Intestinal flora


The term intestinal flora (Microbiota, microbiome of the intestine) refers to all microorganisms that colonize the human intestine. That's up to 99 percent of all bacteria that live in and on the human body. Read about the various intestinal bacteria, their tasks and health problems that affect the intestinal flora!

Article overview intestinal flora

  • What is the intestinal flora?
  • What is the function of the intestinal flora?
  • Where is the intestinal flora?
  • What problems can the intestinal flora cause?

What is the intestinal flora?

The intestinal flora is the totality of all intestinal bacteria that colonize parts of the human large intestine (in a small amount also the rectum). The term gut flora comes from the earlier assumption that this accumulation of microorganisms belongs to the plant kingdom. But as the bacteria belong to a separate kingdom (Protista), the term gut bacteria, intestinal microbiome or intestinal microbiota is the better term.

The majority of intestinal flora - more than 400 different intestinal bacteria species - lives in the colon (on the intestinal wall). Their number is estimated at about 10 trillion, their total weight to about one and a half kilograms.

Intestinal flora: enterotypes

Depending on the dominant bacterial strain, there are roughly three different types of intestinal flora, so-called enterotypes (from Latin entero = intestine):

  • Enterotype 1: contains particularly many bacteria of the genus Bacteroides, which split carbohydrates and are good producers of the vitamins biotin, riboflavin and pantothenic acid
  • Enterotype 2: contains especially many bacteria of the genus Prevotella, which can break down sugar-protein complexes and produce vitamin B1 and folic acid
  • Enterotype 3: contains particularly many Ruminococcus bacteria, which are able to digest sugars and proteins very well

Experts discuss whether the composition of the intestinal flora can be specifically and permanently influenced by the type of diet (fiber content, etc.).

Development of intestinal flora in children

The intestine of a still unborn child is still completely sterile. Only with the birth process begins its colonization with microorganisms: bacteria of the maternal intestinal flora get in a natural (vaginal) birth through the baby's mouth in the gastrointestinal tract, where they build the child's intestinal flora and gradually form a stable microbiome.

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What is the function of the intestinal flora?

The vital intestinal flora fulfills various tasks:

The intestinal bacteria support digestion. They produce short-chain fatty acids such as butyrate, acetate and propionate from indigestible dietary fiber. These cover a large part of the energy requirement of the colon mucosa. In addition, the short-chain fatty acids promote the intestinal musculature and play an important role in the mobility of the intestine (intestinal motility).

The intestinal flora produces various vitamins that the body can use for itself (even if only a small part of it can be absorbed in the large intestine). These include biotin, folic acid and vitamins B2, B12 and K.

Some intestinal bacteria can neutralize toxic (toxic) substances, such as nitrosamines and polycyclic aromatic hydrogens. Many of these compounds are considered carcinogenic.

Some medications are converted into their active (effective) form only during the metabolism through the intestinal flora. This applies, for example, to antibiotics from the group of sulfonamides and to the anti-inflammatory drug sulfsalazine.

The intestinal flora is extremely important for the immune defense. The intestinal mucosa has a surface area of ​​300 to 500 square meters and thus represents the largest interface of the body. The "good" intestinal bacteria settling here prevent disease-causing germs from spreading and causing intestinal infections. In addition, the intestinal bacteria train via special signal structures in the gut localized part of the immune system (intestine-associated immune system)

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Where is the intestinal flora?

The intestinal flora colonizes especially the colon (colon). Small intestinal bacteria are also found in the rectum (rectum).

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What problems can the intestinal flora cause?

As long as the intestinal flora bacteria remain in the gut, they are generally harmless. However, if they get into other organs (for example, into the blood or into the vagina of women), they can cause disease.

The colonization of the small intestine with intestinal bacteria is low. This is to avoid nutrients from the diet, such as vitamin B12, being metabolised by intestinal bacteria instead of being absorbed into the body via the small intestinal mucous membrane. If, however, by surgery, for example, blind-ending intestinal loops are present, the bacterial density in the small intestine can rise so much that caused by the vitamin B12 deficiency anemia.

If medication inhibits the release of gastric acid (for example, heartburn or gastritis), it may interfere with the composition of the intestinal flora over time.

The administration of antibiotics can also confuse the human microbiome. It can then be inhibited in their growth and promote others in their growth individual intestinal bacteria species. The balance of the intestinal flora is lost. The result may be mild symptoms such as diarrhea, but also severe inflammation in the colon.

If the Bifidus and Bacteroides intestinal bacteria, which synthesize the vitamin K, which is important for blood coagulation, are damaged by medication, blood clotting can be disrupted.

Coadministration of antibiotics and anticoagulants (blood thinners) may cause severe bleeding.

The composition of the intestinal flora influences the occurrence of colon cancer and other diseases. With probiotics, many people take targeted "good" bacteria for the intestine (such as lactic acid bacteria) to strengthen their intestinal flora, such as diarrhea. Supplied in sufficient quantities, probiotics can actually prevent rotavirus diarrhea and help with diarrhea caused by radiotherapy or antibiotics. However, the bacteria supplied as probiotics settle only on regular intake in the intestinal flora. If the intake ends, they disappear again and it turns over again the "old" intestinal flora one.

"We are puppets of our intestinal microbes." Trillic microbes cavort in the intestines of every human being. Their influence reaches into the brain. What effect does that have on the human psyche? From EXPERIENCE MORE!