Child's microbiome and malnutrition

In the gut, the initial microbial population is quite heterogeneous. Regulatory mechanisms generated within habitats (such as immunity and physicochemical environments conditions) and external forces (types of nutrients, environmental contamination and use of antimicrobials) allow the continued presence of some types of microorganisms and the elimination of others. Subsequently, the composition of the microbiota becomes more stable, and the normal adult bacterial community is reached. The children will reach a microbiota with characteristics of adult or community climax around the 2 years of age. From this period, although the intestinal microbiota remains in permanent interaction with microorganisms of the environment, its composition remains stable. The maintenance of eubiosis in the gut depends on diet, providing substrate to microbiota members, as well on the integrity of the epithelial cells and immune tissues. These structures together form the intestinal barrier. Damage in one of the structures of the barrier will lead to a dysbiosis status. Situations of undernutrition and overweight have a direct impact and relation with dysbiosis. In undernutrition situations there is a permanent immaturity of the microbiome together with a disruption of the barrier. Therefore, there is a delay in nutrient absorption as well an impaired immune system. In an overweight situation, there is also a disruption of intestinal barrier, relating to diet and a detriment microbial composition. There is an increase of energy intake and systemic effects on the host such as increased adiposity and inflammation. The breast milk can configurate gut microbiome, facilitating optimal microbial colonization. Human milk oligosaccharides stimulate some bacterial genera, such Bifidobacterium longum subsp infantis, which will provide a stable and eubiotic status in infant gut microbiome. Breast milk also improves immune condition and nutritional source. Understanding how the microbial-host interactions occurs, and the effects of diet and breast milk on eubiotic status, we can propose some possibilities to deal with double burden of malnutrition. (author)