Environmental factors and diet may explain the higher rates of asthma seen in developed countries

Environmental factors and diet may explain the higher rates of asthma seen in developed countries, suggest researchers in this week's BMJ.

The study involved 10,902 primary school children from three cities in China at different stages of modernisation (Hong Kong, Beijing and Guangzhou). Parents were asked about asthmatic symptoms and exposure to environmental factors.

A smaller group of children from each city underwent a skin prick test for sensitivity to eight common allergens, such as pollen and dust. Consumption of fruit and raw vegetables was also recorded.

Asthmatic symptoms were up to three times more common in children from the more developed Hong Kong than in those from mainland China.

Factors significantly associated with wheeze were cooking with gas, foam pillows, and damp housing. Factors protecting against wheeze were cotton quilts and frequent consumption of fruit and raw vegetables.

Environmental factors and diet may explain the differences in prevalence of asthma between children living in different regions of China, conclude the authors.