Influence of urban greenspace on the early-life gut microbiome

Abstract

Background. Emerging evidence suggests that early life exposure to trees and other vegetation (i.e., ‘greenspace’) may prevent development of allergies. A proposed biologic mechanism posits that human contact with natural environments affects the diversity of human commensal microbiota, thus promoting development of immunity. We conducted a pilot study to test the relationship of greenspace exposure in early life with gut microbiome diversity.Methods. We linked neighborhood environmental and sociodemographic measures from Drexel’s Urban Health Collaborative repository with data from a longitudinal birth cohort of children assembled from Children’s Hospital of Philadelphia, by census tract of the child’s residence at birth. Our pilot study included microbiome profiling of stool samples from 71 infants (born 2016-2018), from birth through 1-year of age. Overall greenness was derived from satellite imagery as the median normalized difference vegetation index (NDVI) in the summer months of 2016. We also assessed coverage of the census tract area by tree canopy and by grasses/shrubs, derived from the National Land Cover Database (2011) for the entire study region and from high-resolution landcover data for the City of Philadelphia (2008).Results. Greenspace of residential census tracts was associated with the change in gut microbial composition from age 1-12 months. In addition, cross-sectional associations were seen at age 1-month in Philadelphia. There was no association of greenspace with beta diversity at other ages (3, 6, or 12 months), nor with alpha diversity measures (species richness). The association of greenspace variables with the change in microbial composition from 1-12 months could not be linked to shifts in any particular microbial taxa.Conclusions. Our results suggest an influence of urban greenspace on development of the gut microbiome in early life. Given the potential to modify vegetation around homes in ways that may benefit health, robust investigation is warranted.