What's all the fuss with Biotics?

Written by Clare Carrick ANutr BHSc (Nutrition and Health Promotion)

Scientifically reviewed by Dr Fathalla Ali, PHD Paediatrics


‘With the goodness of probiotics’…. ‘Gut-Friendly Prebiotics’….You don’t have to look hard to find some version of a ‘biotic’ stamped on the products lining our supermarket shelves these days…Whether that be prebiotics, probiotics, synbiotics, or the lesser known postbiotics, they seem to be everywhere, and they come with some pretty hefty health claims to boot!


It can all get kind of confusing though… What are they all for, and what do they supposedly do for us? Should we all be taking them? Can we get them in food, or does it have to be in a supplement form? 


This article is designed to break down each of these ‘biotics’ so that you can learn what they are, where you can find them, and what they might be able to do for you!


Prebiotics – Food to Nourish Our Gut Bugs

You can think of prebiotics as the food you eat to feed your gut bugs. Humans are incapable of digesting prebiotics, and so this job gets passed on to our microbes, who are raving fans of all things prebiotic (1). A prebiotic has been described as “a selectively fermented ingredient that results in specific changes in the composition and/or activity of the gastrointestinal microbiota, thus conferring benefit(s) upon host health” (2). One thing all accepted definitions of prebiotics have in common is their association with boosting human well-being (1).


Prebiotics are found naturally-occurring in many carbohydrate foods, including garlic, banana, Jerusalem artichoke, tomato and asparagus (and many more!) (1). In general, however, prebiotic foods only have a low concentration of prebiotic fibre in them (1). This fact, coupled with the fact that hardly anyone eats enough plant foods anyway, has prodded many companies to manufacture synthetic prebiotics, in supplement form, or as an addition to packaged foods (1).


Numerous studies have been conducted on prebiotics, and they are deemed to be a safe and effective way to improve a number of aspects of human health (1). Prebiotics have the ability to strengthen and nurture your gut microbiome, prompting all the flow-on health benefits that we know a healthy gut can provide (1).


Probiotics – Introduce Some New Friends to Your Microbial Community

The formal definition of probiotics is “live microorganisms which, when administered in adequate amounts, confer a health benefit on the host” (3). When you consume probiotics, you are essentially consuming additional microbes to add to your community of existing gut microbes! 


Probiotics have been shown to prevent and help improve a variety of health conditions, including antibiotic-associated diarrhoea, allergic disorders such as eczema and allergic rhinitis in infants, and some inflammatory bowel diseases in adults (4). There’s also plenty of interest in their ability to help with metabolic conditions, like type 2 diabetes, obesity, and non-alcoholic fatty liver disease (4). 


Probiotics can be found in some foods like kimchi, yoghurt, sauerkraut, kefir, and kombucha, but are also readily available in supplement form (4). Whereas prebiotics nurture your existing gut bugs, probiotics can increase the diversity of your gut microbiome, by adding in new strains and restoring balance to a dysbiotic gut (4). 


Synbiotics – A Delightful Combo

The best of both worlds, synbiotics combine probiotics and prebiotics (5). An accepted definition of synbiotics is “a mixture comprising live microorganisms and substrate(s) selectively utilized by host microorganisms that confers a health benefit on the host” (5). There’s still a lot to be learnt about synbiotics, but there are hints that adding prebiotics to probiotics actually has a synergistic effect…i.e. Their combined effect is greater than the sum of their individual effects (6). This is probably because the prebiotic helps the probiotic survive and thrive!


Synbiotic foods include things like sauerkraut or kimchi. Cabbage, onion and garlic are all good sources of prebiotics, and the fermenting process produces probiotic substances, like lactobacillus. Synbiotic supplements and food fortification are also becoming more common.


Postbiotics – One Man’s Trash is Another Man’s Treasure!

OK, that should actually be ‘One Microbe’s Trash is This Man’s Treasure’, but it doesn’t have quite the same ring to it! Postbiotics are probably the least discussed version of all the ‘biotics’ but they are definitely one to watch! Being the newest kids on the block, the formal definition of postbiotics has not been settled on, but one of the more popular definitions is that “postbiotics are bioactive compounds produced by food-grade micro-organisms during a fermentation process. Postbiotics include microbial cells, cell constituents and metabolites” (7). In other words, postbiotics are the products produced (or spat out!) by our microbes after they’re done fermenting all the goodies! You could kind of think of postbiotics as the ‘waste’ products of our ‘probiotic’ gut bugs after they break down the ‘prebiotic’ fibres…except that they are not ‘wasted’ at all! In fact, postbiotics may offer a whole host of various health benefits to us!


You can increase the amount of postbiotics you have by increasing your prebiotic and probiotic (or synbiotic!) consumption, otherwise, there are a few postbiotic supplements available in some stores…definitely not as many as the more popular pre- and probiotics!


Postbiotics have been shown to have potential benefits for the immune system, inflammatory bowel disease, weight loss, and allergies, although more research needs to be done (8). There is also exciting research examining the use of postbiotics in the first few months of an infant’s life, to help support the healthy development of the gut microbiome in this critical time frame (8).


Nurture the Gut

As complicated and confusing as these ‘biotic’ terms might get, the key takeaway is that it all comes back to nurturing the gut! We know that our gut health is central to so many aspects of our overall health, and pre-, pro-, syn- and postbiotics all offer their own unique manipulation technique on our guts. 


  1. Davani-Davari D, Negahdaripour M, Karimzadeh I, Seifan M, Mohkam M, Masoumi SJ, Berenjian A, Ghasemi Y. Prebiotics: definition, types, sources, mechanisms, and clinical applications. Foods. 2019 Mar 9;8(3):92.
  2. Gibson GR, Scott KP, Rastall RA, Tuohy KM, Hotchkiss A, Dubert-Ferrandon A, Gareau M, Murphy EF, Saulnier D, Loh G, Macfarlane S. Dietary prebiotics: current status and new definition. Food Sci Technol Bull Funct Foods. 2010 May 7;7(1):1-9. 
  3. Hill C, Guarner F, Reid G, Gibson GR, Merenstein DJ, Pot B, Morelli L, Canani RB, Flint HJ, Salminen S, Calder PC. Expert consensus document: The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic. Nature reviews Gastroenterology & hepatology. 2014.
  4. Plaza-Diaz J, Ruiz-Ojeda FJ, Gil-Campos M, Gil A. Mechanisms of action of probiotics. Advances in nutrition. 2019 Jan 1;10(suppl_1):S49-66. 
  5. Swanson KS, Gibson GR, Hutkins R, Reimer RA, Reid G, Verbeke K, Scott KP, Holscher HD, Azad MB, Delzenne NM, Sanders ME. The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of synbiotics. Nature Reviews Gastroenterology & Hepatology. 2020 Nov;17(11):687-701.
  6. Markowiak P, Śliżewska K. Effects of probiotics, prebiotics, and synbiotics on human health. Nutrients. 2017 Sep 15;9(9):1021.
  7. Wegh CA, Geerlings SY, Knol J, Roeselers G, Belzer C. Postbiotics and their potential applications in early life nutrition and beyond. International journal of molecular sciences. 2019 Sep 20;20(19):4673.
  8. Żółkiewicz J, Marzec A, Ruszczyński M, Feleszko W. Postbiotics—a step beyond pre-and probiotics. Nutrients. 2020 Aug;12(8):2189.

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