In humans, the gut and brain are connected via the enteric nervous system (relating to the small intestine). It's no wonder, then, that they interact. The enteric nervous system transmits information between the brain and the digestive tract via millions of nerve cells. The beneficial and important bacteria in the digestive tract are key components in converting fiber, i.e., poorly digestible foods, into usable nutrients. The majority of these bacteria in the human body are found in the large intestine.
The literature often cites studies claiming to demonstrate that a large number or abundance of good bacteria also offers resistance to psychological stress. Among other things, this is due to the production of neurotransmitters. These serve to transmit signals in the nervous system. The so-called gut-brain axis, with the vagus nerve as the main link, establishes a connection between stress and emotions, which affect digestion, and vice versa. This is the view of biochemist Dr. S. Pival-Marko1. According to this axis, spicy and fatty foods should be avoided, especially during "stressful times." Probiotics are recommended to maintain the immune system, which counteract the development of systemic inflammation in the body and balance serotonin levels in the brain. These probiotics contain microorganisms that enable the gut to regenerate itself (flora). Antibiotics and other medications also harm beneficial bacteria, as well as the liver. A healthy intestinal flora is the basis for balance.
Although a majority of respondents in Germany alone expressed doubts about the effectiveness of probiotics, the general business with dietary supplements is booming. After all, 14 million people report using these or other dietary supplements daily. It is therefore not surprising that, on the economic side, there are clear increases in global consumption, especially of digestive aids. The expected sales figure for 2025 is set at €8.24 billion; by 2029, this figure is expected to reach €10.57 billion, corresponding to sales growth of over 6% per year. Staying fit despite stress with dietary supplements? In the Federal Republic of Germany, sales of dietary supplements amounted to €2.3 billion, approximately 54% of which were vitamins and minerals.
As tempting as these figures may be for industry and entrepreneurs, in the author's opinion, consumers should maintain a healthy skepticism. A healthy diet rich in vegetables and fruit remains the best source of vitamins and minerals. A natural product made from fermented bread, known as "bread drink," is said to offer an alternative for the intestinal flora. Numerous types of tea are also available to promote health and digestion. These are also said to be significantly healthier for the liver and intestines.
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Stange, Rainer | Leitzmann Claus: Ernährung und Fasten als Therapie, 2. Auflage, Springer Verlag, 2018. (German)
Reuter, Peter: Medizinisches Wörterbuch, Springer Verlag, 2005, Begriffe "Neurotransmitter", "enterisch". (German)
Magazine: Welt der Wunder, Article "Wunderwelt der Bakterien", Ausgabe 12/24, S. 92-93 (German)
Statista researche department in evaluation: "Barrieren bei der Nutzung von probiotischen Produkten in Deutschland 2018". (German)
Statista researche department in evaluation: "Anzahl der Konsumenten in der Kategorie 'Vitamine und andere Nahrungsergänzungsmittel (einschließlich Sporternährung/Ergänzungsmittel und Probiotika)' nach Häufigkeit in Deutschland im Jahr 2023 ". (German)
Statista researche department in evaluation: OTC Pharma "Verdauungsmittel - Weltweit" (German)
Statista researche department in evaluation: "Umsatzverteilung bei Nahrungsergänzungsmitteln nach Produktgruppe 2020 ". (German)