Are hygiene craze and poor nutrition causing the microbiome to shrink?

There is a surprising amount going on in the body. Billions of germs roam around there. Bacteria, fungi, protozoa: every human being is a carrier of at least 1000 different species. The tiny microorganisms colonize the intestines, but also the skin, nose, mouth and genitals. This is by no means disgusting or even harmful, as we know today. Rather, these germs, also known as the microbiome, keep us healthy. But there’s a problem.

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“Probably about half of the microbiome in Western countries has been lost,” says Till Strowig, who studies the protective effect of bacteria in the gut flora at the Helmholtz Center for Infection Research (HZI) in Braunschweig. The problem that researchers are increasingly pointing out is that many people are becoming more susceptible to disease due to the decrease in microorganisms.

A long list of popular ailments is suspected. Metabolic disorders, for example, which lead, among other things, to obesity. Heart and vascular disease can also be promoted. Likewise, chronic inflammatory bowel diseases such as Crohn’s disease and autoimmune diseases such as rheumatism. A connection between food allergies and the gut microbiome is also suspected. So why are microorganisms suddenly disappearing?

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Birth, breastfeeding, place of residence: the microbiome develops in infancy

The first five years of life are particularly crucial for the development of the microbiome.

Up to Strowig,

research the microbiome

It is the human being himself who increasingly pushes the protective germs out of his life, crossing everyday life in a more hygienic, sterile and urban way. On the one hand, this has advantages, as Strowig explains. Bad pathogens, such as cold, corona, noro and influenza viruses, are less likely to spread. But there are also disadvantages: good pathogens relevant to the microbiome no longer come into contact with the human body. Because it depends on the absorption of bacteria from the environment.

Especially in childhood. “The first five years of life, in particular, are crucial for the development of the microbiome,” says Strowig. Researchers know that babies born by caesarean section develop a different microbiome in the first few months than those born vaginally. When a baby passes through the mother’s birth canal, it ingests a large number of microorganisms for the first time. According to data from the Federal Statistical Office, however, around 30 percent of deliveries today end with a caesarean section.

Till Strowig heads the department of microbial immune regulation at the Helmholtz Institute for Infection Research. His team studies how microbial communities affect infectious diseases and how they can be manipulated to cure disease.

Is a baby breast or bottle fed? This also plays a role because breastfeeding transfers bacteria and components that nourish the young microbiome. There is really great progress in pre-food offerings. “But it’s still not the same when it comes to developing the microbiome,” Strowig says of the current state of the research.

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How children grow up also plays a role. “Anyone who grows up in a super sterile environment is less likely to ingest various natural bacteria,” says Strowig. A little contact with dirt in everyday life? It definitely has health benefits. Do children play with many different friends or always the same ones in the first years of life? Is their environment heavily sanitized with disinfectants? Are you growing more urban or rural? Have you been taking antibiotics for a long time? All this helps to decide which microorganisms colonize the body in the first formative period of life.

Better Whole Grains Than Chips: Today’s diet is lacking in fiber

When we eat high-fiber foods, we give bacteria more substance to grow.

But adults are also caught up in the fact that their microbiome is shrinking more and more these days. They eat less fiber than before, giving the good bacteria in the large intestine too little food. Instead, today’s diet means that mostly easily digestible foods are ingested. “However, many health-promoting bacteria feed on roughage, the components of our food that humans can’t digest well on their own,” says Strowig. “If we eat high-fiber foods, we give the bacteria more substance to grow.”

Conversely, this also means: The more varied and less processed food you eat, the more bacteria can find their niche in the body, and the microbiome can be supported for life. Instead of sweets, chips and frozen pizza, whole grain products, nuts, fruits, legumes like chickpeas, vegetables like celery, broccoli or even mushrooms should be on your plate. This is what the German Nutrition Society recommends.

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Microbiome destroyed: fecal donations could help

Because once the microbiome has been destroyed, there is no pill to favor a reset. After all, new therapeutic approaches are in the offing. Strowig reports that experiments in which healthy people donate stool samples, which are then transplanted into the diseased gut flora or given in capsules, are particularly promising.

Countries like the Netherlands have already had good experiences with such a treatment method. Recurrent infections with Clostridioides dificile, for example, could be stopped with the help of a stool transplant. It is an acute inflammation of the intestine that occurs mainly in elderly people or during a hospital stay, often after the administration of antibiotics. In Germany, people are even more hesitant than in the neighboring country. Treatment is not yet generally recommended, which has something to do with approval guidelines, Strowig reports. Clinical trials on stool transplants have increased but also in this country. Such approaches could also help in cancer therapy or diseases of the nervous system.

Be careful with stool tests from private providers

You cannot reliably tell by such tests whether this microbiome is good or bad for this person.

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Various private Internet providers have now broken through the hype surrounding stool transplants. They offer so-called gut microbiome analyzes. The promise? Anyone who submits a stool sample should obtain information on the exact connections between gut flora and health problems. Sometimes personalized nutrition advice is included. “I don’t recommend doing that,” says scientist Strowig. “You cannot reliably tell with such tests whether this microbiome is good or bad for this person.”

To better understand the interaction of bacteria, this is exactly what research is still working on. It has also not yet been precisely deciphered which fecal donation with which microorganisms might be particularly suitable for which patient. Here lies the big challenge: how microorganisms are composed and how they protect each other varies from person to person. Each microbiome is unique.

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