Increasing childhood asthma rates may be due to changing dietary lifestyle. We investigated the association of dietary intake of antioxidant vitamins and fatty acids with asthma in Japanese pre-school children.

Cross-sectional study.

School-based survey on lifestyle/diet and health status in children in Japan.

Parents of 452 children aged 3–6 years completed a questionnaire on the children's and parents’ lifestyle and demographics. Children were classified into asthma cases and non-asthma cases in accordance with the ATS-DLD (American Thoracic Society and Division of Lung Diseases of the National Heart, Lung, and Blood Institute) questionnaire. Children's diet was assessed using a 3 d dietary record completed by parents. Children's age, sex, BMI, history of food allergy, maternal age, parental history of allergy, maternal education, family size and second-hand smoking were included as covariates. Logistic regression models were used to examine the association between children's diet and asthma.

Compared with children with the lowest intake tertile for vitamin C and vitamin E, those in the highest were significantly inversely associated with asthma; adjusted OR (95 % CI) were 0·35 (0·14, 0·88) and 0·32 (0·12, 0·85), respectively. A statistically significant trend was also observed. Fruit intake showed an inverse but insignificant association with asthma. There were no associations of any type of fatty acids with asthma.

These data suggest that children with high intakes of vitamins C and E may be associated with a reduced prevalence of asthma.