What creatures still live in our bodies? This problem seems simple, but our understanding is not clear for a long time in history. In recent years, researchers have successively isolated human symbiotic microbes, which actually constitute most of the cells in our body. In human daily activities, symbiotic microorganisms are related to us.
The intestinal flora is so close to us that they protect us from infection, absorb food through digestion and gain nutrients for us, strengthen the intestinal mucosal barrier, and care for our throughout life. However, we have found that different intestinal flora affects people differently. We already know that obesity is closely related to the intestinal flora. The study found that a pair of twins, one fat and one thin, had the same genetic background, and transplanted the feces of two people to mice separately. The feeding conditions of the two groups of mice were identical, but the mice transplanted with fat feces became fat, and transplanted the mice of the lean stool did not. That is to say, if there are individuals and your genes are exactly the same, the diet is the same, but the difference in gut microbiota between them may lead to a very different situation. Studies have found that obese people or mice (or other mammals) have a common feature of the intestinal flora, which is that the composition of the flora is less, and the microbial biodiversity of obesity is lower. Of course, accidental use of antibiotics can also lead to Microbial diversity is reduced, but the most likely cause of reduced microbial diversity in obese people is diet. Excessive intake of fat and sugar, inadequate intake of dietary fiber, it is easy to get a lot of heat from food and reduce microbial diversity. Therefore, once obesity is identified and microbial diversity is reduced, we can investigate the causes of these microbial changes in the laboratory and trace back. What microbes are missing in the intestines of obese people?
The study found that Bifidobacterium is a probiotic that can be supplemented by drinking yogurt. It is also a bacteria that is lost in the intestine during the process of getting fat in humans and mice. Artificial intake increases the number of bifidobacteria and helps reduce obesity. Why do probiotics such as bifidobacteria achieve weight loss? Scientists have found that it is likely that these flora have an effect on inflammation. It has long been known that in obese people, the immune system appears to be at a lower level of inflammation, and the body continues to be stimulated by inflammation. This inflammation is most likely caused by lipopolysaccharide (LPS), a metabolite produced by specific microorganisms in the gut. Our immune system sees it as a “dangerous” signal and is ready to clear it. In the end, most beneficial bacteria will prevent LPS from reaching the intestine, while the obese people’s intestinal mucosal barrier is impaired, Bifidobacterium and other key bacteria are missing or reduced, LPS will directly enter the intestine and lead to inflammation, which may eventually lead to metabolic disease.
In addition to Bifidobacterium, which can prevent the invasion of LPS to a certain extent, recent studies have found that Akkermansia muciniphila also plays an important role. Akkermansia muciniphila was originally founded by Wageningen University (Netherlands). The team separated AKK in complex ecosystems, such as our intestines, which are closer to the intestinal wall than other bacteria. This bacteria provides nutrients to the intestinal mucosa, which is composed of mucus proteins secreted by our intestinal cells, which makes our intestinal mechanical movements smoother and maintains the intestinal flora at a relatively safe distance. A. muciniphila is also able to generate some molecular signals that stimulate and strengthen our intestinal wall. The maintenance of intestinal mucosal function by this bacterium is also beneficial to itself, because the intestinal mucosa is its main source of nutrition, and A. muciniphil resists LPS, maintains the integrity of the intestinal mucosa, and helps to improve the body’s immune system.
The study found that Akkermansia muciniphila has an important effect in the human body. For example, AKK has a higher level in long-lived humans, suggesting that it has a role in delaying aging; transplanting Akk bacteria in mice with amyotrophic lateral sclerosis (a neurodegenerative disease) significantly delays disease progression and prolongs survival in mice, suggesting that Akkermansia muciniphila has the effect of inhibiting the development of neurodegenerative diseases in the field of neurodegenerative diseases; supplementing AKK bacteria to overweight/obese human volunteers for three months orally, the insulin sensitivity of the volunteers was greatly improved, plasma total cholesterol was lowered, and liver dysfunction and inflammation-related markers were reduced. Interestingly, the study found that the AKK bacteria were better after heating and did not affect the stability of the intestinal flora.