β-Glucan Alone or Combined with Lactobacillus acidophilus Positively Influences the Bacterial Diversity and Metabolites in the Colonic Microbiota of Type II Diabetic Patients.

β-Glucan is a fermentable polysaccharide with prebiotic properties that has been shown to improve metabolic indicators. This study evaluated the effects of spent brewer's yeast β-glucan (BGL) and Lactobacillus acidophilus LA-5 (10 CFU/g) (LA5) alone and in combination (LA5-BGL) on the composition of the fecal microbiome of adults with type 2 diabetes mellitus (T2DM) using the Human Gut Microbial Ecosystem Simulator (SHIME®). Short-chain fatty acids (SCFAs), ammonium ions, and cytokines (IL-6 and IL-10) were measured. BGL, LA5, and LA5-BGL increased (p < 0.05) the richness and diversity of microbial communities in the gut microbiome of individuals with T2DM. All treatments increased (p < 0.05) the abundance of Bacteroides, Alistipes, Lactobacillus, Subdoligranulum, and Acidaminococcus, along with increased (p < 0.05) production of SCFAs and anti-inflammatory cytokine (IL-10) compared to the control group. BGL treatments showed a greater increase in microbial diversity, SCFAs levels (butyric, propionic, and acetic acid), and the anti-inflammatory cytokine (IL-10). LA5 showed the highest decrease in ammonium ion levels. Results indicate that BGL may have a prebiotic and immunomodulatory effect on the fecal microbial community and metabolic indicators in adults with type 2 diabetes mellitus (T2DM). Findings underscore the role of BGL as a prebiotic food.