[Gut microbiota and its modulation: impact on digestive health and immune system]

The development of new omics sciences has made it possible to investigate the correlation of alterations in different microbiota of our organism (dysbiosis) with the appearance of many diseases and, of course, with the maintenance of health, although the causality is not well known currently. However, this fact has led to its modulation, mainly through diet and the use of probiotics and prebiotics, becoming a new therapeutic target by improving the structure and functions of the gut microbiota by optimizing bacterial diversity. Gut microbiota has been demonstrated to contribute to host's nutrition through its digestive and metabolic activity and to its body development through trophic effects on the intestinal mucosa, the local and systemic immune system and distant organs (liver, heart, lungs, central nervous system). The diversity of species in this ecosystem increases its genetic resources and facilitates the survival of all its components. Therefore, the implication of the gut microbiota on the pathogenesis of different gastrointestinal diseases, such as functional digestive disorders, has been investigated. In addition, microbial interactions are essential in the maturation of the immune system and there is a relationship between the microbial community and the mucosal immune system whose underlying mechanisms are of great importance in the first years of life. This interaction, together with genetic and environmental factors, results in a composition and richness of the microbiota that can have a major influence on the health/disease binomial.