Association between residential greenness and gut microbiota in Chinese adults.

Background: A growing body of studies have reported the health benefits of greenness. However, less is known about the potential beneficial effects of residential greenness on gut microbiota, which is essential to human health. In this study, we aim to examine the association between residential greenness and gut microbiota in a population-based cohort study.

Methods: We included 1758 participants based on the China Multi-Ethnic Cohort (CMEC) study and collected their stool samples for 16S sequencing to derive gut microbiota data. Residential greenness was estimated using the satellite-based data on enhanced vegetation index (EVI) and the normalized differential vegetation index (NDVI) in circular buffers of 250 m, 500 m, and 1000 m. The relationships between residential greenness levels and the composition of gut microbiota, measured by standardized α-diversity and taxonomic composition, were assessed using linear regression and Spearman correlation weighted by generalized propensity scores.

Results: Higher greenness levels were significantly positively associated with standardized α-diversity. Per interquartile range (IQR) increase of EVI and NDVI in the circular buffer of 250 m were associated with the increments of 0.995(95% confidence interval (CI): 0.212-1.778) and 0.653(95% CI: 0.160-1.146) in the standardized Shannon index. For the taxonomic composition of gut microbiota, higher greenness levels were significantly correlated with 29 types of microbial taxonomic composition. NDVI in the circular buffer of 250 m was associated with increased Firmicutes (r = 0.102, adjusted p value = 0.004), which was the dominant composition in the gut microbiota.

Conclusions: Increased amounts of residential greenness may support healthy gut microbiota by benignly altering their composition. These findings suggested that green spaces should be designed to support diverse gut microbiota and ultimately optimize health benefits.