The microbiota i.e. all those good bacteria along our intestines, influencing the maturation of the immune system, affects our health and well-being and protect us from diseases such as allergies, diabetes and even cancer. That's why we often hear talk about the microbiota. It all starts with the birth, (eutocico) and during vaginal passage, begins the exchange of bacteria that will colonize the intestines of the unborn child and be able to educate the immune system to recognize what belongs all body (self), from what is foreign (non-self). It will speak, therefore, tolerance of immunological, this phenomenon will continue with the breast feeding and the exchange with the saliva of the mother. We can say that the microbiota of the mother, closely related to food choices, it is essential for proper immune development of their child, then why not pay attention all the nutrition during pregnancy'
It resides in the human gut ecosystem most densely populated of microorganisms that carry out essential functions in the homeostasis of the immune system in the metabolism of the host. The community of intestinal microorganisms (bacteria, fungi, protozoa and viruses) are collectively called "microbiota" and with all their genomes "microbiome" . The intestinal microbiota is continuously balanced with the gut-associated lymphoid tissue (gut-associated lymphoid tissue, GALT), the largest and most important immune organ of the human body .
Immunological homeostasis is the result of a continuous cross-talk between the microbiota and the mucosal immune system. The mucosal immune system is part of both the innate and adaptive, immune response. The host takes great advantages immunologically and metabolically by physical proximity between the gut microbial populations and underlying tissues, but at the same time this proximity is a continuing threat to health. In fact, the immune system must establish the right balance between "tolerance" to the intestinal microbiota, keeping sty- inflammatory tone, and "vigilance" with regard to infectious agents and opportunistic pathogens . The intestinal microbiota is also essential for the digestive activity and this action involves bacterial species that reside mainly in the colon. These microbiota promote breakdown, by fermentation, of Soluble fiber, disaccharides and peptides that escape digestion in the small intestine.
This fermentation produces, among other substances, short-chain fatty acid such as acetic acid, propionic acid and butyric acid. Short-chain fatty acids help to control fluid balance, as they are the primary energy source for colonocytes. Short-chain fatty acids improve the absorption of minerals and positively influence the metabolism of lipids and glucose in the liver.
The evolution of the microbial intestine begins at birth, ends during the first years of life and is highly customizable and stable in a healthy individual . At birth the intestinal tract is sterile, but soon develops a microbiota whose composition varies depending on factors such as the type of childbirth, nutrition during childhood, antibiotic use and diet, and then complete its maturation by the 3rd- 4th year of life . Acute or chronic disturbance of equilibrium of these intestinal microorganisms is therefore an important factor in many chronic diseases such as human inflammatory bowel disease, obesity, type 2 diabetes and cancer of the colon and rectum. This alteration called dysbiosis may be favored not only by an improper diet, use of antibiotics, stress and alterations of the sleep-veglia, but also chronic diseases that produce portal hypertension or alter the micro-level of the basal lamina of the gastro-intestinal tract contribute to this situation.
As a result of these perturbations, the number of bacteria such as lactobacilli and bifidobacteria decreases to the advantage of pathogenic species such as some clostridia and enterococci , but above all increases bacterial translocation generating an increased nonspecific immunological response.
The intestinal microbiota (1013-1014 cells/intestinal contents) is the most complex ecosystem found in nature that is home to several hundred species of bacteria. These bacteria belong to the phylum Bacteroidetes, Firmicutes, Proteobacteria, and Actinobacteria Fusobacteria. This microbiota is commonly referred to as our hidden metabolic 'organ' due to their immense impact on human wellbeing, including host metabolism, physiology, nutrition and immune function. These communities, characterized by metabolic specialization, complementarity and cooperation, are a very complex network of interaction microbe-microbe and microbe-host (intestinal brain).