Safety evaluation of yeast β-glucan at elevated dose levels: toxicological and gut microbiota analyses

This study evaluated the safety and gut microbiota effects of high-dose yeast β-glucan (YBG). In the acute toxicity assay, the LD₅₀ exceeded 6.0 g/kg BW with no mortality. The 90-day subchronic study revealed no toxicologically relevant effects on clinical signs, body weight, hematology, serum chemistry, or histopathology at doses up to 3.0 g/kg BW; transient parameter alterations were within reference ranges and showed no delayed toxicity post-recovery. Developmental toxicity assessment (up to 2.84 g/kg BW) showed no adverse effects on maternal health, reproduction, or fetal development. Genotoxicity assays were negative. 16S rRNA sequencing indicated YBG did not disrupt microbial diversity; α-diversity remained stable, while β-diversity showed subtle shifts. Taxonomic analysis revealed increased relative abundance of beneficial genera (Lactobacillus, Akkermansia) without enrichment of pathogens. Collectively, these results demonstrate a wide safety margin for YBG under the tested conditions.