Trillions of bacteria live in the human gut, particularly the large intestine. The microorganisms, which include probiotics and prebiotics, make up the natural gut flora, sometimes called the microbiome. A healthy microbiome is extremely useful for the body: the intestinal bacteria help to digest food components, prevent pathogens from spreading in the intestine and contribute to the functioning of our immune system. In addition, the intestinal flora stimulates intestinal movements and produces vitamin K, which is important for blood clotting.
Whether changes in the intestinal flora can cause diseases such as irritable bowel syndrome, Crohn’s disease or ulcerative colitis has not yet been fully clarified scientifically. There are studies that show that the intestinal flora of irritable bowel patients differs significantly from the microbiome of healthy people. However, it is unclear whether this change is the cause or consequence of the disease. What is clear, however, is that stress or taking antibiotics can imbalance the intestinal flora. And that a disturbed balance of the intestinal bacteria – such as an overgrowth in the small intestine – can lead to massive health problems.
Probiotics: Health-promoting microorganisms
A positive effect on intestinal flora is mainly attributed to the so-called probiotics. “The probiotics are, so to speak, desired inhabitants of our intestines,” explains nutrition Doc Jörn Klasen. “These bacteria – sometimes also yeast – can help to strengthen the barrier function of the intestine and keep pathogens in check.” Some of them produce valuable substances – short-chain fatty acids such as butyrate or propionate, for example, which, according to studies, help to keep nerve cells healthy, among other things. The microorganisms occur naturally in lactic acid products such as yogurt, kefir, and buttermilk, but also in preserves such as sauerkraut, pickles, or kimchi. There are also probiotics in capsule and drop form that are used as medicines and are often available without a prescription.
The effect of probiotics depends on the clinical picture
A prerequisite for a health-promoting effect of probiotics is that the bacteria and yeast are used to get to where they are supposed to. This means that they must be present in the food or drug in sufficiently large quantities, they must survive the passage through the stomach and small intestine and prevail against the bacteria that predominate in the large intestine. In addition, the effect of the bacteria depends on the clinical picture and the strain of bacteria used, it cannot be generalized. For example, there is a probiotic drug made from the E. coli strain Nissle 1917 that is used to treat childhood diarrhea and ulcerative colitis. In any case, probiotics should be consumed regularly – according to studies daily and for weeks – so that they have a positive effect on intestinal flora.
“In healthy people, however, a balanced diet with vegetables and whole-grain products is usually enough to keep the microbiome in balance,” says nutrition doc Matthias Riedl.
Many vegetables contain prebiotics
In addition to probiotics, prebiotics also has a health-promoting effect on the intestine. Unlike probiotics, however, they are not microorganisms, but dietary fibers that are not digested by the body. They include plant compounds such as inulin and oligofructose. Some of the “good” bacteria in the large intestine pounce on the prebiotics, use them preferentially, and can multiply as a result. “Prebiotic foods ensure that bifidobacteria, in particular, feel comfortable in our intestines,” says nutrition doc Anne Fleck. “Bacterial strains that cause diseases, such as clostridia and certain types of E. coli, then have a harder time spreading through the intestines.” Prebiotics also help with constipation, diarrhea, and constipation.
Many foods contain healthy fiber
Some food manufacturers add prebiotics to products such as baked goods, fruit juices, and sausages to make them richer in fiber and therefore “healthier”. Nature actually provides us with enough: Prebiotics are contained in chicory, Jerusalem artichoke, onions, garlic, black salsify, artichokes, and bananas, for example. According to studies, however, a quantity of around five grams per day is necessary for prebiotics to be effective. This means for the menu: several portions of vegetables – for example as a salad, side dish, soup or juice.