Prebiotics and probiotics may sound almost identical, but they're not the same thing.
Put simply, probiotics are specific live microorganisms that can provide a health benefit when consumed in adequate amounts, while prebiotics are substrates that are selectively used by microorganisms and provide a health benefit.
You can find both through food, while probiotic and prebiotic supplements are also available.
So, do you need one, the other or both? Let's take a closer look at prebiotics vs probiotics, what they do and where you can find them.
What Are Probiotics?
Probiotics are defined as live microorganisms that, when administered in adequate amounts, confer a health benefit on the host.
You'll often hear them referred to more generally as "friendly" or "good" bacteria, although not all probiotics are bacteria.
Your digestive tract naturally contains an enormous community of microorganisms. This community forms part of what we call the gut microbiome.
Probiotics are particular microorganisms that have been studied for specific characteristics or uses. That's an important distinction because not every microorganism found in a fermented food or supplement can automatically be called a probiotic.
What Are Probiotic Strains?
One of the most important things to understand about probiotics is that they're not all the same.
You may see names such as Lactobacillus and Bifidobacterium on supplement labels, but probiotic identification goes further than simply looking at the type of bacteria.
Different species – and particularly different strains – can have different characteristics.
This means evidence relating to one probiotic strain shouldn't automatically be applied to another.
When comparing probiotic supplements, consider the specific microorganisms and strains included rather than simply choosing the product with the longest ingredient list or largest number on the front of the pack.
Our guide to probiotics and probiotic strains explores this in more detail.
What Foods Contain Probiotics?
Fermented foods are often discussed alongside probiotics.
Examples include:
- Live yoghurt
- Kefir
- Sauerkraut
- Kimchi
- Miso
- Tempeh
- Some kombuchas
However, fermented and probiotic don't mean exactly the same thing.
Some fermented foods contain live microorganisms when eaten, while others don't. Processing methods such as heat treatment can remove or deactivate live microorganisms.
And even when a food contains live microorganisms, that doesn't automatically mean those microorganisms meet the scientific definition of a probiotic.
Fermented foods can nevertheless be a useful way of introducing greater variety into your diet.
What Are Prebiotics?
Prebiotics are different from probiotics.
A prebiotic is a substrate that is selectively utilised by host microorganisms and confers a health benefit.
Certain types of dietary fibre can have prebiotic properties.
Unlike probiotics, you're not consuming live microorganisms. Instead, prebiotic substances reach microorganisms already living within the body, where they can be selectively utilised.
This is why you'll sometimes hear prebiotics described more simply as "food for your gut bacteria".
That's a useful way to picture the basic difference, although the scientific definition of a prebiotic is more specific than simply being something that bacteria can consume.
What Foods Are Naturally High in Prebiotics?
You can obtain prebiotic fibres through everyday foods.
Sources include:
- Onions
- Garlic
- Leeks
- Chicory root
- Jerusalem artichokes
- Asparagus
- Bananas
- Oats
Some nuts, seeds, pulses, whole grains, fruit and vegetables also provide different types of fermentable dietary fibre.
Rather than concentrating on one particular "prebiotic superfood", eating a varied, plant-rich diet provides your digestive system with many different fibres and plant compounds.
Our guide to eating your way to a healthy gut has more ideas for increasing plant variety, fibre and fermented foods in your everyday diet.
What Prebiotics Are Used in Supplements?
You'll often come across ingredients such as inulin and fructooligosaccharides (FOS) in prebiotic and digestive-health products.
Inulin
Inulin is a type of fructan found naturally in various plants, including chicory root, onions and garlic.
Chicory inulin can also be added to foods or used in supplements.
Fructooligosaccharides (FOS)
FOS are short-chain carbohydrates found naturally in some plants and can also be included in prebiotic supplements.
Other Fibres
As research into the microbiome develops, you'll increasingly see different fibres and compounds discussed in relation to prebiotic activity.
However, it's important not to assume that every dietary fibre is automatically a prebiotic. Prebiotic status depends on evidence demonstrating selective utilisation by microorganisms alongside an associated health benefit.
Prebiotics vs Probiotics: The Key Differences
The easiest way to understand them is side by side.
| Probiotics | Prebiotics | |
|---|---|---|
| What are they? | Specific live microorganisms | Substrates selectively used by microorganisms |
| Are they alive? | Yes | No |
| Where can you find them? | Certain foods and supplements | Certain plant foods, fibres and supplements |
| Examples | Specific probiotic bacterial or yeast strains | Inulin and FOS |
| Main consideration | The specific strain matters | The specific prebiotic substrate matters |
Rather than thinking of prebiotics and probiotics as competing options, it's better to understand that they're fundamentally different things.
What Is a Synbiotic?
You may also come across the term synbiotic.
A synbiotic is a mixture comprising live microorganisms and substrate(s) selectively utilised by host microorganisms that confers a health benefit on the host.
In practical terms, synbiotic products combine microorganisms with appropriate substrates in the same formulation.
However, simply putting any probiotic and any fibre together doesn't necessarily mean the combination meets the scientific definition of a synbiotic.
As with probiotics and prebiotics individually, the particular ingredients and evidence behind the product matter.
Do I Need Both Prebiotics and Probiotics?
Not necessarily.
A varied diet containing plenty of vegetables, fruit, whole grains, beans, pulses, nuts and seeds is a sensible starting point for supporting digestive health and increasing your intake of different types of fibre.
Fermented foods can provide additional dietary variety.
Some people may also choose to use a prebiotic or probiotic supplement depending on their individual circumstances.
The important point is that more isn't automatically better. Taking a probiotic with more strains or a larger CFU count doesn't necessarily make it more appropriate, and dramatically increasing prebiotic fibre isn't always comfortable either.
How Do I Choose a Probiotic Supplement?
The probiotic aisle can be confusing, particularly when products contain different strains and CFU numbers.
When choosing a product, consider:
The Strain
Look beyond terms such as Lactobacillus or Bifidobacterium. Where possible, check which specific strain or strains are included.
Different strains have been researched individually, so evidence for one shouldn't automatically be applied to another.
CFU Count
CFU stands for colony-forming units and is commonly used to describe the quantity of viable microorganisms in a probiotic product.
A larger CFU number doesn't automatically mean a better probiotic.
Rather than looking for an arbitrary number of billions, consider the particular strain, the amount used in relevant research and the manufacturer's recommended serving.
Storage
Some probiotics require refrigeration, while others are formulated to remain stable at room temperature.
Always check the storage instructions on the individual product.
Your Individual Needs
There isn't one probiotic that's right for everybody.
If you're unsure which product is suitable for you, ask an Evergreen team member, pharmacist or other appropriately qualified healthcare professional for advice.
Explore our range of probiotic supplements or read our complete guide to probiotics to learn more.
How Do I Choose a Prebiotic?
Food is a great place to begin.
Eating a varied range of fibre-rich plant foods can provide different fibres alongside vitamins, minerals and other plant compounds.
If you're considering a supplement, check which prebiotic ingredient it contains and how much is provided.
It's also sensible to introduce additional fibre gradually. A sudden increase in fermentable fibre can cause temporary digestive discomfort, including gas and bloating, in some people.
Remember to drink sufficient fluids when increasing your overall fibre intake.
Explore our dietary fibre range or read our guide to fibre and gut health for more information.
Prebiotics, Probiotics and Your Gut Microbiome
The relationship between food, microorganisms and digestive health is much more complicated than simply having "good" and "bad" bacteria.
Your gut microbiome contains a diverse community of microorganisms, and its composition can be influenced by factors including diet, age, environment and lifestyle.
Rather than trying to create a supposedly "perfect" balance of gut bacteria, focus first on the fundamentals:
- Eat a varied diet.
- Include plenty of plant foods.
- Get sufficient dietary fibre.
- Introduce fibre gradually.
- Stay adequately hydrated.
- Include fermented foods if you enjoy and tolerate them.
- Maintain healthy lifestyle habits.
Supplements can then provide more targeted options where they're appropriate for your individual needs.
Frequently Asked Questions
Which Is Better: Prebiotics or Probiotics?
Neither is inherently better because they are different things. Probiotics are specific live microorganisms, while prebiotics are substrates selectively used by microorganisms. Which is relevant depends on your individual circumstances and what you're looking for.
Can You Take Prebiotics and Probiotics Together?
Prebiotics and probiotics can be consumed as part of the same diet or supplement routine. Products specifically combining appropriate live microorganisms and substrates may be described as synbiotics when they meet the relevant scientific definition.
Are Prebiotics Fibre?
Certain dietary fibres meet the definition of a prebiotic, but not every type of fibre is a prebiotic.
Are All Fermented Foods Probiotic?
No. Fermented foods aren't automatically probiotic foods. To be considered probiotic, the specific live microorganisms need to meet the established definition of a probiotic.
What Does CFU Mean in Probiotics?
CFU means colony-forming units and is a measure commonly used to indicate the number of viable microorganisms within a probiotic product.
A higher CFU count doesn't necessarily mean a better product. The strain and amount relevant to that particular microorganism are also important considerations.
Should I Get Prebiotics From Food or Supplements?
A varied diet containing fibre-rich plant foods is a sensible starting point. Prebiotic supplements provide particular prebiotic ingredients in measured amounts and may offer a convenient option for some people.
Supporting Your Gut Through Diet
You don't need to choose a side in the prebiotics vs probiotics debate.
They're different components of the wider gut-health picture.
Start with the foundations: a varied diet containing plenty of plant foods, different sources of fibre and, if you enjoy them, fermented foods. Probiotic or prebiotic supplements can then provide more targeted options where appropriate.
To continue exploring digestive health, read our guides to Eat Your Way to a Healthy Gut, Fibre and Gut Health and Best Supplements for Digestive Health, or explore Evergreen's range of probiotic supplements.
This article is for informational purposes only and should not replace medical advice. Speak to your doctor, pharmacist or another appropriately qualified healthcare professional before taking a new supplement if you have a medical condition, take medication, are pregnant or breastfeeding.
Author: Katy Grieshaber, BSc (Hons) Food, Nutrition and Health, Master's in Public Health
Updated: 18th August 2026
