IThere’s a lot going on in the intestines: around 100 trillion microorganisms inhabit our interior. They result in what is referred to in medicine as the intestinal Microbiome. Exactly how it is made up varies from person to person. And our microbiome can change every day, for example through our diet.
Even if fungi, amoebas and other protozoa can be detected in the intestine in addition to viruses, bacteria play the most important role, says Tobias Goris. The biochemist conducts research at the German Institute for Human Nutrition in Potsdam-Rehbrücke, among other things, on human intestinal bacteria. Science today assumes that there are bacteria in the gut that are harmful to our health and others that are beneficial to it. “These are important for our immune system,” says Goris. They also play a major role in digestion. There are also bacteria that have an anti-inflammatory effect or have a positive effect on the metabolism. But: “All of this is complex and little researched,” says the biochemist.
Scientists agree that nutrition does something to the microbiome. Food with a particularly high fiber content, for example, has a positive influence, as Andreas Stallmach explains. He is a doctor and heads the Clinic for Internal Medicine IV at the University Hospital in Jena. Fiber is found in whole grain products, nuts and legumes, but also in fruit and vegetables. Stallmach has a tip for potatoes: If they are left to cool for 24 hours after cooking, their starch structure changes. This makes it particularly valuable for the microbiome in the intestine.
Fermented foods such as sauerkraut also have the reputation of being particularly valuable for the intestines. “But that’s not just due to the lactobacilli that develop during fermentation,” says Stallmach. The reason for the positive effect here is also the large amount of dietary fiber. According to Stallmach, products that are advertised as particularly probiotic are not necessary for intestinal health. They are especially good for the manufacturers, who earn a lot of money with them.
But not only food, fasting also seems to have a positive influence on our microbiome. That says Sofia Forslund from the Max Dellbrück Center for Molecular Medicine in the Helmholtz Association. She researches the connection between the Intestinal Microbiome and cardiovascular diseases.
In a study, she and other researchers were able to show that a five-day fast can have a positive effect on the intestinal microbiome. The renunciation of food changed the composition of the ecosystem of intestinal bacteria significantly – especially the health-promoting bacteria increased.
Little red meat or alcohol
Red meat and sausage, on the other hand, have a negative impact on the microbiome. Therefore, the consumption should be 300 to 500 grams per week, according to Stallmach. The same applies to alcohol: only in moderation.
Goris from the German Institute for Human Nutrition Potsdam-Rehbrücke adds: “Less variety in nutrition means that there is more breeding ground for more harmful bacteria.” To worry. Differences would be particularly noticeable when people eat extreme diets: “If I only eat fast food for 20 years, you can see that the microbiome in the intestine is less diverse and some bacteria are also completely lost.”
Not only the diet, but also the repeated intake of antibiotics change the intestinal microbiome. The medicines are designed to destroy pathogens in the body. However, they also kill beneficial bacteria in the gut. Stallmach therefore criticizes the use of antibiotics in Germany: “There are still too many antibiotics prescribed that are too uncritical.”
Sofia Forslund from the Max Dellbrück Center examined the connection between antibiotics and the intestinal microbiome. After the administration of an antibiotic, everything was usually back to normal after six months at the latest. In some cases, however, the variety of intestinal bacteria was no longer as great as before the intake. The microbiome can change in the long term, especially when antibiotics are administered multiple times and over a longer period of time.
The result of a long-lasting bad diet or the intake of antibiotics can be a so-called dysbiosis. This means that the colonization of the intestine with beneficial bacteria is disturbed. Researchers suspect that the intestinal microbiome has an influence on many diseases. Often, however, the connection has not yet been proven beyond doubt, says the doctor Stallmach. However, studies have already shown that dysbiosis is a risk factor for the development of colon cancer or chronic inflammatory bowel diseases Crohn’s disease.
“We also see an association between a less diverse gut microbiota and overweight. This also applies to the associated diseases such as the metabolic syndrome or diabetes.” But it is not yet possible to say whether it is a direct effect – or whether both often occur together.
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