Randomized controlled trial of fish oil supplementation in pregnancy on childhood allergies

Background Diets high in n‐3 long chain polyunsaturated fatty acids (LCPUFA) may modulate the development of IgE‐mediated allergic disease and have been proposed as a possible allergy prevention strategy. The aim of this study was to determine whether n‐3 LCPUFA supplementation of pregnant women reduces IgE‐mediated allergic disease in their children. Methods Follow‐up of children (n = 706) at hereditary risk of allergic disease in the Docosahexaenoic Acid to Optimise Mother Infant Outcome randomized controlled trial. The intervention group (n = 368) was randomly allocated to receive fish oil capsules (providing 900 mg of n‐3 LCPUFA daily) from 21 weeks' gestation until birth; the control group (n = 338) received matched vegetable oil capsules without n‐3 LCPUFA. The diagnosis of allergic disease was made during medical assessments at 1 and 3 years of age. Results No differences were seen in the overall percentage of children with IgE‐mediated allergic disease in the first 3 years of life between the n‐3 LCPUFA and control groups (64/368 (17.3%) vs 76/338 (22.6%); adjusted relative risk 0.78; 95% CI 0.58–1.06; P = 0.11). Eczema was the most common allergic disease; 13.8% of children in the n‐3 LCPUFA group had eczema with sensitization compared with 19.0% in the control group (adjusted relative risk 0.75; 95% CI 0.53–1.05; P = 0.10). Conclusions Overall, n‐3 LCPUFA supplementation during pregnancy did not significantly reduce IgE‐associated allergic disease in the first 3 years of life. Further studies should examine whether the nonsignificant reductions in IgE‐associated allergies are of clinical and public health significance.