How probiotics help against irritable bowel syndrome

People with irritable bowel syndrome experience indigestion. Experts see therapy with probiotics as an opportunity to restore balance in the intestines

For Martin Storr, irritable bowel syndrome is like a puzzle that is still missing important pieces. Peter Layer likes to compare the disease to a building with many unopened doors. Both professors want to express the same thing: Irritable bowel syndrome is still a mystery to doctors.

An estimated four to ten percent of the German population torment themselves with recurring diarrhea, cramps, constipation and flatulence. Often the symptoms are so bad that your own digestion dictates the daily routine.

What role do gut bacteria play in irritable bowel syndrome?

Doctors can clearly diagnose the condition, but so far only know a part of its triggers - such as genetic predisposition, stress, psychological stress, infections or the use of antibiotics. This variety of causes makes therapy difficult and often results in a treatment marathon for patients. Because what helps one often has no effect on another.

"A lot of research will be needed before we have a complete picture of this disease," says Layer, medical director of the Israelite Hospital in Hamburg. For some time now, this research has been focusing on what is perhaps the largest living community in the world: our microbiome.

This is understood to be the 100 trillion bacteria that live on and in an adult. They cavort, for example, on our skin and mucous membranes, in the mouth, stomach and intestines. Bacteria feel particularly at home in the large intestine, up to 1400 different species colonize its mucous membranes.

If the intestinal flora is out of balance, health suffers

It is quite possible that the tiny organisms actually represent an important piece of the puzzle or a newly opened door for irritable bowel researchers. Because contrary to what has long been thought, the bacteria are by no means only responsible for our digestion. New findings show that they have a variety of tasks in the body and play a role in countless processes. Apparently they not only influence our psychological well-being, body weight and the immune system, but also the development of certain diseases. For example, a connection with depression, rheumatism, diabetes, multiple sclerosis and irritable bowel syndrome is being discussed.

In any case, it seems clear that if the microbiome is out of balance, health suffers. Science is only just beginning to discover how far the connections actually go.

"I am convinced that the microbiome plays an important role for irritable bowel patients," says Expert Layer. The number of studies on this topic has multiplied in recent years, and new findings are constantly being added. Layer: "We can state that the symptoms of irritable bowel syndrome can in many cases be influenced by the intestinal flora."

Intestinal flora changed in irritable bowel patients

It has meanwhile been proven that the stool and intestinal flora of irritable bowel patients differ significantly from those of healthy people. For example, so-called Proteo and Firmicutes bacteria occur more frequently, while the number of Acinetobacter, Bacteroides and Bifido bacteria is reduced.

All of this indicates a disorder in the gut microbiome. However, it is not yet known whether this is a cause or a consequence of the suffering."In any case, it is an important adjustment screw for the disease," says Professor Martin Storr from the Center for Endoscopy in Starnberg.

Probiotics show positive effects

The best way to turn this screw is with probiotics. This is the name given to living bacteria and yeasts found in lactic acid products such as yogurt, kefir or buttermilk. They belong to the health-promoting microbes and help to strengthen the intestinal barrier and keep pathogens that cause illness at bay. So are the good old lactic acid bacteria the solution for those with irritable bowel syndrome?

"Probiotics have a variety of effects in the body. For example, they inhibit the growth of harmful germs and their adhesion to the intestinal mucosa, relieve inflammation, strengthen the immune system and improve intestinal movement," explains Layer, who himself has carried out several studies on the subject and of the positive effects is convinced.
And he is not alone in this: as early as 2011, the German Society for Gastroenterology, Digestive and Metabolic Diseases (DGVS) included therapy with probiotics in its guidelines for the treatment of irritable bowel syndrome.

Eating yogurt is not enough

What does this mean for patients? Eating more yogurt or consuming specially fortified drinks is not enough. With the few million bacteria it contains, the intestinal flora can hardly be impressed. "For therapeutic purposes, higher doses are needed so that enough living bacteria can get into the intestines," says Storr.

The choice of the bacterial strain is also decisive. According to the guidelines, Bifidobacterium infantis and Lactobacillus casei Shirota help against flatulence, while E. coli Nissle has proven itself in constipation and lactobacteria attack in diarrhea. "It can happen that you have to try out what helps, one after the other," explains Layer.

In general, this therapy requires patience. It usually takes several weeks for the effects to occur. This only lasts as long as you ingest the bacteria. And no one can predict whether a probiotic treatment will really work. Layer: "Probiotics have enormous potential. But for some patients they are still completely ineffective."

Why this is so is just one of many open questions: Do probiotics work better when combined with fiber? Does it help to change my diet at the same time? Should you take probiotics as capsules or should you spray them directly onto the mucous membrane after an intestinal irrigation? "There has to be much more specific research," says Storr.

Is the stool transplant an option?

As one of the first doctors in Germany, Storr also works with fecal microbiome transfer, better known as stool transplantation. Here, prepared stool from a healthy donor is introduced into the recipient's intestine in order to create a healthy bacterial environment there. Sounds a bit gross, but it's effective - at least with a certain infection. So far, however, it does not look as if this method will catch on with irritable bowel patients. "At the moment this is more of an option for individual cases where nothing else works," says Storr.

For everyone else, a serious attempt with probiotics is worthwhile - i.e. with the right strain, over a longer period of time and in sufficient dosage. There are no side effects worth mentioning, it is easy to take, and the therapy can be combined with other measures if necessary.

"We opened this door, but so far only shone it with a flashlight. We see a long hallway with many doors leading off. There is a lot to discover behind it," says Layer.