How stress affects gut health


It has long been known that stress can affect digestion. Researchers have now discovered which mechanisms in the body are responsible for stress-related intestinal diseases.
By Katharina Ditschke and Ralf Kölbel, SWR

In Germany, more than 320,000 people suffer from chronic inflammatory bowel diseases (IBD) such as Crohn’s disease or ulcerative colitis. Ascending trend. Typical symptoms: bouts of severe abdominal cramps, diarrhea and fever. In some people, the disease is mild, in others so severe that it can even be life-threatening.Chronic psychosocial stress can weaken the gut’s immune system, a 2020 study shows. This promotes inflammation and creates an unhealthy environment in the intestine.Researchers from the USA have now decoded the mechanism of how stress affects the intestines. This could also explain why some therapies have so far not had the desired success.

Psychological factors are often ignoredInflammatory flare-ups in people with inflammatory bowel disease are usually treated with cortisone, which is intended to reduce acute inflammation. If those affected no longer react to cortisone, so-called biological drugs are administered. These are antibodies that are said to have the ability to stop the inflammatory process. But one aspect has been neglected for a long time, says Christoph Thaiss, microbiologist at the University of Pennsylvania in Philadelphia on SWR : During the investigation, he and colleagues repeatedly found that patients who complain about stressful life situations such as separation from their partner or the death of a partner Family members complained that they had significantly stronger parameters of intestinal inflammation.


The brain sends signals to the adrenal glands when it is stressedThaiss and his team took this feedback as an opportunity to investigate more closely how psychological status and stress factors affect intestinal diseases. Together with the team of microbiologist Maayan Levy, also from the University of Pennsylvania, the researchers first examined what happens when signals are sent to the brain under stress.In animal experiments with mice, the researchers found that the brain sends signals to the adrenal glands after a stress wave. The adrenal glands secrete their own cortisone (glucocorticoids). First of all, it has analgesic and anti-inflammatory properties.”The body reacts to stress and releases glucocorticoids as stress hormones. And they then acutely suppress the immune response,” explains microbiologist Thaiss. “This means that the inflammation is acutely dampened. Chronic stress, however, leads to an increase in the inflammatory reaction.”

Stress hormones are passed on to immune cellsThe researchers initially assumed that the glucocorticoids have a direct effect on immune cells. However, it turned out that there is a kind of interface that transmits stress signals to the immune response: so-called glial cells.These cells have an important function for the motility of the intestine. These processes are also controlled by neurons located in the intestinal wall. The gut is the only organ outside of the brain that has its own nervous system.Stress affects gut musclesThe involuntary movements of the circular and longitudinal muscles normally transport the chyme through the small and large intestine towards the rectum. The researchers have now discovered that glial cells and neurons located in the intestinal wall can recognize and respond to stress molecules. This in turn affects the immune response in the gut. If the glial cells notice in the environment over a long period of time that stress hormones (glucorticoids) have settled in the intestine, they begin to produce pro-inflammatory molecules. These in turn activate immune cells in the intestine. This intensifies the inflammatory reaction of the intestine.On the other hand, neurons in the gut also respond to glucorticoids and lose their ability to regulate muscle. Food stays in the gut longer. These two phenomena contribute to the aggravation of intestinal diseases.
A girl sits on the banks of the Elbe and looks into the distance.

Walks, yoga and meditation to relieve stressResearchers are now considering two ways they can better help people with chronic bowel disease in the future. Expert Thaiss recommends reducing stress as the first measure. This is to prevent the inflammation from getting worse. The researchers are also working on the question of whether the glial cells, which research has identified as important factors for intestinal health, can also be used therapeutically – i.e. which drugs could have an effect on the pro-inflammatory molecules.As long as this question remains unanswered, experts recommend various methods to reduce stress. This includes getting enough sleep and regular exercise — 30-minute walks about three times a week. Relaxation exercises such as yoga, meditation and autogenic training can also help to reduce stress.