, according to Jacobson's team, that mothers' third-trimester DHA intake is more important than babies' consumption of breast-feeding because of the "critical third trimester brain growth spurt".
Besides fish, such as tuna and salmon, other DHA sources include fish oil supplements and algae-derived DHA, which is included in some prenatal vitamins.
Pregnant and breast-feeding women are advised to avoid some fish, however, due to potentially high levels of mercury. These include shark, swordfish, king mackerel and tile fish.
According to Jacobson, "it's always a good idea" for pregnant women who want to try fish oil capsules, or any supplement, to speak with their obstetrician first.