Effects of Galacto-Oligosaccharide Supplementation on Cecal Microbiota, Phospholipid and Aromatic Amino Acid Metabolism in Mice

Galacto-oligosaccharides (GOSs) are well-recognized for their beneficial effects on intestinal health, yet their regulatory impacts on the metabolic dynamics of other intestinal metabolites remain elusive. In this study, 24 male C57BL/6 mice were assigned to three groups: control (CON), low-dose GOS (L-GOS; 500 mg/kg body weight), and high-dose GOS (H-GOS; 800 mg/kg body weight). Following a 4-week intervention, the cecal contents were analyzed to characterize the bacterial community structure and metabolic profiles. Results indicated that GOS supplementation significantly increased the ACE and Chao1 indices of cecal bacteria. Specifically, L-GOS led to notable enrichment of the <i>[Eubacterium] brachy</i> group, <i>Coriobacteriaceae UCG-002</i>, <i>Faecalimonas</i>, and the <i>[Eubacterium] siraeum</i> group, whereas H-GOS significantly increased the abundance of <i>Clostridium</i>, <i>Ruminiclostridium</i>, <i>Thomasclavelia</i>, <i>Adlercreutzia</i>, and <i>Faecalimonas</i>. Metabolomic profiling revealed that L-GOS profoundly reduced levels of phosphatidylethanolamine, phosphatidylcholine and their downstream metabolites, while inhibiting the conversion of sphingolipids to ceramides. The changes in phospholipid derivatives imply enhanced intestinal epithelial integrity, supporting intestinal homeostasis. GOS intervention also decreased phenylacetic acid content. L-GOS increased the 4-hydroxyphenylpyruvic acid content, whereas H-GOS reduced 4-hydroxyphenyllactic acid levels. Notably, H-GOS significantly up-regulated the production of indole-3-acetic acid, a tryptophan-derived microbial metabolite with multiple biological activities. Collectively, these findings provide insights and potential targets for future research on GOS application in intestinal health interventions.