When your gut affects your psyche

Whether or not they hugged each other with joy is simply an assumption: the neurologists and gastro-intestinal specialists would certainly have had good reason to do so when they were able to prove several years ago that the gut and brain are closely connected with each other – much more closely than long thought. How exactly and why the two organs affect each other has not yet been determined. However, it is clear that with this result, the researchers have laid an important foundation for the future.

The finding on the gut-brain connection is a revolution, also for psychiatric research. This is because for a long time, the basic sentiment was that everything is controlled by the brain. All unclear medical complaints in the human body were attributed to a conflict in the mind. “For a long time, the gut was misunderstood as being a hard-working servant of the digestive tract and an annoying alarm system for mental conflicts,” says the psychiatrist, Gregor Hasler. He adds that more recent studies have now debunked this theory. He states that the result of the investigation showed that the flow of information from the gut to the brain is actually even greater than vice versa.

In order to better understand the connection between the two organs, it is worth having a look inside the gut. Its specifications are certainly nothing to sneeze at: as the largest organ in the human body, it has a huge surface area of about 300 to 500 square metres, making it bigger than a basketball court. The reason for this incredible area is the countless tiny folds and villi in the intestinal wall. Just as impressive but considerably more relevant are its inhabitants.

“More bacteria, viruses and fungi live on a single square centimetre than the total number of humans on Earth,” says Hasler. The sum of all these inhabitants is the intestinal flora. This also includes all unpleasant inhabitants which produce toxic substances and thus cause diarrhoea and stomach complaints, for example. However, the majority of intestinal bacteria are hard workers. With their permanent deployment, they are part of our immune system and protect our body against illnesses.

The principle of coexistence applies in the intestinal flora. Certain unpleasant inhabitants are tolerated. However, if their numbers get out of hand, problems start which can ultimately affect the immune system, but this also already manifests itself when our good bacteria go on strike.

This happens, for example, after a big fatty meal when they make us feel tired and lacking in concentration. The information concerning the striking bacteria travels from the gut to the brain. Both organs exchange lots of information with each other, largely communicating via nerves, hormones and inflammatory substances. The latter are so-called cytokines. Research refers to a gut-brain axis.

Hormones are an important component of this gut-brain axis, particularly where our mental state is concerned. More recent studies have shown that we have our gut to thank for 95 per cent of the happiness hormone serotonin and not our brain. If this production is disturbed, this results in sleep problems, anxiety or depressive moods.

So the greater the damage to the intestinal flora, the more mental well-being can suffer from it. Accordingly, our eating habits could play an important role where our psyche is concerned. According to Hasler, an initial study has proven that a Mediterranean diet could produce an antidepressant effect, especially in people whose diet centres around fast food.

“It is certain that there is an impact on the psyche,” emphasises Hasler. He says that further research results are required in order to determine how great it actually is. One of the biggest challenges in this respect involves finding out what came first. For instance, based on the example of depression: what caused it? The disturbed intestinal flora or the depression itself which has a negative impact on the gut?

Another hot topic in psychiatric research is how important the gut-brain axis could be for other treatments. In addition to treating depression, scientists see great potential for alleviating illnesses like autism, attention deficit hyperactivity disorder (ADHD) or dementia. According to Hasler, researchers have made surprisingly great progress in this area in recent years. So it is quite possible that the next breakthrough will already be announced soon.

“I have been occupying myself with the gut ever since I hit puberty,” says Gregor Hasler. He also reports on memories like this one in his book entitled “Die Darm-Hirn-Connection” (The Gut-Brain Connection), which was published in 2019. He says he has first-hand experience of intestinal problems. All the melancholic moods and romantic ecstasy which he felt were accompanied by cramps, flatulence and other stomach problems. Haslers moods disappeared over time, not least because his suffering became his vocation. Hasler now works as a Professor of Psychiatry at the University of Fribourg and is optimistic where his area of research is concerned: “We can prepare ourselves for an exciting time in which the gut and brain will be closer to each other than ever before.”