It can feel as though barely a day goes by without a new revelation about gut health. Probiotics have long dominated the conversation, but as our understanding of the microbiome deepens, so too does our appreciation of how microbes support a healthy gut. The trillions of bacteria living in our digestive system influence far more than digestion alone, playing a pivotal role in immune health, mood and energy regulation.
Yet it’s not only live cultures that matter. Cue dead bacteria, otherwise known as postbiotics which refer to non-living bacteria and their beneficial by-products. Once overlooked, dead bacteria are now a rapidly growing area of research, offering a new way to support health without the need for live cultures—a distinction that, as you’ll soon discover, comes with some surprising advantages.
What is dead bacteria?
Dead bacteria, or postbiotics as they’re commonly known, refer to inactivated microorganisms and the beneficial compounds they produce, including enzymes, peptides, short-chain fatty acids, polysaccharides and bacterial cell fragments. While these microbes may no longer be alive, their components remain biologically active, meaning they can still interact with the body in positive ways.
Unlike probiotics, postbiotics don’t need to survive stomach acid or colonise the gut to be effective. This makes them a more stable and predictable option for many people, including older adults, those with compromised immune systems, or anyone who is particularly sensitive to live probiotics.
Then there’s the logistical considerations. Because they’re no longer alive, they’re also far more stable and don’t require refrigeration, making them easier to store and more practical to incorporate into everyday routines. Postbiotics can be categorised into several distinct types — here’s a rundown of the main players.
The gut supporter: Short-chain fatty acids (SCFAs)
Short-chain fatty acids (SCFAs) have become a key buzzword when it comes to gut health. These digestive helpers such as butyrate, acetate, and propionate, are naturally produced when gut bacteria break down dietary fibre from everyday foods like broccoli, lentils and wholegrains and they play a vital role in maintaining gut health.Butyrate, in particular, is an important energy source for the cells lining the colon and is known to support the integrity of the gut lining.
SCFAs have also been linked to anti-inflammatory effects, metabolic health, and even brain function, highlighting the powerful gut-brain connection. One study found that exercise helped to promote the growth of bacteria that produces butyrate, reinforcing the idea that lifestyle choices can directly influence gut health.
The immune helper: Polysaccharides
Bacterial polysaccharides may sound technical, but they fall neatly into the postbiotic category, interacting directly with the gut and immune system. These complex carbohydrates form part of the cell walls of bacteria and are naturally abundant in fermented plant foods such as kimchi and sauerkraut.
Unlike prebiotics (which feed gut bacteria), bacterial polysaccharides work by communicating with immune cells in the gut, helping to regulate immune responses and support the integrity of the gut barrier. Emerging research suggests they may help strengthen the intestinal lining, reduce low-grade inflammation and promote immune balance — making them particularly interesting in the context of digestive health, allergies and certain skin conditions, where immune signalling plays a central role.
The energy booster: Bacterial metabolites
Gut bacteria don’t just support digestion, they also produce essential nutrients, including B vitamins, which play a key role in energy production, brain function, and overall metabolic health. These vitamins are considered postbiotics because even in the absence of live bacteria, the compounds they leave behind can still benefit the body.
Bacterial-derived B vitamins (like B12, B6, and folate) help convert food into energy, support healthy nerve function, and play a role in balancing mood. By acting as chemical messengers, they also influence communication between the gut and the brain, highlighting yet another way the microbiome impacts whole-body health.
Incorporating fibre-rich foods, fermented vegetables, and certain fermented dairy products like kefir into your diet can support the growth of these vitamin-producing bacteria, while emerging research suggests that their metabolites can continue to work even if the bacteria themselves are no longer alive.
Three postbiotic buys
Root Postbiotic Starter Kit, £33, rootbiotics.co.uk
Ancient + Brave True Biome, £34, ancientandbrave.earth
Bio-Kult 3-in-1 Biotic Blend, £16.98, bio-kult.com
