Modification of effect between air pollution and lung function by the inflammatory potential of diet: a cross sectional study in children

Fine particulate matter (PM) can cause systematic inflammation and oxidative stress, which can worsen asthma development and progression. Intake of fatty acids and antioxidants may attenuate some effects of PM but the role of overall dietary intake has not been studied. We aimed to investigate the modification of the association between air pollution and childhood asthma by the dietary inflammatory potential effect. In a cross-sectional study, 501 (48.1% males, aged 7 to 12 years) of 858 children attending 71 classrooms from 20 schools were selected. Spirometry and airway reversibility, exhaled nitric oxide, skin-prick testing and current symptoms (breathing difficulties and irritative cough) were assessed. Dietary inflammatory potential was evaluated by the Dietary Inflammatory Index (DII) and calculated from a 24-hour dietary recall. Indoor air quality measurements were conducted in classrooms for one week. The proportion of effects explained by the exposures to PM2.5 and PM10 were measured by generalized linear mixed model. After adjustments, an inflammatory diet increased the risk of asthma for PM2.5 (OR=1.67, 95% CI 1.03, 2.73) and PM10 (OR= 1.75, 95% CI 1.07, 2.87) levels. Considering the dietary inflammatory potential in PM2.5 and PM10 exposure, the risk of asthma increased in parallel with the DII, being significant for children with asthma (OR= 0.89, 95% CI 0.81, 0.97 and OR= 0.92, 95% CI 0.87, 0.97). These findings provide further support to the role of diet’s inflammatory characteristics modulating the effects of indoor air pollution, highlighting the importance of children’s diet as a potential solution to reduce the asthma risk.