Omega-3 polyunsaturated fatty acids (PUFAs) may be able to attenuate the immune response in a neonate and subsequently affect allergy status. This systematic review compared omega-3 PUFA to placebo during pregnancy and/or lactation on allergic disease in childhood. Based on data from 5 randomized controlled trials, supplementation during lactation did not prevent allergy. However, supplementation during pregnancy did reduce the prevalence of a positive egg skin prick test suggesting egg allergy, as well as reducing cord blood interleukin-13 levels. Thus, supplementation of omega-3 PUFAs during pregnancy is beneficial as it decreases childhood asthma and response to the egg skin prick test.
Klemens, C., D. Berman, and E. Mozurkewich, The effect of perinatal omega-3 fatty acid supplementation on inflammatory markers and allergic diseases: a systematic review*. BJOG, 2011. 118(8): p. 916-25.