Major study of fish oil finds no benefit

An Australian study has found no marked benefits on mums or their babies when the mums took fish oil during their pregnancy. Photo / Thinkstock

SYDNEY - It's promoted as beneficial to mum and baby, but a major Australian study has found no noticeable effect among women who took fish oil capsules during pregnancy.

The research, conducted over five years, looked at 2400 pregnant women who were given fish oil capsules or an identical vegetable oil placebo during the latter phase of their pregnancy.

The outcome was the same for both groups despite the benefits of fish oil being widely promoted on the internet and by some medical professionals and pregnancy health guidelines.

"There was no significant difference in either the incidence of post-natal depression (for mums) or neuro developmental outcomes of their children," said Professor Maria Makrides from the University of Adelaide.

"These results show that recommendations to increase omega 3 fatty acids in pregnancy are being made without sound evidence."

Women with a history of depression were more likely to experience post natal depression as a new mum, but there was no benefit seen from those who took fish oil compared to the vegetable oil placebo.

Similarly, 700 children from the study group were assessed for cognitive and language development at 18 months of age and there were no marked differences.

Prof Makrides said earlier research from the US and Europe which suggested benefits from eating fish during pregnancy could be skewed by social factors, as families who were more affluent could afford to eat more fish and seafood.

"Despite the paucity of hard evidence, women are being recommended to increase their intake of fish oil fats in pregnancy, and the nutritional supplement industry is successfully marketing products with fish oil, claiming they optimise brain function in both mother and infant," she said.

"Before omega 3 supplementation in pregnancy becomes widespread, it is important to establish not only any benefits, but also any risks to mother or child."

Prof Makrides is Professor of Human Nutrition at the University of Adelaide and Deputy Director of the Women's and Children's Health Research Institute.

Her research, funded by a $1.6 million National Health and Medical Research Centre (NHMRC) grant, is published in the Journal of the American Medical Association.

It follows the release of a US study, published this month, in which scientists unexpectedly found a negative effect of fish oil.

One fatty acid - docosahexaenoic acid (DHA) - was found to promote cancer growth in mice that were prone to bowel diseases.

"We hypothesised that feeding fish oil enriched with DHA to mice would decrease the cancer risk. We actually found the opposite," said Dr Jenifer Fenton, from Michigan State University.

"Our findings support a growing body of literature implicating harmful effects of high doses of fish oil consumption in relation to certain diseases."

- AAP