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Prebiotics, Probiotics and Postbiotics - what's the difference?

Gut Health 101

New day, new buzzword. Nutritional Therapist, Grace Carey-Caton breaks down the difference between these trending topics in gut health.

Let’s start with a basic summary definition before we go into more detail:

Probiotics: beneficial bacteria

Prebiotics: food for these bacteria

Postbiotics: beneficial by-products of pro and prebiotics.

What are probiotics?

Probiotics are classified and defined as live microorganisms that when consumed  in adequate amounts offer a health benefit. Probiotics can be taken in supplement form and have a role to support our immune system, gut health and mental health.

There are many different probiotic varieties known as strains, the most common belonging to groups called Lactobacillus and Bifidobacterium. Each different type of probiotic is researched and may have a different effect and health benefit on the body.

Our article What is a Probiotic? offers a more in-depth look at the definition.

What are prebiotics?

Prebiotics are plant fibres that stimulate the growth of bacteria (probiotics) in the gut. Essentially, they feed our microbes and help them to thrive. Prebiotics can be found in foods such as bananas, asparagus, artichokes, apples, onions and garlic.

They move through the small intestine undigested and ferment when they reach the large colon. This fermentation process feeds beneficial bacteria colonies and helps to increase the number of desirable bacteria in our digestive system. In addition to promoting the growth of beneficial bacteria, prebiotics may also help food move more efficiently through the gut.

What are postbiotics?

When probiotics that live in the colon are fed using prebiotics, the probiotic bacteria will generate a secondary beneficial effect during the fermentation process -this is what we mean by postbiotics.

In essence, prebiotics + probiotics = postbiotics. 

Unlike pre and probiotics, postbiotics aren’t something that can be taken as a supplement nor are they found in food, they describe the process and the benefits of combining pro and prebiotics.

There are many different kinds of postbiotics, which include short chain fatty acids, proteins and metabolites. Each compound has a different function and benefit on the body. This includes regulation of digestion, nutrient absorption, detoxification, regulation of the immune system and gut-brain-axis communication.


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Grace Carey-Caton, Nutritional Therapist

Grace Carey-Caton is a Registered & Licensed Nutritionist (mBANT) (rCNHC). Her clinic is London based and she specialises in Gut Health and Female Health.