Probiotics or Prebiotics: The Difference

Picture your large intestine as a densely populated garden: trillions of microorganisms live there, and like any garden it needs two things – the plants themselves and the soil that nourishes them. This is exactly where the difference between probiotics and prebiotics lies, a distinction that is so often mixed up. Probiotics are living bacterial cultures; prebiotics are the indigestible dietary fibres these cultures feed on. One letter apart, two completely different things – and an interplay that works with remarkable elegance.

The key points at a glance

• Probiotics = living microorganisms (bacterial cultures such as lactobacilli & bifidobacteria).
• Prebiotics = indigestible dietary fibres (e.g. inulin, oligofructose) that serve these cultures as food.
• Memory aid: probiotics are the cultures, prebiotics are their food.
• The deliberate combination of the two is called a synbiotic.
• No health claims are authorised for probiotics in the EU – we describe them factually and neutrally.

Probiotics: the living cultures

Probiotics are living microorganisms – overwhelmingly bacteria from the large families of lactobacilli and bifidobacteria, and less commonly certain yeasts such as Saccharomyces. You have known them from your kitchen for a long time, even if you may not have been aware of it: the live yoghurt in the morning, the glass of kefir, a forkful of raw sauerkraut, Korean kimchi or a sip of kombucha – these are all fermented foods in which such cultures are active.

What makes these tiny organisms so special? A human being carries roughly as many bacterial cells in and on the body as their own body cells – an enormous ecosystem that sits mainly in the large intestine. This microbiome is involved in the digestion of dietary fibre, forming short-chain fatty acids in the process and even producing certain vitamins such as vitamin K and some B vitamins. Probiotic cultures are, in a sense, fresh newcomers that add to this community. In food supplements they come as a capsule or powder, usually with a stated germ count in CFU (colony-forming units). Because the individual strains differ in their properties, many products deliberately combine several cultures – on the principle that a diverse team is more robust than a lone fighter.

Prebiotics: the food behind the scenes

Prebiotics are the exact opposite of living organisms: they are certain indigestible dietary fibres. What is fascinating about them is what does not happen to them. Unlike sugar or starch, your small intestine cannot break these fibres down at all. So they travel on undigested until they reach the large intestine – and it is right there that they become a feast for the resident bacteria, which break them down in the course of fermentation and gain energy from them.

The best-known examples are inulin and oligofructose, alongside substances such as galacto-oligosaccharides or resistant starch. You don't need to go to the pharmacy for them: chicory, Jerusalem artichoke, onions, garlic, leek, asparagus, slightly under-ripe bananas and rolled oats all supply prebiotics quite naturally. You'll find a more in-depth look in our guide Inulin & prebiotics: effect and use. Psyllium husks also belong to the broad field of dietary fibres that keep digestion busy.

An important practical note for getting started: anyone who has eaten little fibre so far and then suddenly ramps up the amount sharply often feels an increased sense of fullness or bloating at first. This is not a sign of intolerance, but simply fermentation running at full speed before the gut flora has adapted. So increase prebiotic foods slowly and step by step and drink plenty of water alongside – then your digestive system can get used to the larger amount at its own pace.

Probiotics or prebiotics: a direct comparison

The difference is therefore crystal clear: one lives, the other nourishes. No wonder both are almost always mentioned in the same breath – they are a well-matched duo.

Synbiotics: when the two work together

When probiotics and prebiotics are deliberately combined, this is called a synbiotic. The logic behind it is compellingly simple: you supply the fresh cultures and their matching food along with them. Whether as a ready-made combination product or entirely naturally – a yoghurt with a few rolled oats and some banana is essentially already a home-made synbiotic – the principle stays the same: the cultures get exactly what they live on.

What is remarkable about the gut microbiome is its individuality. No two people harbour exactly the same bacterial community – the composition is as unique as a fingerprint and is shaped by diet, exercise, age and lifestyle. That is precisely why a varied, plant-focused diet with many different sources of fibre is regarded as the foundation: a varied menu offers a varied gut flora correspondingly varied food. How the microbiome is structured and why it receives so much attention is something we explore in more depth in Gut, microbiome & probiotics.

What research is investigating

The microbiome is one of the most exciting fields of research of the past two decades. Scientists are intensively investigating how the composition of the gut flora relates to a wide range of bodily functions – from digestion through metabolism to the so-called gut–brain axis, that is, the communication between the gut and the nervous system. Research is also looking at which individual bacterial strains take on which tasks and how stably introduced cultures establish themselves in the gut.

To be honest, much of this is still open, young research. A lot of what is observed in studies is strain-specific – meaning that findings on one particular bacterial strain cannot simply be transferred to others. What is well documented and undisputed, by contrast, is the fundamental role of gut bacteria in the fermentation of dietary fibre and the formation of short-chain fatty acids. We deliberately stick here to what is established, and describe cultures and dietary fibres on the basis of what they are – not on the basis of promised effects.

An honest classification: the legal framework

One point we address openly: no health claims are currently authorised for probiotics in the EU. The term “probiotic” itself is already legally considered a health claim and may only be used on products to a limited extent. This is the reason why you won't read any grand promises about cultures from us – not out of reticence on the matter itself, but because we adhere to this framework. We therefore describe bacterial cultures and prebiotic fibres factually: what they are, where they come from, how they are used. In the case of persistent digestive complaints, the rule is: please have them clarified by a doctor.

What to look out for when buying

If you are interested in cultures or dietary fibres as a supplement, it is worth looking at a few quality features:

• Strain diversity: several combined strains cover a broader spectrum.
• Germ count (CFU): it should be clearly declared and ideally guaranteed until the end of the shelf life, not just at the date of manufacture.
• Fibre source: with prebiotics it is worth checking which fibre (inulin, oligofructose …) and how much it contains.
• Processing & testing: laboratory-tested and with a clean declaration – see Laboratory-tested: what does it mean?

Whether you reach for a capsule or a powder is above all a matter of preference – we compare the two in Probiotics: capsule or powder? You can read about what else matters when choosing a product in How to recognise probiotic quality. Since a balanced diet forms the basis, Nutrients & digestion also fits the picture, and anyone combining several preparations will find guidance in Combining supplements correctly. How well individual substances actually reach the body is clarified in Bioavailability explained simply.

Matching products from Scheunengut

You'll find living bacterial cultures in our Bacterial cultures category, and prebiotic fibres plus everything to do with digestion in Gut & digestion. Anyone wanting an overall overview will find it in All products. All laboratory-tested and made in Germany.

Frequently asked questions (FAQ)

What is the difference between probiotics and prebiotics?

Probiotics are living bacterial cultures (e.g. lactobacilli and bifidobacteria); prebiotics are indigestible dietary fibres such as inulin that serve these cultures as food. In short: probiotics are the cultures, prebiotics are their food. When the two are deliberately combined, this is called a synbiotic.

Can I take probiotics and prebiotics together?

Yes – that is in fact the idea behind a synbiotic: you supply the cultures and their matching food along with them. This works as a combination product or entirely naturally – for example yoghurt with rolled oats and banana. Increase prebiotic fibre slowly, so that your digestion can get used to the larger amount at its own pace.

Which foods contain probiotics and prebiotics?

You'll find probiotic cultures in fermented foods such as live yoghurt, kefir, raw sauerkraut, kimchi and kombucha. Prebiotic fibres are found above all in chicory, Jerusalem artichoke, onions, garlic, leek, asparagus, slightly under-ripe bananas and rolled oats. A varied, plant-focused diet covers both.

Why does a lot of fibre cause bloating at first?

Prebiotic fibres are fermented by bacteria in the large intestine – and this produces gases. If you suddenly increase the amount sharply, this fermentation runs at full speed before the gut flora has adapted. This is harmless and usually settles down when you increase the amount step by step and drink enough.