Prebiotics vs Probiotics: What's the Difference?

Gut health has become an increasingly popular topic, but with so many products and terms to understand, it can be difficult to know what your digestive system actually needs.

Two terms you may have come across are prebiotics and probiotics. Although they sound similar, they have different roles. Understanding the difference can help you make more informed choices about your diet and the supplements you take.

In simple terms, prebiotics are substances used by certain gut microorganisms, while probiotics are live microorganisms that provide a health benefit when taken in adequate amounts. ¹ ²

Both are studied for their potential role in gut health, but they aren't interchangeable, and the benefits depend on the specific ingredient or microorganism.

1. What are prebiotics?

Prebiotics are substances that are selectively used by microorganisms in the body and provide a health benefit. ¹ Many well-established prebiotics are types of carbohydrate that reach the large intestine, where gut microorganisms can use them. You can think of certain prebiotics as a source of nourishment for microorganisms living in your gut.

Some familiar foods contain fibres and carbohydrates that can act as prebiotics, including:

Onions and garlic: Contain inulin and related compounds.
Leeks and asparagus: Provide naturally occurring prebiotic carbohydrates.
Chicory root: A source of inulin, which is often used in foods and supplements.
Oats: Provide beta-glucan and other fibres that can be used by gut microorganisms.
Beans and lentils: Contain a mixture of fibres and resistant carbohydrates.

Not all dietary fibre is classified as a prebiotic, and not every prebiotic works in the same way. ¹ However, eating a variety of fibre-containing plant foods is a practical way to support a balanced diet and normal digestion.

2. What are probiotics?

Probiotics are live microorganisms that, when taken in adequate amounts, provide a health benefit. ² They are often discussed in relation to gut health because some have been studied for their effects on digestion and particular gastrointestinal conditions.

Probiotics are not all the same. Different strains can have different properties, and evidence for one strain cannot automatically be applied to another.

Some fermented foods contain live microorganisms, including certain yoghurts and kefir. However, not every fermented food is a probiotic food. Whether a food qualifies depends on the microorganisms present and the evidence supporting a health benefit. ³

Probiotic microorganisms may also be included in specific supplements, but the type of microorganism, amount, quality and evidence behind the product all matter.

3. Prebiotics vs probiotics: what's the difference?

The easiest way to understand the distinction is to look at their different roles.

Feature	Prebiotics	Probiotics
What are they?	Substances used selectively by microorganisms, with a health benefit	Live microorganisms that provide a health benefit when taken in adequate amounts
Main role	Provide a resource that certain microorganisms can use	Introduce specific live microorganisms
Where can you find them?	Certain fibres and carbohydrates in foods such as onions, garlic, pulses and chicory root	Certain fermented foods and specific supplements
Are they the same as fibre?	No, although some prebiotics are types of fibre	No, probiotics are live microorganisms
Do all products work the same way?	No, effects depend on the specific substance	No, effects depend on the strain and product

Both are relevant to research into gut health, but neither is a guaranteed solution for digestive symptoms. ¹ ²

4. How do prebiotics and probiotics relate to gut health?

Your digestive system contains a complex community of microorganisms, often called the gut microbiota. These microorganisms interact with one another and with your body in different ways. Diet is one factor that can influence this community. Certain prebiotics can be used by gut microorganisms, while particular probiotic strains have been studied for specific health effects. ¹ ²

However, gut health is broader than simply having more of one type of bacteria. It also involves normal digestive function, symptoms, diet and overall health. ⁴

This is why it's worth being cautious about products that promise to completely balance your gut or transform your digestive health. Research is ongoing, and the effects of a food or supplement can vary depending on its ingredients and the individual taking it. For everyday wellbeing, a varied diet that includes a range of plant foods is a sensible starting point.

5. Can you get prebiotics and probiotics from food?

Yes, although the sources are different.

To include more prebiotic-containing foods, try adding:

Oats to breakfast
Onions, garlic or leeks to soups and sauces
Beans and lentils to curries and salads
Asparagus and other vegetables to main meals
A variety of fruit, vegetables, pulses, nuts and seeds

These foods can also help increase your fibre intake, which is important for digestive health.

To include foods containing live microorganisms, you could consider certain yoghurts labelled as containing live cultures or kefir. Check product labels, as processing and storage can affect whether live microorganisms remain in the finished food. Fermented foods vary, and fermentation alone doesn't establish that a product provides a specific probiotic health benefit. ³

You don't need to eat every food on these lists. Choose options you enjoy and introduce new foods gradually, especially if you're not used to eating much fibre.

6. Should you take prebiotic or probiotic supplements?

Supplements can be useful in certain circumstances, but they aren't essential for everyone.

Prebiotic supplements provide specific ingredients that can be used by gut microorganisms. Probiotic supplements contain selected live microorganisms. The evidence and potential benefits depend on the particular product, ingredient or strain and the reason for taking it. ¹ ²

Before choosing a supplement, consider:

Your diet: Are you eating a variety of fibre-rich foods?
Your reason for taking it: Are you looking to increase fibre intake, or have you been advised to consider a particular product for a specific concern?
The ingredients: Does the label clearly identify what the product contains?
The evidence: Is there research relevant to the specific ingredient or strain and the intended use?
Your individual circumstances: If you have a digestive condition, take medication or have a weakened immune system, seek advice from a healthcare professional before using a probiotic supplement.

If you're considering a fibre supplement such as psyllium husk, follow the product instructions and drink sufficient fluids. Increase fibre gradually to help minimise gas or bloating.

Remember that supplements should complement a balanced diet rather than replace it.

7. What about bloating and digestive discomfort?

Bloating, wind and changes in bowel habits can have many causes, including dietary changes, constipation, food intolerances and digestive conditions.

Increasing fibre can help some people, particularly if their usual intake is low, but suddenly eating much more fibre or taking certain prebiotic ingredients can also increase gas and bloating.

If you're making changes to your diet, start gradually and pay attention to how your body responds. Probiotic products are sometimes marketed for digestive discomfort, but benefits are not guaranteed and evidence varies depending on the strain and condition being studied. ²

If bloating is persistent, keeps returning or is accompanied by symptoms such as unexplained weight loss, blood in your stools or significant abdominal pain, seek medical advice rather than relying on supplements.

FAQs

Can you take prebiotics and probiotics together?

Yes, some products combine both and are known as synbiotics. These contain live microorganisms and ingredients intended to be used by microorganisms, with the combination designed to provide a health benefit. ⁵ However, combining them doesn't automatically make a product more effective.

Are prebiotics better than probiotics?

Neither is universally better. They have different roles, and the most appropriate choice depends on your diet, individual needs and the evidence for the specific ingredient or microorganism.

Is yoghurt a prebiotic or a probiotic?

Some yoghurts contain live microorganisms and may qualify as probiotic foods when the relevant requirements are met. Yoghurt is not automatically a probiotic, and it isn't generally classified as a prebiotic simply because it contains live cultures. ³

Are bananas prebiotic?

Bananas contain fibre and carbohydrates, including resistant starch in greener bananas. These can be used by gut microorganisms. However, not every food that contains fibre is necessarily classified as a prebiotic under the scientific definition. ¹

Do I need a supplement for gut health?

Not necessarily. Many people can support their digestive health through a varied diet containing wholegrains, fruit, vegetables, pulses, nuts and seeds. Supplements may be useful in particular circumstances, but they aren't a requirement for everyone.

Prebiotics and probiotics are related, but they aren't the same. Prebiotics are substances used by certain microorganisms, while probiotics are live microorganisms that provide a health benefit when taken in adequate amounts.

Both are important areas of gut health research, but the effects depend on the specific ingredient or strain rather than the label alone.

For everyday digestive wellbeing, start with a varied, balanced diet and plenty of fibre-containing foods. If you're considering a supplement, look at the ingredients and evidence, and seek professional advice if you have ongoing symptoms or a health condition.