A huge community of organisms grows in our intestines, and they are the gut microbes that are closely related to our lives.
Gut microorganisms include what we often call gut flora, as well as viruses and eukaryotes. The intestinal flora is currently considered to have more than 2,000 species, with a number of 1014, more than the number of cells in the human body, mainly including the Firmicutes, Bacteroidetes, Actinobacteria, Proteobacteria. The Human Microbiome Project has shown that each individual’s intestinal flora is different and has its own specificity like fingerprints, and the microbiota of twins is nearly 50% similar, indicating that the genotype of the host plays a major role in the composition of the intestinal flora, and the human flora is relatively stable once established, while diet and drugs are the main factors that change its composition. Once established, the human flora is relatively stable, while diet and drugs are the main factors that change its composition. Studies have shown that eating a high-fat, high-sugar, high-protein diet for one day can significantly alter the intestinal flora. People on a high-fat diet have a predominance of Bacteroides intestinalis, while those on a high-carbohydrate diet have a predominance of S. intestinalis. The effect of antibiotics on intestinal flora is crucial, and some can even be devastating. Some colonies are difficult to recover for months after antibiotic application, and certain species can decrease or even disappear for a long time.
So, how is the human gut flora established? Previously, we thought that the fetus was sterile, but small amounts of bacteria have now been found to be present in the fetus. The delivery process is the body’s first exposure to bacteria, and the flora of a baby delivered naturally is similar to the mother’s vaginal flora, while the flora of a baby delivered by cesarean section is mainly skin flora such as Staphylococcus spp. and Propionibacterium spp. In early childhood, the intestinal flora is mainly aerobic bacteria, which are gradually replaced by anaerobic bacteria with the addition of complementary foods and solid foods.
What is the impact of intestinal flora on human body? Gut microorganisms have evolved with mammals for millions of years. The development and maturation of the mammalian immune system requires gut microorganisms, and animals in the sterile state show reduced sIgA, gastrointestinal tract-associated lymphoid tissue, Peyer’s vesicles, and mesenteric lymph node defects. The intestinal flora synthesize a variety of vitamins, such as B vitamins (vitamin B1, B2, B6, B12), vitamin K, niacin, pantothenic acid, etc. They also use protein residues to synthesize non-essential amino acids, such as aspartate, alanine, valine and threonine, and participate in the metabolism of sugars and proteins, and also promote the absorption of minerals such as iron, magnesium and zinc, and their decomposition of intestinal dietary fiber The short-chain fatty acids produced are an essential source of energy for colon cells.
The number of enteroviruses is about 108, and 95% of the viral population rarely changes during their lifetime. Contrary to our expectation, most enteroviruses are harmless to humans, but their specific composition and role still need to be further explored.
Many diseases have been found to be associated with alterations in the intestinal flora, such as allergic diseases, autoimmune diseases, obesity, diabetes, and Crohn’s disease. Crohn’s disease is a chronic and persistent inflammatory response caused by inappropriate response of the body’s immune tissues to intestinal microorganisms in response to environmental factors. Gut microbes play a crucial role in the pathogenesis of Crohn’s disease, and inflammation of the gut does not occur in animals in a germ-free state. Studies have shown that the intestinal flora of Crohn’s patients differs from the normal population, with a role for susceptibility genes as well as dietary and pharmacological factors, and it has been shown that Crohn’s patients can be treated for Crohn’s disease by taking capsules made from the feces of normal relatives through a gastric tube or swallowing them.
In conclusion, gut microbes are closely related to our health and disease, and our understanding of the relationship between gut microbes and disease is only just being unveiled at present, and more and more in-depth exploration is needed.