Can intestinal bacteria regulate our blood cholesterol levels?

we all know that elevated serum cholesterol levels are one of the risk factors for atherosclerosis. However, cholesterol is also an important part of the epidural membrane, is also a prelude to the synthesis of bile acid and steroid hormones, the body's daily health and physiological function is essential, so cholesterol levels are too low is also unhealthy. Therefore, cholesterol metabolism needs to be strictly regulated.cholesterol metabolism is precisely regulated by a variety of factors, so that serum cholesterol levels remain stable. Serum cholesterol levels are mainly affected by absorption, synthesis and discharge. Increased or reduced cholesterol absorption and synthesis can lead to the destruction of cholesterol stability and lead to increased serum cholesterol levels.more and more studies have shown that the number and type of intestinal bacteri groups play an important role in maintaining the normal physiological state of living organisms, and that disorders of intestinal virlobes can lead to disease. Mice struck by the ApoE gene are widely used animal models of atherosclerosis, and the absence of intestinal bacterios (aseptic conditions) accelerates their atherosclerosis when fed a standard low-cholesterol diet. Intestinal bacteria can also regulate lipid metabolism in mice. Conventionally reared mice with normal intestinal bacteria had lower cholesterol levels than sterile mice. These facts show that there is a link between the gut bacteria and blood cholesterol levels.The intestinal bacteribus regulates the host's cholesterol steady statethe source of cholesterol in the body there are two main ways, one is an exogenous pathway, that is, from food intake, the other is an endogenous pathway, that is, the body's own synthesis. The body mainly through its own synthesis of cholesterol to meet physiological needs, almost all cells can synthesize cholesterol, but the liver is the main organ of cholesterol synthesis.cholesterol transport is also a key to maintaining cholesterol stability, the body's cholesterol is mainly in the form of lipoprotein transport, we are familiar with high-density lipoprotein (HDL) and low-density lipoprotein (LDL). HDL mainly transports cholesterol from the outer tissue back to the liver so that it is reused or broken down to prevent excessive accumulation of cholesterol in cells and blood, which is also used as a reverse transport of cholesterol. LDL mainly transports cholesterol to exocytes.the liver can use cholesterol to make bile acid, the main component of bile. Bile acid is secreted into the tighurl, which helps the lipids digest and absorb, and then at the end of the empty intestine or back into the intestine, which in turn flows back into the liver through the door vein system, which is the intestinal liver circulation of bile acid. Most bile acid is re-absorbed by the body and returned to the liver, with the rest excreted through feces (about 5%). If cholesterol is re-absorbed from the intestines, the liver extracts more cholesterol from the blood to compensate for raising cholesterol to make bile acid, which lowers blood cholesterol levels., like cholesterol and bile acid, there is a circulation of the liver. The liver secretes a certain amount of cholesterol into the bile, and then with the bile secreted into the small intestine, the small intestine also ingests cholesterol in the intestinal cavity, including food sources of cholesterol and bile cholesterol, through the veins back to the liver, which is cholesterol in the liver circulation., cholesterol absorption, synthesis, transport, and bowel circulation of bile acid and cholesterol together affect blood cholesterol levels. To investigate whether intestinal bacteria affect these processes, the researchers used broad-spectrum antibiotics to remove the ApoE gene from the intestinal bacteria in mice and then looked at the effects on cholesterol stability. So, what did you find?using antibiotics to remove the gut bacteria in mice raises plasma cholesterol levels. Cholesterol in plasma is mainly present in the form of lipoproteins, including celiac particles, very low-density lipoprotein (VLDL), low-density lipoprotein (LDL) and high-density lipoprotein (HDL). There was a significant increase in VLDL and LDL levels in mice where antibiotics cleared the gut bacteria, which are often considered "bad cholesterol".removal of intestinal bacteria increases the absorption of intestinal cholesterol, and gene expression involving intestinal cholesterol absorption in the empty intestine increased significantly in mice with intestinal bacterial bacteria removed.intestinal bacteria can increase the liver's intake of cholesterol through LDL absorber.removal of intestinal bacteria increases the synthesis of cholesterol in the liver. HMGCS1 and HMGCoAR are two key enzymes in the cholesterol biosynthesis pathway, and the expression of these two enzymes in the liver increased significantly by 4-7 times after the removal of the intestinal bacteria.removal of the gut bacterium group will also increase the synthesis of bile acid in the liver, the liver bile acid synthesis pathway speed limit enzyme expression significantly increased, in addition, cholesterol through the bile discharge also significantly increased., the presence of gut bacteria is critical to the stability of cholesterol throughout the body, strongly regulating blood cholesterol levels, liver cholesterol synthesis, and intestinal liver circulation. The removal of intestinal bacteria can lead to an imbalance in the circulation of cholesterol into the liver, leading to the accumulation of cholesterol, especially in the blood.Blood cholesterol levels can be transmitted through bacterial transplantation the presence or not of the intestinal bacteria can seriously damage the host's cholesterol metabolism, then changes in the composition and function of the intestinal bacteria will also induce changes in blood cholesterol levels?There was a significant difference between the gut bacteria of patients with hypercholesterolemia (elevated serum total cholesterol, triglycerides and LDL levels) and those with normal blood cholesterol, and the richness and diversity of the intestinal bacteria in patients with hypercholesterolemia were lower than those with normal blood cholesterol.If the intestinal virlocy of subjects with elevated total blood cholesterol levels and normal cholesterol levels were transferred to mice that had been cleared of the intestinal bacteria by antibiotics, the total blood cholesterol levels of those subjects who received hypercholesterolemia were significantly higher, and other lipid levels, such as triglycerides and phospholipids, were significantly higher. Therefore, not only the presence or failure of the intestinal bacteria, the composition of the intestinal bacteria is also sufficient to affect blood cholesterol levels.mice that received high cholesterolemia also had increased intestinal cholesterol absorption, while liver cholesterol intake and synthesis decreased, and the secretion of bile cholesterol in the intestinal cavity decreased. This further confirms that the gut bacteria are involved in regulating the balance between cholesterol absorption and liver synthesis.particular class of gut bacteria involved in cholesterol metabolism, affecting the host's cholesterol levels the human gut bacterium has a wide range of metabolic capacity. Researchers from the Massachusetts Institute of Technology and Harvard University have found that a particular class of gut bacteria may be able to metabolize enough cholesterol to affect blood cholesterol levels.People who carry these particular gut bacteria have lower levels of cholesterol in their blood than those who don't, which may explain why some people eat more cholesterol in their diet with little effect on their blood cholesterol levels.this particular gut bacteria produce an enzyme called cholesterol dehydrogenase IsmA, which is involved in the metabolic activity of cholesterol in the gut into manuresterol. If a person's gut bacterium carries a synthetic gene for this dehydrogenase, his feces and serum cholesterol levels will be significantly lower, and the effects may even be comparable to changes in the lipid-stabilized gene., cholesterol metabolism in the gut bacteria may play an important role in reducing intestinal and blood cholesterol levels, directly affecting human health.small knots the intestinal bacteria involved in regulating the absorption, synthesis and transport of cholesterol, is essential to maintain the stability of cholesterol throughout the body. The absence of intestinal bacteria can lead to an imbalance in the circulation of cholesterol, which can lead to the accumulation of cholesterol, especially in the blood.not only does the absence of intestinal bacteria seriously damage the host's cholesterol metabolism, but changes in the composition of the gut bacteria are enough to affect blood cholesterol levels. Blood cholesterol levels were passed through intestinal bacteria transplantation, and blood cholesterol levels were significantly higher in mice that transferred high-cholesterol human subjects' gut bacteria to antibiotics to remove the gut bacteria. This also proves to some extent the causal effect of intestinal bacteriocycus in regulating blood cholesterol levels.A particular class of bacteria in the human gut bacterium can produce cholesterol dehydrogenase, metabolize cholesterol into manuresterol, thereby lowering cholesterol levels in the gut and blood, which may also be the reason why some people eat more cholesterol in their diet but maintain lower serum cholesterol levels., a healthy and balanced gut bacteria regulates the balance of cholesterol absorption and synthesis, maintaining a steady state of host cholesterol. Differences in the gut bacteria between individuals affect the metabolism of cholesterol, which in effect affects serum cholesterol levels. Maintaining healthy cholesterol levels simply by limiting the amount of cholesterol in food is meaningless, and efforts should be made to create a healthy and balanced gut microbiome environment. Balancing cholesterol levels by regulating the gut bacterios, it also opens up new possibilities for the prevention and treatment of cardiovascular disease.:
1.Rebolledok, C., et al. (2017). " Bacterial Community Profile of the Gut Microbiota Differs between Hypercholesterolemic Subjects and Controls." BioMed Research International 2017: 8127814.
2.Le Roy, T., et al. (2019). "The intestinal microbiota regulates host cholesterol homeostasis." BMC Biol 17(1): 94.
3.Kenny, D. J., et al. (2020). "Cholesterol Metabolism by Uncultured Human Gut Bacteria Influences Host Cholesterol Level." Cell Host Microbe 28(2): 245-257 e246.