Manipulation of the Intestinal Microbiota: the Medicine Revolution of the 21st Century.

Arq Gastroenterol • 2017. v. 54 no 2 Abr/Jun • 83 Bacteria usually co-exists with humans for millennium, and can be found in our bodies in many places, most of them in the gastrointestinal tract. They constitute the human microbiome formed by a great variety and diversity of microorganisms. It is estimated that 70% of these microorganisms are concentrated in the intestine, particularly in the colon, forming the intestinal microbiota, with up to 1011 bacteria per milliliter. It shelties about 3 million microbial genes, corresponding to 150 times the human genome. The set formed by microbial cells and genes added to human cells and genes creates the concept of “superorganism”. Before birth, there are no bacteria present in the digestive tract, but in childbirth, their colonization happens quickly. The intestinal microbiota begins to settle from 2 to 3 years of age and, from there, remains relatively stable. However, this stability can be influenced by diet, diseases, use of medications (mainly antibiotics) and aging. This microbiota is composed of commensal bacteria (native to the host) or temporary bacteria (passing through the body). Both can be beneficial, potentially harmful or pathogenic to humans. The beneficial bacteria interact positively with the human immune system, provoking a competitive inhibition with the pathogens bacteria, keeping the intestinal microbiota in a balance called eubiosis. The genre of bacteria with the greatest health benefit are Bifidobacterium and Lactobacillus. Recent researches suggests that the normal intestinal microbiota is not simply a collection of microorganisms but reflects an interrelationship between different genre of bacteria that possibly work together to benefit the host. It is now believed that the existence of a large diversity of microorganisms in the gastrointestinal tract is important and beneficial for the host. A healthy microbiota plays an important role in digestion and absorption of nutrients, production of vitamins, maintenance of the structural and functional integrity of the intestine, protection against pathogens and modulation of the inflammatory response through the interaction of the microbiota and the immune system (gut associated lymphoid tissue – GALT). Manipulation of the intestinal microbiota: the medicine revolution of the 21st century