Does prenatal fish oil reduce asthma in offspring?
Results of a prospective study suggest that taking fish oil during the third trimester can lower the risk of persistent wheeze or asthma and infections in offspring. The findings, published in The New England Journal of Medicine, were reported by a team of Danish, Canadian, and US investigators.
A total of 695 children from the Copenhagen Prospective Studies on Asthma in Childhood2010 cohort were followed prospectively with extensive clinical phenotyping. They were the offspring of 736 pregnant women randomly assigned to receive 2.5 g of n-3 LCPUFA (fish oil) or placebo (olive oil) per day beginning at 24 weeks’ gestation.
For the first 3 years of the children’s lives, neither the investigators nor the participants were aware of the group assignments. Only the investigators were unaware of the randomization assignments during the subsequent 2-year follow-up period.
In the treatment group, risk of persistent wheeze or asthma was 16.9% versus 23.7% in the control group (hazard ratio [HR], 0.69; 95% confidence interval [CI], 0.49 to 0.97; P=0.035 for a relative risk reduction of 30.7%. Analysis of secondary end points—lower respiratory tract infections, asthma exacerbations, eczema, and allergic sensitization—showed that the fish oil supplementation was associated with a reduce risk of lower respiratory tract infection (31.7% to 39.1%; HR 0.75, 95% CI 0.58 to 0.98; P=0.033). There was no statistically significant association between intake of fish oil and the other secondary end points.
Supplementation with fish oil in the third trimester, the investigators concluded, reduced absolute risk of persistent wheeze or asthma and infections of the lower respiratory tract in offspring by 7% or one-third. The authors of an accompanying editorial posited that a precision medicine approach may be better than widespread use of fish oil because the results were largely driven by women with the lowest baseline levels of EPA and DHA, particularly those with a variant gene for fatty acid desaturase. Because the very high doses of EPA and DHA used in the study also may be associated with other adverse effects, long-term follow-up and study of lower doses are needed.