Share:
A healthy intestinal flora also keeps the brain healthy
It has long been known that a healthy intestinal flora makes an important contribution to the protection against infections, allergies and other diseases. It may also protect the brain. According to a new study, the bacterial composition in the human intestine even has an effect on immune cells in the brain.
Healthy intestinal flora influences the course of Alzheimer's and MS
A new study suggests that a healthy gut flora apparently also protects the brain. Thus, colonization of the gut with bacteria for life affects the immune defense of the brain and thus possibly the course of brain diseases such as Alzheimer's disease and multiple sclerosis (MS). This is what a team of neuropathologists from Freiburg University Hospital in Breisgau has detected for the first time on mice. The scientists were able to prove that the function of brain cells, so-called microglia (also called brain macrophages), are controlled by breakdown products of intestinal bacteria. Especially in the decomposition of fiber bacteria produce short-chain fatty acids, which are needed for the correct function of the microglia.
A healthy intestinal flora counteracts infections and allergies, but it can also protect against diseases such as Alzheimer's or MS. (Image: rob3000 / fotolia.com) Balanced diet for the prevention of brain diseases
It turned out that mice whose intestines contained no bacteria develop immature and stunted microglia. Later, when a gut flora was established, the microglial cells became healthier again. Malformed microglial cells are reported to play a role in several brain diseases. How exactly the maturation and activation of these cells is controlled has not been clear so far. The researchers presented their results in the July issue of the renowned journal "Nature Neuroscience" and in advance in the online edition of the journal. The study not only gives indications of the possible development of neurodegenerative diseases, but also the importance of a balanced diet for the prevention of brain diseases.
Disturbed immune response after antibiotic therapy
Researchers found that animals reared and kept in a completely germ-free environment had stunted and immature microglia. The cells hardly responded to inflammatory stimuli in the brain. Even mice whose intestinal bacteria had been killed by a four-week antibiotic therapy had a disturbed immune response. However, when the mice came in contact with healthy conspecifics, a gut flora soon became established. The microglial cells were also healthier. "The greater the diversity of intestinal bacteria, the better the microglia also developed," says study director Marco Prinz.
High relevance also for humans
The study showed that short-chain fatty acids serve as a messenger between intestinal flora and microglia. These are produced when bacteria degrade fiber, dairy or other foods. "Our findings indicate how important a balanced diet is for mental health," Prinz said in a statement. But also bacteria that can produce short-chain fatty acids. In the intestinal rehabilitation sufferers therefore often get lactic acid-producing germs, such as lactobacilli and bifidobacteria in high doses. Another possibility is the ingestion of coli bacteria and other germ species. According to the researchers, the new study should also be highly relevant for humans. It was already known that misdirected microglial cells play a role in several brain diseases such as Alzheimer's dementia.
Treatment by chair transplant is being tested
As the scientists in the journal "Nature Neuroscience" report, associations with the intestinal flora could be found in inflammatory diseases of the brain such as multiple sclerosis. Accordingly, the results also suggest that autoimmune diseases of the intestine, such as Crohn's disease, are associated with a shortage of short-chain fatty acids. In this area, the treatment has been tested for some time by a so-called stool transplantation, in which the intestinal flora is transferred from one person to another. Even though such stool grafts have been used for a long time in cases of severe diarrhea and other intestinal problems, it can seem to lead to puzzling complications. Recently, a patient was reported to gain a lot of weight after stool transplantation. Doctors are still puzzling over the causes. (Ad)