How intestinal bacteria heal and protect your brain

US, WASHINGTON (ORDO NEWS) — Remember the situation when your stomach was twisting due to the fact that you were nervous, worried, felt fear or, perhaps, were overjoyed. Maybe this happened on the eve of the wedding, or when you had to pass an important exam, to speak in front of an audience.

As scientists have found out, in fact, the close relationship between the brain and intestines is bilateral: just like nervous experiences affect the work of the intestine, the state of the intestine affects the work of the nervous system.

The relationship of the intestines and the brain

The vagus nerve (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 conscious control of a person, including responsible for maintaining the heart rate and the digestion process.

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

When it comes to the nervous system, you probably imagine 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 interconnected through the vagus nerve.

The vagus nerve got its talking name, probably because it diverges along the digestive system. The number of nerve cells in the mucous membrane of the stomach is so great that many scientists today call their combination 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 the level of serotonin in the brain, so that a person “feels good.” You might be surprised to learn that approximately 80–90% of the total volume of serotonin is produced by nerve cells in the intestines! In fact, the “second brain” produces more serotonin – 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 changes in patients ’diet. In fact, the results of recent studies indicate that our “second brain” may not be the “second one” at all. It 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 that has gone out of control. And the immune system controls it.

However, what does the intestinal microflora have to do with it? It regulates the immune response, manages it, that is, it has the most direct relation to the inflammatory process that occurs in the body.

Although each of us is constantly threatened by harmful chemicals and pathogens, 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 does not function properly, even a simple mosquito bite can be deadly.

But if you do not take external events such as a mosquito bite, each part of our body is inhabited by pathogenic organisms that are potentially life-threatening, which, if not for the immune system, could very well have been fatal. It is important to understand that the immune system functions optimally when it is in balance.

Overactivity of the immune system can lead to complications such as allergic reactions, which in extreme cases are so intense that they can provoke anaphylactic shock, which can be fatal. In addition, if the immune system is impaired, it may cease to recognize normal proteins of its own body and begin to attack them. This is the mechanism by which autoimmune diseases occur.

The 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 manifests itself in a situation where 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 intestinal associated lymphoid tissue (CALT, or GALT). It accounts for 70–80% of the body’s immune system. This most eloquently speaks of the importance – and vulnerability – of our intestines. If what happens in it does not have such an important effect on human life, it would not be necessary for a significant part of the immune system to be located in the intestine, protecting the body.

The reason why most of the immune system is located in the intestine is simple: the wall of the intestine is the border with the outside world. Apart from the skin, it is here that the body has the highest probability of interaction with foreign substances and organisms. 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 maintain the integrity of this delicate intestinal wall, the thickness of which is only one cell. It should remain unharmed, despite the fact that it acts as a conductor of signals between the bacteria of the intestine and the cells of the immune system. In 2014, at a conference devoted exclusively to the topic of microflora, Dr. Alessio Fasano of Harvard University called these immune cells that receive signals from intestinal bacteria “the first response staff.” In turn, intestinal bacteria help the immune system remain “on guard”, but not in full protective mode.

They track the situation and “educate” the immune system, which helps to a large extent to prevent its inadequate response to food and provoke an autoimmune response.

Scientific studies both in animals and in humans have proven that “bad” or pathogenic bacteria can cause the development of the disease, but not only because they are associated with a certain condition.

For example, infection with the Helicobacter pylori bacterium is known to cause gastric and duodenal ulcers. However, as it turned out, this pathogenic bacterium also interacts with the intestinal immune system, causing the production of inflammatory molecules and stress hormones, as a result of which the stress response system switches to a mode of operation in which the body behaves as if it had been attacked by a lion.

Recent scientific evidence also suggests that “bad” bacteria can change the body’s response to pain: in fact, in people with unhealthy intestinal microflora, the pain threshold can be reduced.

The “beneficial” intestinal bacteria do the exact opposite. They try to minimize the number and consequences of their “bad” brothers, and also positively interact with both the immune and endocrine systems. Thus, beneficial bacteria are able to “turn off” this chronic reaction of the immune system. In addition, they help to control the level of cortisol and adrenaline, two hormones associated with stress that can cause a significant blow to the body if they are constantly produced there.

Each large group of intestinal 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 intestine, which account for more than 90% of the population of all intestinal bacteria, are Firmicutes and Bacteroidetes.

The bacteria of the Firmicutes group are known as “fat lovers,” since it is proved that the bacteria in this group have more enzymes to break down complex carbohydrates, that is, they are much more effective in extracting energy (calories) from food. In addition, it has been relatively recently discovered that they play an important role in increasing the absorption of fats.

According to research results, people who are overweight have a higher level of Firmicutes bacteria in the intestinal microflora than thin people who predominate in the Bacteroidetes group of bacteria. In fact, the relative ratio of these two groups of bacteria, Firmicutes to Bacteroidetes (or the F / B ratio), is a critical indicator for determining the health and risk of disease. Moreover, as it has recently become known, a higher level of bacteria Firmicutes actually leads to the activation of genes that increase the risk of obesity, diabetes and even diseases of the cardiovascular system.

Just think: changing the ratio of these bacteria can affect the expression of your DNA! The two best-studied bacterial species today are Bifidobacterium and Lactobacillus. Do not worry about how to remember these tricky names. In this book you will find more than once the complex Latin names of bacteria, but I promise that by the end of the reading you will easily begin to navigate in bacteria of various genera.

Although so far we cannot accurately state what kind of bacteria and in what proportion determine the optimal state of health, according to the accepted opinion, the most important is their diversity. It should be noted that the line between “beneficial” and “harmful” bacteria is not as clear as you might think. I repeat that important factors here are the general diversity and the ratio of different genera of bacteria relative to each other. With the wrong ratio, some genera of bacteria that can have a positive effect on the state of health of the body can turn into harmful ones.

For example, the infamous 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 a peptic ulcer, 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 serious infectious disease if its population in the body becomes too high.

The disease, the main symptom of which is severe diarrhea, still leads to the death of almost 14 thousand Americans annually. C. difficile infection has risen sharply over the past 12 years. In the period 1993-2005, the number of diseases among the hospitalized adult population increased three times, and in the period 2001-2005 – twice.

In addition, mortality has risen sharply, mainly due to the appearance of a mutated super virulent species of this bacterium. Usually, we all have a large number of C. difficile bacteria in our intestines in our intestines, and this is not a problem.

This bacterium is found in the intestines in approximately 63% of newborns and in one 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 too rapid an increase in the number of this bacterium, which can lead to the development of a deadly disease.

The good news is that today we know an effective way to treat this infection – using bacteria of other genera to restore the balance of intestinal microflora. Published by If you have any questions about this topic, ask their specialists and readers of our project here.


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