What is the difference between prebiotics, probiotics and postbiotics?

From live yoghurts to health supplements, these terms are used to describe the active ingredients that claim to be able to transform the health of the microbiome. 
3 min read
Dr Joe Inglis BVSc MRCVS
Head of Veterinary Sciences

From live yoghurts to health supplements, the terms prebiotic, probiotic and, more recently, post-biotic, are used to describe the active ingredients that claim to be able to transform the health of the microbiome. But what exactly do these terms mean, and what are the differences between them? 


The term probiotics refers to beneficial live bacteria that usually live in the intestinal tract and can be added to foods or supplements to boost these populations. Consuming so-called ‘good bacteria’ in this way is thought to help maintain a healthy balance and diversity of species, and prevent ‘bad’ bacteria from taking over and causing health problems. Probiotics can also help to strengthen the gut wall against illness and infections, and support normal bowel movements, as well as helping to maintain overall health beyond the intestinal tract.

Probiotics are usually given as supplements, or as additives in complete foods, as this allows precise dosing with specific species of bacteria known to be beneficial. However, probiotic species can also come directly from the diet by including foods such as live yoghurt, raw and fermented vegetables.


Prebiotics are foods such as inulin, chicory and artichoke extract that nourish the bacteria in your dog's gut microbiome, and are usually high in fibre that is hard for dogs to digest directly and can only be broken down by intestinal bacteria. Once the fibre reaches the colon, where most of the ‘good’ bacteria live, they are digested into short chain fatty acids which have many essential roles in the rest of your dog’s body. 

Prebiotic fibre has been found to help reduce gastrointestinal symptoms such as bloating, gas and pain, and has been associated with reduced risk of various chronic diseases, such as heart disease, cancer and diabetes. 

Concentrated fibre-rich supplements are the best way to boost your dog’s intake of prebiotics, as even the most fibrous foods tend not to have sufficient prebiotic content to make a significant difference to a dog’s dietary intake.


In recent years a new category of dietary supplements have been developed called postbiotics, and these are effectively the active compounds that the good gut bacteria produce after eating their diet of prebiotic fibre. This is a complex mixture of bioactive compounds, including fatty acids, cell wall fragments, enzymes, amino acids, vitamins and other waste compounds produced by bacteria and yeasts. It is thought that a lot of the beneficial effects demonstrated by pre and probiotics, might actually be the effects of postbiotics. 

So, what exactly can postbiotics do? Some postbiotic compounds such as short chain fatty acids, like butyrate, have been found to help with certain digestive ailments, such as IBD (Inflammatory Bowel Disease) or ulcerative colitis, and butyrate can also help stimulate the production of T cells (an important immune cell), and so boost your dog's immune response[2]. Other postbiotics, like cell wall fragments and supernatant, can increase cytokine production, helping to reduce inflammation and support certain immune responses. In humans, postbiotics have even been found to protect against infections, such as colds, as well as preventing and treating diarrhoea. Other potential effects of these substances are still being investigated, but might include helping with allergies, weight loss, managing blood sugar levels and lowering the risk of heart disease. Watch this space. 

The easiest way to increase the level of postbiotics in your dog’s system, is to support the populations of good bacteria by supplementing with pre and probiotics, but it is also possible nowadays to directly supplement with postbiotics.

All 3 of these ‘biotics’ are essential for maintaining a healthy microbiome, and when it comes down to it, it is very difficult to know which one of the three the beneficial effects may stem from - but what we do know is that the addition of pre, pro, and postbiotics, or all 3, is going to significantly improve gastrointestinal health, as well as helping to improve or prevent a wide range of other health issues.


[1] Honneffer JB, Minamoto Y, Suchodolski JS. Microbiota alterations in acute and chronic gastrointestinal inflammation of cats and dogs. World J Gastroenterol. 2014 Nov 28;20(44):16489-97. doi: 10.3748/wjg.v20.i44.16489. PMID: 25469017; PMCID: PMC4248192.

[2] Silva JPB, Navegantes-Lima KC, Oliveira ALB, Rodrigues DVS, Gaspar SLF, Monteiro VVS, Moura DP, Monteiro MC. Protective Mechanisms of Butyrate on Inflammatory Bowel Disease. Curr Pharm Des. 2018;24(35):4154-4166. doi: 10.2174/1381612824666181001153605. PMID: 30277149.

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Frequently asked questions

  • The microbiome is the name given to the collection of microbes, mostly bacteria, but also fungi and protozoa, that exist within your dog’s gut. It is a diverse and complex microbial community which can directly affect health and wellbeing. We know that 90% of a human’s body cells are microbes, with only 10% being human cells – it’s just that human cells are markedly larger than the microbes. It’s similar for our four-legged friends. Testing the microbiome gives us an idea of exactly which bacteria are present in your dog’s gut and this can help indicate existing or future health problems.

  • A healthy diversity within the microbiome has been found to be an accurate indicator of overall health and wellbeing. If your dog appears healthy, but has an imbalance in their microbiome, then this could be an indicator of a potential future health issue. If your dog has any existing health complaints, then improving the health of their microbiome can help to improve immune system health and overall wellbeing, as well as improving disease symptoms.

  • Testing and treatment have the potential to help with a whole range of different health complaints. The immune system is very closely associated with the gut, so any imbalance in the microbiome can influence immune system health, overall vitality and wellbeing. Our supplement recommendations are also tailored to your individual dog, with specific ranges designed to help with gastrointestinal inflammation, joint problems, allergies and skin complaints, to name a few.

  • All you need to do is order a kit online and fill in our questionnaire about your dog and their general health. We will then send the kit out to you by post. You then just need to collect a sample and return it to us, again by post. Once the test is performed, we will email the results directly to you.

  • You do not need to get your vet’s permission to test, or talk to them about performing the test beforehand. We do recommend that you pass on a copy of your test results to your regular vets, as it may help them in understanding your pet’s current health, and any future complaints they may have.

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