Respiratory symptoms among schoolchildren of Taiwan: Environmental, dietary and lifestyle risk factors

The goal of this study was to assess the prevalence of asthma and respiratory symptoms among children in metropolitan Taipei, Taiwan, and the associated effects of residential, dietary, and lifestyle factors. Fifth grade schoolchildren in two school districts with the highest and lowest yearly concentration of particulate matter (< 10 mum diameter) in ambient air were used in the study. A structured child questionnaire was used to elicit the pupils' experiences of asthma and respiratory symptoms and to gather information on the characteristics of their residential environment, dietary pattern, and lifestyle. A parental questionnaire was used to confirm the children's responses.;Among the 2218 schoolchildren, 9.8% reported having physician-diagnosed asthma. The prevalence of respiratory symptoms ranged from 9.8% for wheezing with cold to 40.5% for exercise-induced cough. The residential factors, including chemical vapors, gas leaks, dampness, cockroaches, and pets increased the risk of respiratory symptoms and asthma (all P<0.05). Frequent consumption of sweetened beverages, eggs, and meat were positively associated with the occurrence of respiratory symptoms and suspected asthma, whereas frequent consumption of soy products, fruits, seafood, and dairy were negatively associated with respiratory symptoms (all P<0.05). Overweight and extended TV-watching time were associated with increased risk of respiratory symptoms, while frequent physical exercise was associated with lower risk of respiratory symptoms (all P<0.05). Schoolchildren with doctor-diagnosed asthma had higher percentages of absenteeism and poor quality of life (all P<0.05). Parents reported fewer experiences of respiratory symptoms among their children compared to the children's reports. In general, the children's reports showed more sensitivity to the respiratory symptoms, but the parents' reports were better reflector of measures of symptoms specificity.;The results suggest that in addition to residential factors, dietary and lifestyle factor significantly play a role in respiratory health of children. Consumption of food, such as sweetened beverages and eggs, increase the risk of respiratory illness, which may be due to food allergens or the stimulating effect of cold beverage. In contrast, the beneficial effects of soy products and fruit may be due to isoflavone or antioxidant components. Overweight increases the risk of respiratory symptoms partly due to physiological changes, whereas appropriate physical exercise raises the threshold for diseases. The study further suggests that weight status, sedentary life, and frequency of physical exercise together have a strong moderating influence on the respiratory health of children.