Environmental exposures related to gut microbiota among children with asthma: a pioneer study in Taiwan

Gut microbiota plays a crucial role in human health and can be influenced by environmental factors. While past studies have examined the impact of the environment on gut microbiota, vulnerable populations have often been overlooked. This study aimed to investigate the association between environmental exposures, air pollution and greenspace, and gut microbiota in asthmatic children. Data were collected during the recovery period for 41 eligible children. Air pollution was estimated using an ensemble learning model that combined regression and machine-learning algorithms, while greenspace was quantified using the normalized difference vegetation index (NDVI) and green land-cover data. The lag effects of exposures were assessed within defined buffer zones surrounding each child's residence. A generalized additive model was applied to examine associations. Results revealed a marginally significant negative association between 1-day lag exposure to NO₂ and gut microbiota indices, such as observed bacteria (Coef.: -1.130; 95 %CI -2.287, 0.027) and bacterial richness (Coef.: -2.420; 95 %CI -4.987, 0.146). The 8-day lagged average exposure to PM_2.5 and O₃ also showed negative impacts on bacterial diversity. In contrast, the 1-month lagged average exposure to greenspace was positively associated with microbiota indices. Air pollution and greenspace were also linked to specific bacterial abundances, such as Streptococcus. This study underscores the need for further research on how environmental factors may influence immunity in asthmatic children by altering gut microbiota.