The effects of dietary supplementation with fish oil lipids on the airways response to inhaled allergen in bronchial asthma

The effects of dietary supplementation with fish oil lipids on the airways responses to allergen and neutrophil biochemistry and function have been studied in 17 atopic asthmatic subjects. Nine subjects received 18 capsules of Max-EPA (3.2 g eicosapentaenoic acid and 2.2 g docosahexaenoic acid) a day and eight subjects received identical capsules containing olive oil, for 10 wk in a double-blind fashion. There were no differences between prediet values and those observed after dietary supplementation with Max-EPA or placebo in the dose of allergen causing an acute asthmatic response as assessed by a 35% fall in specific airways conductance (PD₃₅), the extinction dose of allergen on skin prick testing, the histamine PD₃₅, or the total serum IgE concentrations. Twelve of the 17 subjects developed late asthmatic responses after allergen challenge prediet. Six of these subjects received Max-EPA, and six received placebo capsules. As compared to prediet values, the magnitude of the allergen-induced late asthmatic responses was significantly attenuated from 2 to 7 h after allergen challenge following dietary supplementation with Max-EPA (p < 0.005) but not with placebo. The attenuation of the late response was not accompanied by any significant change in the clinical severity of disease as assessed by diurnal peak expiratory flow rates, symptom scores, or bronchodilator drug usage. As compared to prediet values, there was a 10-fold increase in neutrophil EPA content, neutrophil chemotactic responses to formyl-methionyl-leucyl-phenylalanine were depressed by approximately 50%, and there was a mean 47% inhibition of leukotriene B₄ generation by neutrophils stimulated by the calcium ionophore after dietary supplementation with Max-EPA but not after placebo.