Probiotics and prebiotics are all the rage. But science has long since reached the next stage of microbiome research: postbiotics. These bioactive metabolic products of our gut bacteria exert their effects entirely without live microbes – and are therefore considered particularly safe, stable, and versatile. Current research shows that postbiotics can modulate the immune system, protect against infections, and even help with metabolic disorders. A look at the underestimated superstars of our gut.
What exactly are postbiotics?
Postbiotics are defined as "bioactive compounds that are formed in a matrix during fermentation and are beneficial to health". The term encompasses a wide variety of substances: short-chain fatty acids (SCFAs), enzymes, peptides, teichoic acids, peptidoglycan components, polysaccharides, cell wall proteins, and organic acids. Unlike probiotics, postbiotics do not contain live microorganisms, but only their metabolic products or cell components – which minimizes the risk of infections or unwanted immune reactions. .
A fundamental review article from 2020 in the journal Nutrients succinctly summarizes it: "Since postbiotics do not contain live microorganisms, the risks associated with their ingestion are minimized." This makes them particularly attractive for people with weakened immune systems or for use in early childhood.
The diverse mechanisms of action
Postbiotics exert their health-promoting effects through multiple pathways. A recent review article from October 2025 in ScienceDirect describes in detail their immunomodulatory, anti-inflammatory, and antimicrobial properties. .
Immunomodulation and anti-inflammatory effects
Postbiotics can specifically intervene in immune regulation. They strengthen the epithelial barrier function, regulate the balance between Th1 and Th2 immune responses, and promote the formation of regulatory T cells. . Particularly short-chain fatty acids such as butyrate, propionate and acetate – the most important representatives of postbiotics – not only supply the intestinal mucosal cells with energy, but also have an anti-inflammatory effect by blocking certain signaling pathways in immune cells. .
Protection against respiratory infections
One particularly exciting area of research is the so-called "gut-lung axis." The aforementioned review demonstrates that postbiotics can also influence the immune response in the respiratory tract via this axis. In preclinical models, postbiotics showed promising effects in diseases such as pneumonia, influenza, COVID-19, asthma, and allergic rhinitis: they strengthened the epithelial barrier, regulated the immune response, inhibited pathogenic biofilms, and enhanced the effectiveness of conventional therapies. .
Antibiotic-associated microbiome damage
One of the most sensational studies of recent months comes from January 2026. Researchers led by Jonas Schluter published the results of a randomized, placebo-controlled study with 32 patients who received oral antibiotics and probiotics in the journal Infection and Immunity. Half of the participants also received a fermentation-based postbiotic.
The result is impressive: At the end of antibiotic therapy, patients receiving postbiotics showed 40% higher bacterial alpha diversity in their stool than the placebo group. Particularly beneficial bacteria, such as obligate anaerobic Firmicutes (especially Lachnospiraceae), were enriched, while potentially pathogenic Escherichia/Shigella species remained reduced – even ten days after the end of treatment. The authors conclude: "Postbiotics could promote the health-associated microbiome composition and mitigate antibiotic-induced microbiome damage." .
Clinical applications: From the psyche to metabolism
Research on postbiotics has produced several clinical trials in recent months, investigating their therapeutic potential in various areas.
Mental health
A randomized, double-blind, placebo-controlled study from South Korea is currently investigating the effect of postbiotics on mood disorders in adults. Fifty-two participants aged 19 to 39 years with elevated scores on the Depression Scale (CES-D ≥ 16) received either a postbiotic (20 × 10^9 CFU/day) or a placebo for eight weeks. Changes in depressive symptoms, current mood (using Ecological Momentary Assessment), psychological stress, and the composition of the gut microbiome and its metabolites were measured. The study is still ongoing; initial results are expected at the end of 2026.
Metabolic health
Another recent study, published in January 2026 in the journal Nutrition , investigated the effect of the postbiotic pA1c®HI in obese people – with and without prediabetes. . 17 participants received a capsule containing 1 × 10^10 cells of the postbiotic or a placebo daily for twelve weeks.
The results are promising: In the postbiotic group, the HbA1c value decreased significantly by 0.22 percentage points compared to placebo. Although the differences in weight, BMI, and body fat did not reach statistical significance, clinically meaningful improvements were observed: Diastolic blood pressure decreased by 8.8 mmHg. Particularly interesting: In a post-hoc analysis of participants with prediabetes, the postbiotic showed clear trends towards lowering blood sugar, HbA1c, insulin resistance (HOMA-IR) and insulin levels. The authors conclude: "Postbiotics show promise for the treatment of glucose and lipid metabolism as well as for improving body composition in patients with obesity." .
Immunomodulation in vertebrates
An animal study, published in November 2025 in BMC Veterinary Research , investigated the immunomodulatory properties of three heat-inactivated Lactobacillus strains in a zebrafish model. Fish fed with postbiotics showed altered expression of important immune genes (Il1β and Ifn-γ) and significantly higher survival rates after infection with viral hemorrhagic septicemia virus (VHSV). Lactiplantibacillus plantarum HA-119 and Lactobacillus helveticus HA-122 proved particularly effective. The histological examinations confirmed the safety of the postbiotics – no changes were found in the intestinal mucosa. .
Advantages over probiotics
Postbiotics offer several key advantages over live probiotics. :
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Increased safety : No risk of translocation, infection, or excessive immune responses, especially in immunocompromised individuals.
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Greater stability : Longer shelf life and resistance to temperature, humidity and stomach acid.
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Clearly defined structure : Exact chemical composition enables precise dosing and standardized effectiveness.
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No horizontal gene transfer : No risk of transferring antibiotic resistance genes to pathogenic bacteria
Conclusion
Postbiotics are far more than a scientific trend – they represent a new generation of microbiome-based therapies. As bioactive metabolites of our gut bacteria, they exert immunomodulatory, anti-inflammatory, and antimicrobial effects without the risks of live microbes. Current research demonstrates their potential to protect against antibiotic-induced microbiome damage, support metabolic health, and possibly even treat mood disorders.
While probiotics introduce live bacteria into the gut, postbiotics directly provide the tools with which these bacteria can exert their beneficial effects – an elegant and safe strategy for the health of the gut, immune system and far beyond.
Official sources & studies:
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Postbiotics-A Step Beyond Prebiotics and Probiotics (Nutrients, 2020) - PubMed
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Postbiotics and extracellular vesicles: Mechanisms of action in respiratory infections (ScienceDirect, 2025)
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Effects of Postbiotics on Mood Disorders in Korean Adults (ClinicalTrials.gov, 2025)
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Postbiotic administration during antibiotic treatment increases microbiome diversity (Infection and Immunity, 2026) - PubMed
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Postbiotics and Their Potential Applications in Early Life Nutrition (IJMS, 2019) - PubMed
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Pre-, pro- and postbiotics – an introduction (ENT, 2025) – PMC
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Preliminary effect of the postbiotic pA1c®HI in glucose metabolism of obese individuals (Nutrition, 2026) - PubMed
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Postbiotics: An evolving term within the functional foods field (ScienceDirect, 2018)
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Immunomodulating properties of postbiotics from lactobacilli in zebrafish (BMC Veterinary Research, 2025)
