During the IBSDAYS congress, held in Bologna (Italy) last june, Microbiomepost sat down with Francisco Guarner, from Centro Médico Teknon in Barcelona (Spain) to discuss the most recent researches in the field of microbiome and nutrition.

Over the past two decades, research on the gut microbiota has clarified the central role played by colonic bacteria in the digestion of plant-based foods and in the regulation of the immune system. Many intestinal microorganisms break down fibers and other plant components, making nutrients and bioactive compounds available to the host, including several phytochemicals with antioxidant properties. These bacteria are highly dependent on the host and establish a mutualistic relationship in which the human body provides space and nutrients, while the microorganisms contribute essential metabolic functions.

The gut microbiota also supports immune system development through continuous interaction with the lymphoid tissue distributed along the gastrointestinal tract. Some bacteria promote the development of regulatory T cells, which are essential for controlling immune responses, while others, such as segmented filamentous bacteria, stimulate inflammatory responses that help protect against pathogens. Proper immune function therefore depends on a balance between regulatory signals and immune activation.

In industrialized societies, the loss of certain bacteria with regulatory functions may contribute to the increasing prevalence of allergies and autoimmune diseases. A diet rich in plant-based foods could help restore these microbial functions, although individual intolerance to fiber and vegetables remains an important limitation. Future research should therefore focus on personalized dietary strategies capable of promoting the growth of beneficial bacteria without triggering gastrointestinal symptoms.