Greenspace and human microbiota: A systematic review

Yi-Dan Zhang; Gang-Long Zhou; Lu Wang; Matthew H E M Browning; Iana Markevych; Joachim Heinrich; Luke D Knibbs; Tianyu Zhao; Yizhen Ding; Shi Chen; Kang-Kang Liu; Payam Dadvand; Guang-Hui Dong; Bo-Yi Yang

doi:10.1016/j.envint.2024.108662

Greenspace and human microbiota: A systematic review

Environ Int. 2024 Apr 16:187:108662. doi: 10.1016/j.envint.2024.108662. Online ahead of print.

Authors

Yi-Dan Zhang¹, Gang-Long Zhou¹, Lu Wang¹, Matthew H E M Browning², Iana Markevych³, Joachim Heinrich⁴, Luke D Knibbs⁵, Tianyu Zhao⁶, Yizhen Ding⁷, Shi Chen⁸, Kang-Kang Liu⁹, Payam Dadvand¹⁰, Guang-Hui Dong¹, Bo-Yi Yang¹¹

Affiliations

¹ Joint International Research Laboratory of Environment and Health, Ministry of Education, Guangdong Provincial Engineering Technology Research Center of Environmental Pollution and Health Risk Assessment, Department of Occupational and Environmental Health, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China.
² Department of Park, Recreation, and Tourism Management, Clemson University, Clemson, SC 29634, USA.
³ Institute of Psychology, Jagiellonian University, Krakow, Poland.
⁴ Institute and Clinic for Occupational, Social and Environmental Medicine, LMU University Hospital Munich, Munich 80036, Germany; Allergy and Lung Health Unit, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, VIC 3010, Australia.
⁵ School of Public Health, The University of Sydney, Camperdown, NSW 2006, Australia; Public Health Research Analytics and Methods for Evidence, Public Health Unit, Sydney Local Health District, Camperdown, NSW 2025, Australia.
⁶ Institute and Clinic for Occupational, Social and Environmental Medicine, LMU University Hospital Munich, Comprehensive Pneumology Center (CPC) Munich, German Center for Lung Research (DZL), Munich 80036, Germany; Institute of Epidemiology, Helmholtz Zentrum München - German Research Center for Environmental Health, 85764 Neuherberg, Germany.
⁷ Department of Landscape Architecture and Urban Planning, Texas A&M University, College Station, TX 77843, USA.
⁸ School of Public Health, Sun Yat-Sen University, Guangzhou 510080, China.
⁹ Department of Research Center for Medicine, the Eighth Affiliated Hospital, Sun Yat-Sen University, Shenzhen, China.
¹⁰ ISGlobal, Dr. Aiguader 88, 08003 Barcelona, Spain; CIBER Epidemiología y Salud Pública (CIBERESP), Madrid, Spain.
¹¹ Joint International Research Laboratory of Environment and Health, Ministry of Education, Guangdong Provincial Engineering Technology Research Center of Environmental Pollution and Health Risk Assessment, Department of Occupational and Environmental Health, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China. Electronic address: yangby23@mail.sysu.edu.cn.

PMID: 38653130
DOI: 10.1016/j.envint.2024.108662

Abstract

Background: Potential effect of greenspace exposure on human microbiota have been explored by a number of observational and interventional studies, but the results remained mixed. We comprehensively synthesized these studies by performing a systematic review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

Methods: Comprehensive literature searches in three international databases (PubMed, Embase, and Web of Science) and three Chinese databases (China National Knowledge Infrastructure, Wanfang, and China Biology Medicine disc) were conducted from inception to November 1, 2023. Observational and interventional studies that evaluated associations between greenspace exposure and human microbiota at different anatomical sites were included. Studies were assessed using the National Toxicology Program's office of Health Assessment and Translation risk of bias tool and certainty of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluation framework. Two authors independently performed study selection, data extraction, and risk of bias assessment, and evidence grading. Study results were synthesized descriptively.

Results: Twenty studies, including 11 observational studies and 9 interventional studies, were finally included into the systematic review. The microbiota of the included studies was from gut (n = 13), skin (n = 10), oral cavity (n = 5), nasal cavity (n = 5) and eyes (n = 1). The majority of studies reported the associations of greenspace exposure with increased diversity (e.g., richness and Shannon index) and/or altered overall composition of human gut (n = 12) and skin microbiota (n = 8), with increases in the relative abundance of probiotics (e.g., Ruminococcaceae) and decreases in the relative abundance of pathogens (e.g., Streptococcus and Escherichia/Shigella). Due to limited number of studies, evidence concerning greenspace and oral, nasal, and ocular microbiota were still inconclusive.

Conclusion: The current evidence suggests that greenspace exposure may diversify gut and skin microbiota and alter their composition to healthier profiles. These findings would be helpful in uncovering the potential mechanisms underlying greenspace and human health and in promoting a healthier profile of human microbiota.

Keywords: Gut; Human microbiota; Nature environment; Systematic review; Vegetation.