How gut bacteria heal and protect your brain

2024 Author: Seth Attwood | [email protected]. Last modified: 2023-12-16 15:55

Think of a situation where your stomach was twisting because you were nervous, anxious, afraid, or perhaps overjoyed. Maybe it happened on the eve of the wedding or when you had to take an important exam, speak in front of an audience. As scientists have found out, in fact, the close connection between the brain and the intestines is bilateral in nature: just as nervous experiences are reflected in the work of the intestines, the state of the intestines is reflected in the work of the nervous system.

The relationship between the gut and the brain

The vagus nerve, the longest of the 12 pairs of cranial nerves, is the main information channel between the hundreds of millions of nerve cells located in the digestive tract and the central nervous system. The vagus nerve is the tenth pair of cranial nerves. It leaves the brain and extends to the abdominal cavity, controlling many processes in the body that are not subject to the person's conscious control, including maintaining the heart rate and digestion.

Studies show that gut bacteria directly affect the stimulation and function of cells along the vagus nerve. Some of the gut bacteria are actually capable, like neurons, of producing information-carrying chemicals that speak to the brain in their own language through the vagus nerve.

When it comes to the nervous system, you are probably thinking about the brain and spinal cord. But this is only the central nervous system. In addition to it, there is also the enteric nervous system - a neural network located in the walls of the gastrointestinal tract. The central and enteric nervous systems are formed from the same tissue during embryonic development and are connected through the vagus nerve.

The vagus nerve got its self-explanatory name, probably because it diverges through the digestive system.

The number of nerve cells in the gastric mucosa is so great that many scientists today call their totality "the second brain". This "second brain" not only regulates muscle activity, controls immune cells and hormones, but also produces something very important. Popular antidepressants increase serotonin levels in the brain, making a person "feel good." You might be surprised to learn that approximately 80–90% of all serotonin is produced by nerve cells in the intestines!

In fact, the "second brain" produces more serotonin - the molecules of happiness - than the brain. Many neurologists and psychiatrists today conclude that this may be one of the reasons why antidepressants are often less effective in treating depression than dietary changes in patients.

In fact, recent research suggests that our "second brain" may not be "second" at all. He can act independently of the brain and without its help and influence independently control many functions.

You should understand that the cause of all diseases is an inflammatory process out of control. And the immune system exercises control over it. However, what does the intestinal microflora have to do with it?

It regulates the immune response, controls it, that is, it is directly related to the inflammatory process in the body.

Although each of us is constantly under threat from harmful chemicals and infectious agents, we have an amazing defense system - immunity. With a weakened immune system, a person instantly becomes a victim of numerous potential pathogens.

If the immune system is not functioning properly, even a simple mosquito bite can be fatal. But if you do not take such external events as a mosquito bite, every part of our body is inhabited by potentially life-threatening pathogens, which, if not for the immune system, could very well cause death. That being said, it is important to understand that the immune system functions optimally when it is in balance.

An overactive immune system can lead to complications such as allergic reactions, which in extreme manifestations are so intense that they can provoke fatal anaphylactic shock. In addition, if the functions of the immune system are impaired, it can stop recognizing the usual proteins of its own body and begin to attack them. This is the mechanism behind the onset of autoimmune diseases.

Traditional methods of their treatment are drugs that aggressively suppress the functions of the immune system, which often leads to serious negative consequences, including changes in the composition of the intestinal microflora. The action of the immune system is manifested in a situation when the patient's body rejects the transplanted organ, which should save his life. And it is the immune system that helps the body detect and destroy cancer cells - this process is going on inside your body right now.

The intestine has its own immune system, the so-called gut-associated lymphoid tissue (KALT, or GALT). It accounts for 70-80% of the body's immune system. This speaks volumes about the importance - and vulnerability - of our gut. If what happens in it did not have such an important effect on a person's vital activity, there would be no need for a significant part of the immune system to be located in the intestines, protecting the body.

The reason most of the immune system is located in the gut is simple: the gut wall is the border with the outside world. Apart from the skin, it is here that the body has the highest probability of interacting with substances and organisms foreign to it. In addition, it maintains constant communication with every cell of the immune system in the body. If a cell encounters a "suspicious" substance in the intestine, it puts the entire immune system on alert.

One of the important topics mentioned in the book is the need to preserve the integrity of this delicate intestinal wall, which is only one cell thick. It must be kept intact, while acting as a conductor of signals between the bacteria in the intestine and the cells of the immune system.

In 2014, at a conference exclusively dedicated to microflora, Dr. Alessino Fasano of Harvard University called these immune cells, which receive signals from gut bacteria, "the first responders." In turn, the bacteria in the gut help the immune system stay on guard, but not fully defensively. They monitor the situation and "educate" the immune system, which greatly helps to prevent its inappropriate response to food and provoking an autoimmune response.

Scientific research in both animals and humans has shown that “bad,” or pathogenic, bacteria can cause disease, but not just because they are associated with a particular condition.

For example, infection with the bacterium Helicobacter pylori is known to cause gastric and duodenal ulcers. However, this pathogenic bacterium also appears to interact with the gut immune system, triggering the production of inflammatory molecules and stress hormones, which causes the stress response system to switch to a mode of operation in which the body behaves as if it were being attacked by a lion. Recent scientific evidence also suggests that "bad" bacteria can alter the body's response to pain: in fact, people with unhealthy gut microflora may have a lower pain threshold.

Good gut bacteria do just the opposite. They try to minimize the number and consequences of their "bad" brethren, and also positively interact with both the immune and endocrine systems. Thus, the beneficial bacteria are able to "turn off" this chronic immune response. They also help keep cortisol and adrenaline levels under control, two stress-related hormones that can take a significant toll if they are constantly produced there.

Each major group of gut bacteria contains many different genera, and each of these genera can have a different effect on the body. The two most common groups of microorganisms in the gut, accounting for over 90% of the population of all gut bacteria, are Firmicutes and Bacteroidetes.

Firmicutes are known as “fat lovers” because bacteria in this group have been shown to have more enzymes to break down complex carbohydrates, which means they are much more efficient in extracting energy (calories) from food. In addition, relatively recently it was found that they play an important role in increasing the absorption of fats. Studies have shown that overweight people have higher levels of Firmicutes in their intestinal flora than lean people who are dominated by bacteria from the Bacteroidetes group.

In fact, the relative ratio of these two groups of bacteria, Firmicutes to Bacteroidetes (or F / B ratio), is a critical metric for determining health and disease risk. What's more, it has recently become known that higher levels of Firmicutes bacteria actually activate genes that increase the risk of obesity, diabetes and even cardiovascular disease. Think about it: changing the ratio of these bacteria can affect the expression of your DNA!

The two most well-studied bacterial genera today are Bifidobacterium and Lactobacillus. Don't worry about remembering these tricky names. In this book, you will come across complex Latin names for bacteria more than once, but I promise that by the end of the reading you will have no problem navigating bacteria of different genera. Although we cannot yet say with certainty what kind of bacteria and in what ratio determine the optimal state of health, according to the accepted opinion, the most important thing is their diversity.

It should be noted that the line between “good” and “bad” bacteria is not as clear-cut as you might think. I repeat that the important factors here are the general diversity and the ratio of different genera of bacteria relative to each other. If the ratio is incorrect, some genera of bacteria that can have a positive effect on the health of the body can turn into harmful ones. For example, the notorious bacterium Escherichia coli produces vitamin K but can cause serious illness. The bacterium Helicobacter pylori, which was already mentioned earlier due to the fact that it causes peptic ulcers, also has a useful function - it helps to regulate appetite so that a person does not overeat.

Another example is the bacterium Clostridium difficile. This bacterium is the main causative agent of a severe infectious disease if its population in the body becomes too high. The disease, whose main symptom is severe diarrhea, continues to kill nearly 14,000 Americans every year. The incidence of C. difficile infection has risen sharply over the past 12 years. In the period 1993-2005, the number of illnesses among the hospitalized adult population increased threefold, and in the period 2001-2005, it doubled. In addition, mortality has risen sharply, mainly due to the emergence of a mutated supervirulent species of this bacterium.

Usually we all have a significant number of C. difficile bacteria in our gut during childhood, and this does not cause problems. This bacterium is found in the intestines of about 63% of newborns and a third of babies at the age of four. However, a change in the intestinal microflora, provoked, for example, by the excessive use of certain antibiotics, can cause an excessive growth in the number of this bacterium, which can lead to the development of a deadly disease. The good news is that today we know of an effective way to treat this infection - using bacteria of other genera to restore the balance of the intestinal microflora. Published by econet.ru. If you have any questions on this topic, ask the specialists and readers of our project here.