Propionibacterium freudenreichii is a probiotic bacterium primarily known for its use in cheese production, but recent research supports its immunomodulatory effects, particularly in relation to the gut-associated lymphoid tissue (GALT), which includes Peyer’s patches. Several studies have demonstrated that P. freudenreichii can interact with the intestinal immune system. For example, in vitro and animal experiments have shown that this bacterium can enhance the production of anti-inflammatory cytokines (such as IL-10) and promote regulatory T cell activity, both of which are important in modulating immune responses in the intestines. Peyer’s patches, as lymphoid follicles in the small intestine, play a key role in the development of mucosal immunity. Research suggests that P. freudenreichii can stimulate dendritic cells within Peyer’s patches, contributing to the maturation of these immune tissues and the induction of oral tolerance. However, while there is growing scientific interest and some positive results, most evidence comes from preclinical models, with limited direct human clinical data specifically linking P. freudenreichii to enhanced function of Peyer’s patches. Thus, the scientific evidence is promising but not yet definitive, justifying a moderate evidence rating.