In Vitro Assessment of the Prebiotic Effects of Poria Cocos Polysaccharides Using Fecal Microbiota from Normal-Weight and Obese Children

Poria cocos polysaccharides (PCP) are recognized as potential prebiotics with documented metabolic benefits in adults. However, their impact on the gut microbiota of children remains unclear. This study aimed to evaluate the effects of PCP versus inulin (INL) on the gut microbiota and bacterial metabolites in normal-weight children (CON) and obese children (OB). In vitro fermentation was conducted using fecal samples pooled from five normal-weight children and five obese children, respectively. The samples were incubated with PCP, INL, or a blank control under anaerobic conditions at 37 °C for 24 h. After fermentation, the effects of PCP and INL on gut microbiota were evaluated using 16S rRNA sequencing. Bacteria-derived metabolites were measured using targeted metabolic profiling. Single-strain validation was performed to confirm effects on key bacterial taxa. PCP supplementation promoted the growth of Bifidobacterium and Limosilactobacillus in both normal-weight and obese children, accompanied by a rise in acetic acid production, particularly in normal-weight children. Compared to INL, PCP showed similar but slightly weaker effects on Bifidobacterium growth and short-chain fatty acids (SCFAs) production, but more strongly stimulated Limosilactobacillus growth. Notably, PCP also stimulated the production of indolelactic acid in both obese and normal-weight children. Correlation analysis indicated that Bifidobacterium and Limosilactobacillus were positively associated with acetic acid, lactic acid, and indolelactic acid, and negatively associated with tryptophan. Single-strain fermentation supported the community-level findings. PCP and INL both modulate gut microbiota and metabolic profiles in children, with PCP demonstrating a distinct prebiotic profile. Notably, PCP increased health-associated metabolites such as acetic acid and indolelactic acid, which are implicated in gut barrier support, immune modulation, and metabolic regulation. These findings suggest PCP may be considered a functional food component for supporting gut health in children, warranting further research.