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.
CONCLUSIONS: 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.
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.
CONCLUSIONS: 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.
摘要：
背景：绿地暴露对人类微生物群的潜在影响已经通过许多观察和干预研究进行了探索，但结果喜忧参半。我们通过遵循系统评价和荟萃分析指南的首选报告项目进行系统评价，全面综合了这些研究。
方法：在三个国际数据库（PubMed，Embase,和WebofScience)和三个中文数据库(中国国家知识基础设施，万方,和中国生物医学光盘）从开始到2023年11月1日进行。包括评估不同解剖部位的绿地暴露与人类微生物群之间关联的观察性和介入性研究。使用国家毒理学计划办公室的健康评估和偏倚工具的翻译风险评估研究，并使用建议分级评估证据的确定性，评估,发展和评价框架。两名作者独立进行研究选择，数据提取,和偏见风险评估，和证据分级。对研究结果进行描述性综合。
结果：20项研究，包括11项观察性研究和9项干预性研究，最终被纳入系统综述。纳入研究的微生物群来自肠道(n=13)，皮肤（n=10），口腔（n=5），鼻腔（n=5）和眼睛（n=1）。大多数研究报告了绿地暴露与多样性增加的关联(例如，丰富度和香农指数)和/或人类肠道(n=12)和皮肤微生物群(n=8)的总体组成改变，随着益生菌相对丰度的增加(例如，反刍动物科)和病原体相对丰度的降低(例如，链球菌和大肠杆菌/志贺氏菌）。由于研究数量有限，关于绿地和口头的证据，鼻部,和眼部微生物群仍然没有定论。
结论：目前的证据表明，绿色空间暴露可能使肠道和皮肤微生物群多样化，并将其组成改变为更健康的特征。这些发现将有助于揭示绿色空间和人类健康的潜在机制，并促进更健康的人类微生物群。
方法：在三个国际数据库（PubMed，Embase,和WebofScience)和三个中文数据库(中国国家知识基础设施，万方,和中国生物医学光盘）从开始到2023年11月1日进行。包括评估不同解剖部位的绿地暴露与人类微生物群之间关联的观察性和介入性研究。使用国家毒理学计划办公室的健康评估和偏倚工具的翻译风险评估研究，并使用建议分级评估证据的确定性，评估,发展和评价框架。两名作者独立进行研究选择，数据提取,和偏见风险评估，和证据分级。对研究结果进行描述性综合。
结果：20项研究，包括11项观察性研究和9项干预性研究，最终被纳入系统综述。纳入研究的微生物群来自肠道(n=13)，皮肤（n=10），口腔（n=5），鼻腔（n=5）和眼睛（n=1）。大多数研究报告了绿地暴露与多样性增加的关联(例如，丰富度和香农指数)和/或人类肠道(n=12)和皮肤微生物群(n=8)的总体组成改变，随着益生菌相对丰度的增加(例如，反刍动物科)和病原体相对丰度的降低(例如，链球菌和大肠杆菌/志贺氏菌）。由于研究数量有限，关于绿地和口头的证据，鼻部,和眼部微生物群仍然没有定论。
结论：目前的证据表明，绿色空间暴露可能使肠道和皮肤微生物群多样化，并将其组成改变为更健康的特征。这些发现将有助于揭示绿色空间和人类健康的潜在机制，并促进更健康的人类微生物群。
