There is increasing evidence to suggest that dietary lipids, especially long-chain polyunsaturated fatty acids may play a role in regulating immune function and contribute to the development and severity of symptoms of atopic disease.^{23, 28}

Ratio between omega-6 and omega-3 fatty acids

In Western diets, consumption of saturated fatty acids has decreased with the increased use of margarine and vegetable oils, which are rich in omega-6 fatty acids.^{24-26, 44} Consumption of omega-3 fatty acids has decreased.

These dietary changes have resulted in a high ratio of omega-6 fatty acids to omega-3 fatty acids. Omega-6 fatty acids promote inflammation while omega-3 fatty acids appear to inhibit allergic immune responses.^{21, 45} The altered ratio between them may therefore be a factor in the pathogenesis of inflammatory and autoimmune diseases.⁴⁶

Omega-3 fatty acid supplementation

While there is little evidence to support the use of omega-3 supplementation in asthma management,^47-48 case-control data have suggested that reduced intake of fish in the diet is a risk factor for asthma.⁴⁹ As this would constitute a modifiable risk factor, the effectiveness of modifying dietary omega-3 fatty acids during pregnancy and infancy are under investigation.^{20-22, 34}

Increasing prenatal and postnatal intake of omega-3 fatty acid through dietary supplements (eg capsules) may reduce the prevalence of wheeze in the first 3 years of life.^{20, 34 Level II Evidence}

Content Updated March 2005