Prebiotics often stand in the shadow of their more well-known "relatives," probiotics. While probiotics are living microorganisms that we ingest through food or supplements, prebiotics serve as food for the beneficial bacteria in the gut. They are, so to speak, the fuel for a balanced and efficient microbiome. But why exactly does the body need these special dietary fibers?
In this blog post, we explain in detail why prebiotics are so important, how they work in the body, and what influence they have on digestion, well-being, and the immune system.
What exactly are prebiotics?
Prebiotics are indigestible dietary fibers—usually special carbohydrates—that pass through the small intestine unchanged and are fermented by gut bacteria only in the large intestine. The best-known prebiotic substances include:
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Inulin
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Oligofructose (FOS)
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Galactooligosaccharides (GOS)
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Resistant starch
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Certain beta-glucans
It's important to note: prebiotics selectively promote the growth of beneficial bacteria, such as Lactobacillus and Bifidobacterium. This allows them to specifically shape a healthy microbial environment.
Why our body needs prebiotics
1. Prebiotics promote a healthy gut flora
The microbiome is a highly complex ecosystem of billions of microorganisms. A balanced gut flora supports the body in:
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Nutrient absorption
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Digestion
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Inflammation regulation
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The production of important metabolic products
Prebiotics specifically increase the number of "good" bacteria—those that produce certain substances, perform protective functions, and displace potentially harmful germs ("colonization resistance").
2. They form short-chain fatty acids (SCFAs) – small molecules with a big impact
When gut bacteria ferment prebiotics, they produce short-chain fatty acids such as:
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Butyrate
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Propionate
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Acetate
These molecules have impressive effects:
Butyrate
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Main energy source for the cells of the intestinal mucosa
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Supports the regeneration of the intestinal epithelium
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Strengthens the barrier function ("leaky gut" prevention)
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Inhibits inflammatory processes
Propionate and Acetate
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Support metabolism
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Regulate hunger pangs
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Can have a positive influence on blood sugar control
SCFAs thus act far beyond the gut—they are true multi-talents in the body.
3. Prebiotics support the immune system
Around 70% of our immune system resides in the gut. A healthy microbiome trains immune cells, helps the body distinguish between "friend" and "foe," and regulates inflammatory responses.
Prebiotics promote precisely those bacteria that:
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produce anti-inflammatory substances
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modulate the immune system
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displace pathogenic (harmful) microorganisms
This means immune responses are balanced rather than excessively activated.
4. They can regulate digestion
Prebiotics increase stool volume and support healthy bowel movements. Many people therefore experience:
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less constipation
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more regular digestion
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less bloating in the long term (in the short term, they can occur as the flora adapts)
They act like a natural "gut trainer."
5. Prebiotics can influence mental well-being ("gut-brain axis")
Research shows: The microbiome communicates with the brain via nerves, hormones, and metabolic products.
By promoting a healthy microbiome, prebiotics can:
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reduce stress responses
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improve sleep
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support general well-being
Studies show that certain prebiotic fibers can even influence cortisol, the stress hormone.
6. Prebiotics support mineral balance
An exciting effect: prebiotics can improve the absorption of minerals such as calcium, magnesium, and iron. This is because the formation of SCFAs lowers the pH value in the gut, which makes certain nutrients more soluble.
7. How many prebiotics do you need?
Most people consume significantly less fiber than recommended. The general recommendation for fiber is at least 25–30g per day, some grams of which can come from prebiotic fibers.
Good natural sources include:
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Chicory
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Jerusalem artichoke
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Leeks, onions, garlic
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Asparagus
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Legumes
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Oats
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Green vegetables
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Bananas (the riper, the more resistant starch)
Fermented drinks like kombucha are also not automatically prebiotics. Whether a food has prebiotic properties or influences corresponding processes depends on its specific contained components and the respective scientific evidence.
8. Prebiotics and Probiotics – a powerful duo
Probiotics introduce beneficial bacteria into the gut, while prebiotics help them grow and become "established" there. Together, they form a synbiotic, a synergistic combination.
For foods or supplements that combine both, research shows particularly positive effects.
9. What is Kombucha – Prebiotic or Probiotic?
Kombucha is a fermented drink made from tea, sugar, and a community of bacteria and yeasts. Depending on the production method, unpasteurized kombucha can contain living microorganisms as well as organic acids and other fermentation products.
Is kombucha a probiotic? Not automatically. The term probiotic requires defined microorganisms and other specific conditions. The mere presence of living cultures does not universally make kombucha a probiotic.
Is kombucha a prebiotic? This classification also cannot be generally applied to kombucha. Prebiotics are specific, indigestible substances that can be utilized by microorganisms.
Kombucha is therefore best described as a fermented tea drink with a complex mixture of cultures and fermentation products.
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Conclusion: Prebiotics are essential for a healthy microbiome
Prebiotics are much more than simple dietary fibers. They:
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nourish good gut bacteria
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support digestion and the immune system
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promote the production of valuable metabolic substances
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strengthen the gut barrier
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have a positive effect on energy balance and well-being
A sufficiently high intake of prebiotic dietary fibers is one of the simplest and most effective measures to support one's gut in the long term.
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