Question: Supplementation with which substance during pregnancy has been shown to reduce the risk of persistent wheezing or asthma and lower respiratory tract infections in offspring?
Answer: The cited reference reports on a randomized trial involving over 700 pregnant women at 24 weeks of gestation who received 2.4 grams of n-3 long-chain polyunsaturated fatty acids (LCPUFAs) (fish oil). This study concluded “Supplementation with n-3 LCPUFA 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 approximately 7 percentage points, or one third.” (Bisgaard H et al. Fish oil-derived fatty acids in pregnancy and wheeze and asthma in offspring. 2016 NEJM 375(26): 2530-2539).
N.B. An editorial regarding this study stated “Although these results are highly promising note of caution is warranted. The dose of EPA plus DHA provided in this trial (2.4 grams per day) was approximately 15 to 25 times as high as the average U.S. intake from foods. Before these findings can be applied to clinical practice, it is imperative to ensure that this dose had no adverse effects on behavior, cognition or other long-term outcomes.”