Asthma,eczema, and reports on pollen and cat allergy among pupils in Shanxi province,China

Objectives To study self-reported asthma, eczema, and pollen and furry pet allergy among pupils (9–20 years) in Shanxi province, China, in relation to dietary and environmental factors. Methods A standardised questionnaire was distributed to pupils in two primary and two secondary schools, one in Taiyuan city (3.0 milj. inhabitants), the others in Qingxu county, a rural area 30 km outside Taiyuan. Totally, 2,116 pupils (90%) participated. Results Fifty percent were girls, 61% had been growing up on the countryside, 18% lived in Taiyuan now, 1.7% had ever had asthma, 0.8% had doctor’s diagnosed asthma, 1.4% pollen allergy, 1.7% cat allergy, and 0% had dog allergy. Multiple logistic regression was applied, controlling for age, gender, diet, indoor exposures, rural childhood, and current urban residency. Girls had less eczema (OR = 0.51; 95%CI 0.28–0.92). Pupils in the city had more eczema (OR = 5.05; 95% CI 1.11–23.3). Those with a rural childhood had less asthma (OR = 0.17; 95% CI 0.05–0.60), eczema (OR = 0.15; 95% CI 0.13–0.66) and pollen/cat allergy (OR = 0.50; 95%CI 0.25–0.99). None of the indoor variables was related to asthma or allergy. Children with frequent fruit consumption had less asthma (OR = 0.40; 95% CI 0.19–0.82) and pollen/cat allergy (OR = 0.49; 95% CI 0.29–0.84). Those with frequent fish consumption had less asthma (OR = 0.32; 95% CI 0.11–0.97). Those with frequent hamburgers consumption had more asthma (OR = 2.05; 95% CI 1.09–3.87) and eczema (OR = 1.85; 95% CI 1.12–3.04). Conclusion Asthma, eczema, and pollen or pet allergy was uncommon, compared with western countries and other areas in China. Pupils with a rural childhood had less asthma and allergy, which is consistent with the “hygiene hypothesis”. Fruit and fish consumption may reduce, and fast food consumption may increase the risk for asthma. Finally, the higher prevalence of asthma and eczema among younger children, born in the 1990s, indicates a cohort effect similar to that observed in western countries.