Researchers from the University of Western Australia based their findings on 98 pregnant women, who were either given daily supplements of fish oil or olive oil from 20 weeks of pregnancy until the birth of their babies.
"Given the scarcity of data to support the efficacy of fish oil supplementation during pregnancy, our data have potentially important role in informing on the effects of fish oil supplementation on early postnatal infant development," wrote the researchers, led by Susan Prescott, in the Archives of Disease in Childhood (Fetal and Neonatal Edition).
The small study only included women who did not regularly consume more than two weekly portions of fish and were non-smokers. Only 83 mother completed the study.
Starting at 20 weeks' gestation until birth, the pregnant women were assigned to receive either a daily dose of 4 grams of fish oil (Ocean Nutrition, Canada, providing 1.1 grams of eicosapentaenoic acid (EPA) and 2.2 grams of docosahexaenoic acid (DHA)) or the same dose of olive oil, providing 2.7 grams of n-9 oleic acid).
Once the kids had reached two and a half years of age, the cognitive performance of 72 children was assessed (33 in the fish oil group and 39 in the olive oil group) using a battery of tests, including the Griffiths Mental Development Scales (GMDS), the Peabody Picture Vocabulary Test (PPVT), and the Child Behaviour Checklist (CBCL).
While no significant differences were observed in overall language skills and growth between the two groups of children, the researchers report that the children whose mothers had taken fish oil supplements had higher scores for receptive language (comprehension), average phrase length, and vocabulary.
They also report that high levels of omega-3 fatty acid in cord blood were strongly associated with good hand-eye coordination, while low levels of omega 6 fatty acids, found in many vegetable oils, were not.
"We found that cord erythrocyte phospholipid n-3 long-chain polyunsaturated fatty acid (LC PUFA) levels positively correlated and n-6 levels negatively correlated with eye and hand coordination, a finding that, to the best of our knowledge, has not been reported previously," said the researchers.
The study does have several limitations, said the authors, most notably the small size of the study population.
"These preliminary data indicate that supplementation with a relatively high-dose fish oil during the last 20 weeks of pregnancy is not only safe but also seems to have potential; beneficial effects that need to be explored further," said the researchers.
"In conclusion, our findings are important in tackling concerns that a relatively selective supplementation (with n-3 PUFA but not n-6 PUFA) could have detrimental effects by displacing other essential fatty acids."
The research adds to the healthy reputation of omega-3 fatty acids that is seeping into consumer consciousness, based largely on evidence that it can aid cognitive function, may help protect the heart against cardiovascular disease, and could reduce the risk of certain cancers.
Such reports have seen the number of omega-3 enriched or fortified products on the market increase.
However, fears about dwindling fish stocks and the presence of pollutants, such as methyl mercury, dioxins, and polychlorinated biphenols (PCBs), have pushed some academia and industry to start producing omega-3s from alternative sources, such as algae extraction or transgenic plant sources. Most extracted fish oils are molecularly distilled and steam deodorised to remove contaminants.
According to Frost and Sullivan, the European omega-3 market was worth around €160m (£108m) in 2004, and is expected to grow at rates of 8 per cent on average to 2010.
Source: Archives of Disease in Childhood (Fetal and Neonatal Edition) Published on-line ahead of print, doi: 10.1136/adc.2006.099085 "Cognitive assessment of children at age 2.5 years after maternal fish oil supplementation in pregnancy: a randomized controlled trial" Authors: J.A. Dunstan, K. Simmer, G. Dixon, S.L. Prescott