The fermentation supernatant from King Oyster mushroom may exert anti-inflammatory effects, supporting the gut barrier when exposed to damaging secondary bile acids, says a new study.
The in vitro study, published in Nutrients, highlighted the potential of the fermentation supernatant of King Oyster mushroom (Pleurotus eryngii), also known as King Trumpet mushroom, for managing gut barrier dysfunction or "leaky gut."
"We have elucidated a dual protective capacity of FS-PEWS [Pleurotus eryngii mushroom fermentation supernatant], specifically its remarkable ability to preserve tight junction integrity while concurrently modulating both paracellular and transcellular permeability under the stress of secondary bile acid exposure," wrote researchers from the Nutrition-Gut-Brain Interactions Research Centre at Örebro University and other institutions in Athens, Greece.
They noted that their findings "herald a novel mechanistic paradigm for the therapeutic application of products based on P. eryngii mushrooms, positioning them as a highly promising approach for the clinical management of intestinal permeability disorders while also mitigating systemic inflammatory cascades."
The intestinal barrier must allow dietary nutrients to be absorbed while defending the body from pathogens and harmful external agents. This process depends on the integrity of the gut membrane and its tight junctions.
Leaky gut is as it sounds: An undesirable situation when toxic bacterial components can pass from the gut lumen into the blood. It may occur due to inflammation, illness, medications and other factors. Growing evidence suggests that secondary bile acids in high-fat diets are detrimental to gut barrier function and may lead to leaky gut.
Deoxycholic acid is a secondary bile acid formed through microbial conversion. It has cytotoxic and inflammatory effects, driving oxidative stress and disrupting the gut barrier and its tight junctions. High sodium deoxycholate (SDC) levels, the sodium salt of deoxycholic acid, are linked to ulcerative colitis and colorectal cancer.
Diet is critical in shaping the gut microbiome and supporting its functions. P. eryngii is a king oyster mushroom with fiber, protein and bioactive compounds that may promote gut barrier health.
Beta-glucans are the predominant source of fiber in P. eryngii, acting as a prebiotic for microbial fermentation.
The current study notes that the mushrooms' bioactive polysaccharides and secondary metabolites may help maintain the gut barrier "by modulating tight junction dynamics." In addition, P. eryngii may inhibit and downregulate inflammatory agents such as NF-kB.
Noting the previously reported beneficial effects of P. eryngii, the researchers aimed to investigate the ability of P. eryngii mushroom fermentation supernatant (FS) to counteract SDC's damaging impact on the gut barrier and immune homeostasis.
Researchers used fermentation supernatants of P. eryngii. The supernatant is the clear liquid overlying the material after settling, precipitation or centrifugation.
They generated the supernatants by fermenting fecal samples from five healthy elderly donors in vitro for 24 hours. The fermentation substrate was powdered mushrooms of the P. eryngii strain. Following fermentation, the samples were centrifuged to separate the supernatants.
The study also used an in vitro Caco-2 cell model and ex vivo colonic biopsies from healthy adult donors, exposing them to SDC to induce a disruption in intestinal barrier permeability.
In Caco-2 cells, FS-PEWS restored zonula occludens-1 (ZO-1) and claudin-1 levels that SDC had downregulated.
The colonic biopsies from healthy adults "FS-PEWS maintained tissue integrity and selectively mitigated transcellular permeability without affecting paracellular permeability when combined with the stressor," the researchers wrote.
"Additionally, FS-PEWS exhibited potent anti-inflammatory effects, reducing pro-inflammatory cytokines, e.g., TNF-α, IL-6 and IL-1β and modulating receptor-mediated pathways, i.e., TLR-4, dectin-1," they added.
The study noted that the findings pave the way for future research to refine the understanding of specific bioactives in FS-PEWS that may help manage conditions related to gut barrier dysfunction, dysbiosis and inflammation.
Source: Nutrients 2025, 17(4), 694. doi: 10.3390/nu17040694. "Pleurotus eryngii Mushrooms Fermented with Human Fecal Microbiota Protect Intestinal Barrier Integrity: Immune Modulation and Signalling Pathways Counter Deoxycholic Acid-Induced Disruption in Healthy Colonic Tissue". Authors: E.N. Kerezoudi et al.