In Vitro Simulation of Human Colonic Fermentation: A Practical Approach towards Models’ Design and Analytical Tools

The human colonic microbiota plays an important role in the food digestion process and has a key role in maintaining health status. This community of microbes is inter-individually different due to several factors that modulate its composition. Among them, diet is one of the most relevant, which, in turn, is affected by environmental, economic, and cultural considerations. These pieces of evidence have promoted the study of the influence of diet on gut microbiota and the development of in vitro models that simulate the colonic digestion of foods. This narrative review aims to present a technical approach of the in vitro gut models available to evaluate the impact of diet on human colonic microbiota. A description and comments on the main characteristics, parameters, applicability, faecal inoculum preparation, and analytical tools are made. Despite the progress of in vitro colonic digestion models and metaomic applicability in this research field, there are still some challenges to face due to the lack of a consensus on the methodologies to conduct in vitro colonic digestions and the need to integrate the metaomic data to fully understand the influence of food in human colonic microbiota.