Triacetin and a Mushroom Blend Restore Butyrate Production by IBS Microbiomes Ex Vivo, Thus Promoting Barrier Integrity

Irritable Bowel Syndrome (IBS) is a common gastrointestinal disorder, characterized by abdominal pain, altered bowel habits (diarrhea and/or constipation) and a dysbiosis of the gut microbiome. This dysbiosis is difficult to restore via fiber supplementation, which typically promotes gas production, potentially worsening IBS symptoms. We therefore studied how two novel products, triacetin (TA; REBiome™) and a mushroom blend (MB; Hōlistiq™), modulate the microbiome of IBS subjects (<i>n</i> = 8) using the ex vivo SIFR^® (Systemic Intestinal Fermentation Research) technology combined with a co-culture of epithelial/immune (Caco-2/THP-1) cells. First, the IBS microbiomes revealed large interpersonal variability and an IBS-associated dysbiosis. TA increased the beneficial metabolites acetate and butyrate (~<i>Anaerobutyricum soehngenii, Mediterraneibacter</i>_A <i>butyricigenes</i>, <i>Faecalibacterium prausnitzii</i>). Moreover, MB stimulated a wide range of gut microbes and additionally promoted propionate. Despite more strongly increasing total short-chain fatty acid (SCFA) levels, TA induced significantly less gas production than MB. Mechanistically, acetate with TA was derived from hydrolysis, a process that indeed does not induce gas production. Notably, both TA and MB enhanced gut barrier integrity (transepithelial electrical TEER), which is related to lower symptom severity in IBS patients. Overall, our findings highlight the product-specific microbiome modulation and potential of MB, TA or combinations thereof as dietary interventions for managing IBS symptom severity.