Probiotics are living microorganisms – often lactic acid bacteria or bifidobacteria – that are found in yoghurt, fermented foods or as a dietary supplement. They can have a positive influence on the balance in the intestine and thus improve the intestinal barrier strengthen the intestinal barrier. This barrier acts like a protective shield that lets nutrients in but keeps harmful substances and pathogens out.
The study explains how probiotics work:
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They stimulate the formation of mucilage which protect the intestinal wall.
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They promote the production of antimicrobial substanceswhich inhibit harmful germs.
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They influence the tight junctions – the “seals” between the cells – and make the intestinal wall less permeable.
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They train the immune systemso that it reacts appropriately but not excessively.
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They promote the formation of short-chain fatty acids from dietary fiber, which have an anti-inflammatory effect.
A healthy intestinal barrier not only protects the digestive tract, but also has a positive effect on the entire body – for example on the immune system, metabolism and even the nervous system.
Conclusion: Probiotics can help stabilize gut health and prevent disease. However, the effect strongly depends on the type of bacteria, the dose and the person’s state of health. Further research is therefore needed before clear recommendations can be made for all people.
Background
The intestinal barrier represents the first line of defense between the intestinal lumen and the organism. It consists of a mucus layer, epithelial cells with tight junctions and immunological components. An intact barrier regulates the absorption of nutrients and prevents the penetration of pathogenic microbes and toxins. Disruptions to this barrier (“leaky gut”) are associated with a variety of diseases, including inflammatory bowel diseases, metabolic disorders and neurological diseases.
Probiotics and barrier function
Probiotics are defined as live microorganisms that provide health benefits when administered in sufficient quantities. The most commonly studied include Lactobacillus, Bifidobacterium and Enterococcus strains and Saccharomyces boulardii. Their effect on the intestinal barrier can be attributed to several mechanisms:
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Strengthening the mucous layer
Probiotics promote the expression of mucin genes (e.g. MUC2) and thus increase the production of the mucus layer, which represents a physical barrier against microbes.
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Modulation of the tight junctions
They regulate the expression and distribution of tight junction proteins (claudins, occludin, ZO-1) and thus stabilize epithelial integrity. This leads to a reduction in intestinal permeability.
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Antimicrobial activity
Many strains produce bacteriocins, lactic acid or hydrogen peroxide, which inhibit the growth of pathogenic germs. They can also suppress biofilm formation and compete directly with pathogens for attachment sites on the intestinal wall.
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Metabolite production
Probiotics promote the formation of short-chain fatty acids (SCFAs) through microbial fermentation of dietary fiber. SCFAs serve as an energy source for epithelial cells, have an anti-inflammatory effect and stabilize tight junctions.
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Immunomodulation
Probiotics influence innate and adaptive immune responses. They induce regulatory T cells, modulate the production of cytokines (e.g. IL-10, TGF-β) and inhibit pro-inflammatory signaling pathways (e.g. NF-κB). They thus contribute to immune tolerance to commensal bacteria and limit excessive inflammation.
Sick pay
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Inflammatory Bowel Disease (IBD): Probiotics improve clinical parameters and reduce mucosal damage in animal models and partially in humans.
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Irritable Bowel Syndrome (IBS): Improvements in symptoms have been reported, although the effects are highly strain-dependent.
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Metabolic diseases: Positive effects on insulin resistance, lipid metabolism and weight control have been described.
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Infection prophylaxis: Probiotics can reduce diarrhea, Clostridioides difficile infections and antibiotic-associated disorders.
Limitations
The effects are strain-specific and cannot be transferred to all probiotics. Differences in dosage, duration of use and population make it difficult to compare studies. In addition, there is often a lack of large-scale, standardized clinical studies.
Conclusion
Probiotics act on the intestinal barrier via various mechanisms and can improve its integrity. This makes them a promising option in the prevention and treatment of barrier-associated diseases. However, further well-designed studies that clarify strain-specific effects, dosages and safety aspects are required for broad clinical application.