Background It has been hypothesized that increased consumption of n-6 polyunsaturated fatty acids and decreased consumption of n-3 polyunsaturated fatty acids have contributed to the recent increased prevalence of asthma.
Objectives The present cross-sectional study examined the association of intake of specific types of fatty acids with the prevalence of asthma symptoms using data from the Ryukyus Child Health Study.
Methods Study subjects were 25033 schoolchildren aged 6-15 years in Okinawa, Japan. Symptoms of wheeze and asthma were defined according to diagnostic criteria from the International Study of Asthma and Allergies in Childhood. Information on dietary factors was collected using a self-administered brief diet history questionnaire for children. Adjustment was made for age, sex, number of siblings, smoking in the household, body mass index, paternal and maternal history of allergic diseases, and paternal and maternal educational level.
Results Intake of polyunsaturated fatty acids, n-3 and n-6 polyunsaturated fatty acids and linoleic acid (18 : 2 n-6) was independently associated with an increased prevalence of wheeze - the multivariate odds ratios for the highest quintile were 1.19 (95% confidence interval [CI], 1.05-1.35), 1.17 (95% CI, 1.03-1.34), 1.19 (95% CI, 1.04-1.35), and 1.20 (95% CI, 1.06-1.37), respectively. There was no measurable relationship of consumption of alpha-linolenic (18 : 3 n-3), eicosapentaenoic (20 : 5 n-3), docosahexaenoic (22 : 6 n-3) or arachidonic acid (20 : 4 n-6) or the ratio of n-3 to n-6 polyunsaturated fatty acids with the prevalence of wheeze. Consumption of total fat, saturated fatty acids, monounsaturated fatty acids and cholesterol were not evidently related to wheeze. No material dose-response association was found between the intake of any of the types of fatty acids considered and the prevalence of asthma.
Conclusions The findings suggest that consumption of both n-3 and n-6 polyunsaturated fatty acids, especially linoleic acid, may be associated with an increased prevalence of wheeze.