Lactobacillus salivarius is a probiotic bacterium commonly found in the human gastrointestinal tract. Its use in supporting the immune system, and specifically the Peyer’s patches, is based on a growing body of scientific research, although the evidence is still emerging and not definitive. Peyer’s patches are lymphoid follicles located in the small intestine that play a critical role in immune surveillance and the generation of immune responses to gut antigens.

Some animal studies and in vitro experiments have shown that L. salivarius can modulate immune activity in the gut. For example, it has been observed to enhance the production of immunoglobulin A (IgA)—an antibody crucial for mucosal immunity—often associated with activity in Peyer’s patches. A handful of studies in mice suggest that supplementation with L. salivarius leads to increased IgA-secreting cells in the intestinal mucosa, which are often generated in Peyer’s patches. Furthermore, L. salivarius can influence the balance of pro- and anti-inflammatory cytokines, potentially supporting gut immune homeostasis.

However, direct evidence in humans, specifically linking L. salivarius supplementation to enhanced function of Peyer’s patches, is limited. Most clinical research focuses on broad immune or gastrointestinal benefits rather than mechanisms involving Peyer’s patches specifically. Thus, while there is scientific rationale and some supportive data, the evidence base is not yet robust.