Fish oil in infancy protects against food allergy in Iceland—Results from a birth cohort study

BACKGROUND: Consumption of oily fish or fish oil during pregnancy, lactation and infancy has been linked to a reduction in the development of allergic diseases in childhood. METHODS: In an observational study, Icelandic children (n = 1304) were prospectively followed from birth to 2.5 years with detailed questionnaires administered at birth and at 1 and 2 years of age, including questions about fish oil supplementation. Children with suspected food allergy were invited for physical examinations, allergic sensitization tests, and a double‐blind, placebo‐controlled food challenge if the allergy testing or clinical history indicated food allergy. The study investigated the development of sensitization to food and confirmed food allergy according to age and frequency of postnatal fish oil supplementation using proportional hazards modelling. RESULTS: The incidence of diagnosed food sensitization was significantly lower in children who received regular fish oil supplementation (relative risk: 0.51, 95% confidence interval: 0.32‐0.82). The incidence of challenge‐confirmed food allergy was also reduced, although not statistically significant (0.57, 0.30‐1.12). Children who began to receive fish oil in their first half year of life were significantly more protected than those who began later (P = .045 for sensitization, P = .018 for allergy). Indicators of allergy severity decreased with increased fish oil consumption (P = .013). Adjusting for parent education and allergic family history did not change the results. CONCLUSION: Postnatal fish oil consumption is associated with decreased food sensitization and food allergies in infants and may provide an intervention strategy for allergy prevention.