A causal link between increased intake of omega-6 (n-6)
polyunsaturated fatty acids (PUFAs) and increased incidence of allergic disease has been suggested. This is supported by biologically plausible mechanisms, related to the roles of
eicosanoid mediators produced from the n-6 PUFA
arachidonic acid. Fish and
fish oils are sources of long chain omega-3 (n-3) PUFAs. These
fatty acids act to oppose the actions of n-6 PUFAs particularly with regard to
eicosanoid synthesis. Thus, n-3 PUFAs may protect against allergic sensitisation and allergic manifestations. Epidemiological studies investigating the association between maternal fish intake during pregnancy and allergic outcomes in infants/children of those pregnancies suggest protective associations, but the findings are inconsistent.
Fish oil provision to pregnant women is associated with immunologic changes in cord blood. Studies performed to date indicate that provision of
fish oil during pregnancy may reduce sensitisation to common food
allergens and reduce prevalence and severity of
atopic eczema in the first year of life, with a possible persistence until adolescence. A recent study reported that
fish oil consumption in pregnancy reduces persistent wheeze and
asthma in the offspring at ages 3 to 5 years. Eating oily fish or
fish oil supplementation in pregnancy may be a strategy to prevent infant and childhood allergic disease.