Fish Oil For Childhood Asthma Prevention?

The New England Journal of Medicine has published findings promising to the lowering of asthma risk in children. Over 700 pregnant women entering their third trimester were randomized to receive daily supplements containing either 2.4 g of fish oil or a placebo in the form of olive oil, up until one week after delivery.

The fish oil pill contained the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The main assessment on the effect of the fish oil supplementation was for the babies’ risk of persistent wheeze and asthma.

The children formed the Copenhagen Prospective Studies on Asthma in Childhood 2010 cohort and were followed prospectively with extensive clinical phenotyping. Neither the investigators nor the participants were aware of group assignments during follow-up for the first three years of the children’s lives. There was then also a two-year follow-up period during which only the investigators were unaware of group assignments.

A total of 695 children were included in the trial. The risk of persistent wheeze or asthma in the treatment group was 16.9%, versus 23.7% in the control group. Among women with the lowest blood levels of EPA and DHA at the time of the initial randomization, fish oil supplementation cut the risk for these two primary outcomes in half.

At the same time, it appears that reduced intake of n−3 long-chain polyunsaturated fatty acids may be a contributing factor to persistent wheezing disorders, the prevalence of which are increasing. Supplementation also reduced the risk of infections of the lower respiratory tract in offspring by roughly seven percentage points, or one third.

In an editorial accompanying the findings, NEJM  notes that we should proceed with caution. While referring to the findings as "highly promising," the author notes that it's "imperative to ensure that [the high omega-3 dose used] had no adverse effects on behavior, cognition, or other long-term outcomes."

NEJM, 2016, Vol. 375, pp. 2530-2539, http://www.nejm.org/doi/full/10.1056/NEJMoa1503734?query=pfw&jwd

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