Vitamin D plays a crucial role in the modulation of the immune system, and there is growing scientific evidence supporting its involvement in gut-associated lymphoid tissue (GALT), which includes Peyer’s patches. Peyer’s patches are lymphoid follicles in the small intestine that are essential for immune surveillance of intestinal contents and the generation of immune responses to pathogens.

Several studies indicate that vitamin D receptors are highly expressed in immune cells found in Peyer’s patches. Vitamin D has been shown to influence the function of dendritic cells, T cells, and B cells within these patches, promoting immune tolerance and enhancing mucosal immunity. For example, vitamin D can induce regulatory T cells and modulate the secretion of immunoglobulin A (IgA), a key antibody in mucosal immunity. Animal models have demonstrated that vitamin D deficiency impairs gut barrier function and increases susceptibility to intestinal inflammation, further implicating vitamin D in the maintenance of Peyer’s patch structure and function.

While most evidence comes from basic science and animal studies, and direct human studies are limited, the mechanistic links between vitamin D and the health of Peyer’s patches are biologically plausible and increasingly recognized. Thus, scientific evidence supports a moderate role for vitamin D in the maintenance and regulation of Peyer’s patches and, by extension, gut immune health.