Postbiotics are increasingly being discussed alongside probiotics and prebiotics, but what exactly are they, and do they offer anything different? As research into the gut microbiome evolves, postbiotics are gaining attention for their stability and potential clinical applications. Read on to explore what postbiotics are, how they are produced, how they compare to other microbiome interventions, what mechanisms may underpin their effects, and what the current evidence actually shows for postbiotics and gut health.
Postbiotics are the beneficial substances produced by friendly bacteria in your gut, or the inactive bacteria themselves, that can still support your health even once those microbes are no longer alive. Scientists now define postbiotics as preparations of "inanimate microorganisms and/or their components" that have been shown to deliver a health benefit to the person taking them.1
To make postbiotics, specific strains of bacteria (for example, Lactobacillus or Bifidobacterium) are grown in a controlled fermentation process, where they feed on fibres and other nutrients.2 As they grow, they produce a range of bioactive compounds, alongside their own cells. The microbes are then deliberately inactivated, often using heat or pressure, leaving a stable preparation that can contain whole inactivated cells, cell fragments, and the surrounding fermentation broth.
Within these preparations, you might find short-chain fatty acids (like butyrate), complex sugars called exopolysaccharides, vitamins, antimicrobial peptides, and tiny cell wall fragments.3 Together, these postbiotic components help support the gut lining, communicate with the immune system, and form an important part of the wider "gut health toolkit" alongside prebiotics and probiotics.
Probiotics, prebiotics, and postbiotics all support gut health, but they show up in everyday life in different ways. Probiotics are live "good" bacteria found in foods like yoghurt, kefir, sauerkraut, and kimchi, as well as in targeted probiotic supplements.4 Prebiotics are the fibres that feed these friendly microbes, naturally present in foods such as onions, garlic, leeks, asparagus, oats, and slightly green bananas, plus dedicated prebiotic fibre supplements.5
Postbiotics sit at the end of this chain. They are non-living microbial preparations and the beneficial substances made by bacteria during fermentation, such as short-chain fatty acids and tiny cell wall fragments. You'll see them emerging in next-generation gut health products, where they can be combined with prebiotic fibres and live cultures. Because postbiotics aren't alive, they can be more stable in drinks, powders and functional foods, although research is still catching up compared with traditional probiotics and prebiotics.
Postbiotics deliver ready-made microbial signals and metabolites that "talk to" the gut and immune system, rather than adding more live bacteria. Many effects are driven by short-chain fatty acids, peptides, and cell-wall components produced during fermentation.
The benefits of postbiotics may include support of digestive comfort, immune balance, and gut barrier integrity, with early research also exploring roles in metabolic, skin, and mental health.
Several studies suggest that postbiotic compounds, especially short-chain fatty acids, help nourish colon cells, support regular bowel movements, and maintain a balanced gut microbiome.10,11 Early clinical work links postbiotics with improvements in symptoms like diarrhoea, bloating, and discomfort in people with irritable bowel syndrome (IBS) and inflammatory bowel disease, though it should be noted that larger, longer-term trials are still needed.12,13
Because much of the immune system sits in and around the gut, postbiotics that strengthen the gut barrier and influence immune signalling may help the body respond more appropriately to everyday challenges. Emerging human data suggest that certain postbiotic preparations can reduce the frequency or severity of common infections and may help calm overactive responses in conditions like seasonal allergies and eczema.14,15
Postbiotics appear to support the gut lining by boosting the production of protective mucus, fuelling intestinal cells and helping to tighten the "junctions" between them. In lab and animal studies, this is associated with lower gut inflammation and less tissue damage, which may have knock-on effects for whole-body inflammatory balance.11,16
Researchers are now exploring postbiotics in areas such as metabolic health, cardiovascular risk, mood and stress, and even topical skincare, where microbial components may support skin barrier function.17 Food technologists are also using postbiotics in next-generation functional foods, supplements, and even "active" packaging, thanks to their stability and antimicrobial properties.18
Human studies on postbiotics are still relatively new, but they are growing fast, especially in gut and immune health. Overall, results are encouraging, yet not strong enough to replace standard medical care or well-established probiotic and prebiotic strategies.
Clinical trials have tested postbiotic preparations in infants, children and adults for outcomes such as diarrhoea, respiratory infections, IBS symptoms and inflammatory bowel disease. Some studies report shorter episodes of acute diarrhoea, fewer antibiotic-associated gut issues and reduced risk of common colds or respiratory infections compared with placebo.19,20
The most consistent signals so far are in digestive complaints and everyday immune support. For example, randomised trials of heat-treated Lactobacillus and Bifidobacterium preparations have reported shorter episodes of acute diarrhoea in children and fewer common respiratory infections compared to placebo.21,22
Many trials are small, short, and use different strains, doses, and formulations, which makes it hard to compare results or define "best" postbiotics for specific conditions. Researchers are calling for larger, longer, well-controlled studies with standardised definitions, better characterisation of postbiotic preparations, and clearer regulatory guidance.
For healthcare professionals, postbiotic supplements are best positioned as a potential add-on within a broader microbiome-supportive plan, rather than as a standalone or first-line therapy. The focus should remain on foundations like diverse plant intake, adequate fibre, sleep, movement, and stress management, with postbiotics considered where stability, safety and ease of use offer an advantage (for example, in older adults, infants, or patients, where live probiotics are less suitable).
When discussing probiotics, it can be helpful to frame them as one more tool that might complement prebiotics and probiotics, not replace them. Evidence is most developed for digestive and everyday immune outcomes, and is still emerging in areas like skin and metabolic health. As with fibre progression, any introduction should be individualised, monitored over time, and anchored in shared decision-making.
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