A Japanese scientist explains the relationship between the brain, the intestines, and the human health condition
Humans have always felt, on some level, a connection between the mind and the organs of the digestive system. English speakers use the phrase “gut feeling” for a gut feeling or hunch (gut means gut) and for “having butterflies in the stomach.” In Japanese, the feeling of overwhelming anger is referred to as “hara no moshi (literally an insect in the gut)” and painful sadness as “dancho no omoi (with chu meaning gut).” It is only fairly recently, however, that science has begun to shed light on the mechanisms underlying this association. Professor Fukudo Shin is a leading expert on irritable bowel syndrome and is among those pursuing the brain-gut connection to benefit human health.
“Medical science has for a long time treated the brain as the supreme organ, while the gut, the lower part of the digestive system, has been viewed as a peripheral organ for the last stage of digestion and excretion,” says Fukudo. But we have learned that there is a close two-way connection between the brain and the digestive system, especially the intestines.” Anything that disrupts or distorts this connection—from emotional stress to an imbalance of gut bacteria—can lead to a variety of physical and psychological ailments.
“We need to rethink our basic assumptions about the relationship between the brain and the gut,” says Fukudo.
Irritable bowel syndrome as a disorder of the brain-gut relationship
The brain and intestines communicate through the endocrine system, the autonomic nervous system, which includes the sympathetic and parasympathetic nervous systems, and the enteric nervous system. The vagus nerve, part of the parasympathetic nervous system, may be the most important link between the gut and the brain. Fukudo's research focuses on how psychosocial stress can affect the transmission of these gut-brain signals.
Fukudo was one of the first researchers to conceptualize irritable bowel syndrome as a disorder of the brain's interaction with the gut. Patients with Irritable Bowel Syndrome suffer from an intermittent disorder of the gut that manifests itself as diarrhoea, constipation, bloating and abdominal pain, which can seriously affect their quality of life. However, clinical examinations and tests do not usually show severe intestinal inflammation or other bowel abnormalities.
“Irritable bowel syndrome affects the gut, but it is also a stress-related disorder,” says Fukudo. It is prevalent mostly in advanced industrial societies. It is estimated that around one in ten people in Japan suffers from Irritable Bowel Syndrome.”
Unsurprisingly, Fukudo found that depression and anxiety had a higher incidence of depression and anxiety among people with IBS or IBS symptoms compared to those without gut complaints. According to Fukudo, patients with irritable bowel syndrome also tend to share certain personality traits, such as a tendency to be depressed or anxious. Moreover, they often have difficulty expressing their feelings, which can lead to a build-up of stress. Stress triggers the release of hormones that can increase gut motility and visceral sensitivity, leading to symptoms of irritable bowel syndrome.
The “second brain” and the microbiota
While Fukudo's work centers on the role of psychosocial stress in irritable bowel syndrome and other disorders, he is quick to point out that the brain-gut interaction is not a one-way street. The gut is never a subordinate organ, subject to the orders of the brain, as it can make its own decisions. About 90% of the signals transmitted by the vagus nerve travel from the gut to the brain. The state of our gut, including the state of our gut microbiota, can influence our moods, preferences, and behavior.
The latest scientific discoveries indicate that the diverse microorganisms that live in the gut play an essential role in the communication that takes place between the gut and the brain. Indeed, its function is so important that many now speak of an “axis of gut microbes, the gut, and the brain.”
Our bodies are an interconnected, interacting community of human cells and microorganisms. Tremendous advances in the field of DNA over the past two decades have allowed scientists to better quantify and quantify the diversity of organisms that make up the human microbiome (the total number of microorganisms in the body). The average adult human body contains more than 100 trillion microbes representing approximately 1,000 species of bacteria. There are about 90% of these microbes in the cells and mucous membranes of the intestine. When we are infants, our bodies contain some of the microbiota that we inherited from our mothers when we came into this world through the birth canal, and we also ingest more of them through breast milk. Over time, the gut microbiota continues to diversify over the next few years, stabilizing by the time we are about three years old.
The gut, aided by the community of gut microbes, produces a variety of chemicals known to influence mood and cognition, as well as gut-brain communication. In fact, more than 90% of the body's serotonin—an important neurotransmitter and mood regulator—is secreted into the gut with the help of microbes. And our gut microbiome, through signals sent to the brain, influences what foods we like to taste and how much we eat. The latest research indicates that when bacteria multiply
Keeping the brain-gut connection intact
So how does one keep the brain-gut axis healthy?
It starts in the gut. Fukudo recommends a diet high in fiber and low in refined carbohydrates and additives, with an emphasis on fresh fruits and vegetables and fermented foods. He has personally witnessed cases where a change in diet completely turned things around.
Many medications can upset the normal microbial balance of the gut. And Fukudo warns against the overuse of antibiotics in particular.
He also stressed the importance of eating a good breakfast every day to support regularity. “I know there are a lot of kids who skip breakfast, so that their bowels don't move while they are at school. Teachers need to adopt a healthier attitude towards normal bodily functions such as bowel movement, so that children are not embarrassed about it.” Other habits that support a healthy brain-gut axis are adequate sleep and rest and regular exercise.
Based on his own experience, Fukudo believes that the most important thing one can do to prevent and relieve IBS is to identify the sources of stress in daily life and talk to others about them rather than suppressing them. From this perspective, cognitive behavioral therapy has great promise as a tool for alleviating symptoms of gut problems and improving the overall quality of life. Ultimately, an integrated mind-body treatment may make more sense for a brain-gut axis disorder.
The symptoms of Irritable Bowel Syndrome are real and sometimes debilitating. But until recently, people suffering from these symptoms could expect little sympathy or understanding, let alone effective treatment. Today, however, there is new hope for irritable bowel syndrome and many other difficult-to-treat conditions, thanks to the tremendous advances in science dealing with the interaction between the brain and the gut.
Source : nippon