Immunoglobulin G (IgG) is the most abundant antibody in human serum and plays a crucial role in immune defense, including at mucosal surfaces such as the gut. Peyer’s patches are lymphoid follicles located in the small intestine, important for the detection of pathogens and initiation of mucosal immune responses. Scientific studies, particularly in animal models, have demonstrated that IgG can interact with antigens in the gut lumen, neutralize pathogens, and facilitate their clearance, thereby supporting mucosal immunity. Oral administration of IgG preparations (for example, derived from bovine colostrum or serum) has been studied for its potential to bind and neutralize gut pathogens, and some commercial products use this principle to support gastrointestinal health.

Although there is evidence showing that orally administered IgG can survive passage through the gastrointestinal tract and interact with intestinal immune components, including Peyer’s patches, the evidence in humans is limited and primarily comes from preclinical studies or small clinical trials. The mechanism involves IgG-antigen complexes being taken up by M cells in Peyer’s patches, potentially enhancing antigen presentation and modulating local immune responses. However, more robust clinical trials are needed to fully validate efficacy and clarify the extent of benefit specific to Peyer’s patches. Thus, the use of IgG to support the Peyer’s patches body system has some scientific basis, but current human evidence is moderate.