Soy product and isoflavone intake associations with allergic diseases in Japanese workers: rhinitis, dermatitis and asthma.

Abstract

The aim of this study was to determine the associations of intake of soy products and isoflavones with allergic diseases. We conducted a cross-sectional study in 1437 participants (aged 20-64 years) who were living in Tokushima Prefecture, Japan during the period 2010- 2011. We obtained anthropometric data and information on life style characteristics including dietary intake and current medical histories of allergic diseases using a structural self-administered questionnaire. Multiple logistic regression models were used to assess the associations of soy products and isoflavones with allergic diseases after controlling for age, family history of allergic diseases, smoking, drinking, physical activity, energy intake, BMI and dietary factors. Intake of soy products showed significant inverse dose-response relationships with allergic rhinitis. The third quartile for soy products had an adjusted OR of 0.56 (95% CI: 0.35-0.91) compared to the reference group (first quartile), though intake of soy products showed no dose-response relationship with atopic dermatitis. Intake of soy isoflavones showed a significant inverse dose-response relationship with atopic dermatitis, though the association between intake of soy isoflavones and atopic dermatitis was U-shaped after adjustments for potential confounders. On the other hand, the associations between intake of soy isoflavones and other allergic diseases were not significant. The results indicate that higher intake of soy products is associated with reduced risk of allergic rhinitis in Japanese workers. Furthermore, moderate intake amounts of soy products and soy isoflavones are associated with inverse risk of atopic dermatitis.