The diversity of factors influencing human digestive microbiota in healthy adults and their interaction: A scoping review

Background / objectives Human digestive microbiota is affected by a wide variety of different factors. The objective of this study was to perform a scoping review that gathers and updates the information available about factors that affect human digestive microbiota in healthy adults. It is also reviewed if other factors are considered and if some type of interaction between them is studied. We searched in MEDLINE, Web of Science, Scielo, PROSPERO, and Cochrane databases. Two authors independently reviewed study eligibility and data extraction. Articles were classified based on the main factor studied upon one of the following categories: diet, habits, environment, or chemical exposure. Results The literature search provided a total of 73 studies that met the inclusion criteria. The presence of data about the influence of diet, habits, environment, and exposition to chemicals on digestive microbiota were registered. Analysis of the studies indicates that the assessment of risk factors is often focused on a specific aspect (diet, habits, environment, and chemicals) and the study of the interaction between factors is up to now not sufficiently investigated. In addition, there are some situations probably relevant to the human digestive microbiota that are not being assessed (snacking, intermittent fasting, type of sport practiced, living with pets or working with animals, type of transportation daily used, home cleaning habits, treatments with radiotherapy, immune suppressants, corticosteroids). Conclusions Little is known about the impact of the combined interaction of possible risk factors (diet, habits, environment, and chemical exposure) of dysbiosis in human digestive microbiota. Further studies are encouraged to evaluate more broadly the interactions between the risk factors that may influence the diversity of the human digestive microbiota. All of them are factors that act together every day on our health.