Prenatal Fish Oil May Trim Asthma Risks in Children

The risk of asthma may be reduced in the children of pregnant women who take fish oil supplements, according to a new study.

Supplementation with n−3 long-chain polyunsaturated fatty acids in the third trimester of pregnancy reduced the absolute risk of persistent wheeze or asthma and infections of the lower respiratory tract in offspring by about one-third, stated the authors, led by Hans Bisgaard, MD, DMSc, of the University of Copenhagen, Denmark.

Studies show reduced intake of fish oils may contribute to the increasing prevalence of wheezing disorders, the researchers noted.

They randomly assigned 736 pregnant women at 24 weeks of gestation to receive 2.4 g of fish oil or placebo (olive oil) per day. Their children formed the Copenhagen Prospective Studies on Asthma in Childhood 2010 cohort. A total of 695 children were included in the trial, and virtually all (95%) completed the 3-year, double-blind follow-up period.

The researchers recorded when asthma, allergy, and eczema developed in the children. They also collected symptom diaries from the parents. The primary end point was “persistent wheeze” or asthma.

The risk of persistent wheeze or asthma in the treatment group was 16.9%, compared with 23.7% in the control group, corresponding to a relative reduction of 30.7%.

Prespecified subgroup analyses suggested that the effect was strongest in the children of women who had lower pretreatment serum levels of the fatty acids eicosapentaenoic acid and docosahexaenoic acid. The risk of persistent wheeze or asthma was 19.3% in the treatment group versus 21.5% in the control group, not a statistically significant difference. However, when the offspring of the mothers in the lowest third for plasma fatty acid levels were examined, persistent wheeze or asthma developed in 17.5% of the treatment group compared with 34.1% in the control group. At age 5 years, the hazard ratio (0.68) still favored the treatment group.

The researchers calculated that the number needed to treat to prevent 1 case of persistent wheeze or asthma was 14.6 among all children but only 5.6 among women in the lowest third of baseline fatty acid levels.

Secondary analyses showed that fish oil supplementation was associated with a reduced risk of infections of the lower respiratory tract, but there was no statistically significant association between supplementation and asthma exacerbations, eczema, or allergic sensitization.

The researchers published their results in the December 29, 2016 New England Journal of Medicine.

In an accompanying editorial, Christopher E. Ramsden, MD, of the National Institute of Alcohol Abuse and Alcoholism, stated, “Asthma and lower respiratory infections are leading causes of morbidity and mortality in pediatric populations. Thus, having low-cost, effective, safe options for prevention could have important implications for both clinical practice and public health.” He noted that the protective effects of the supplementation were seen even as far out as in children aged 5 years.

Dr Ramsden pointed out that the fish oil supplement amounts used in the study were at least 15 times greater than the average daily intake derived from the typical US diet.