Vitamin A is scientifically validated as important for the function and development of Peyer’s patches, which are specialized lymphoid follicles found in the small intestine and play a critical role in gut immunity. Multiple studies have shown that vitamin A, through its active metabolite retinoic acid, is essential for the maintenance of the gut-associated lymphoid tissue (GALT), including Peyer's patches. Retinoic acid influences the homing of immune cells, particularly T and B lymphocytes, to the intestinal mucosa, and supports the differentiation of immune cells such as dendritic cells and IgA-producing B cells within Peyer's patches. Animal studies have demonstrated that vitamin A deficiency leads to underdeveloped Peyer's patches, impaired mucosal immunity, and increased susceptibility to intestinal infections. Moreover, vitamin A supplementation in deficient individuals restores mucosal immune responses and the structural integrity of Peyer’s patches.

Human studies, though more limited, support the role of vitamin A in enhancing mucosal immunity, especially in contexts of deficiency. Global health organizations recommend vitamin A supplementation in populations at risk of deficiency to support overall immune function, including the gut immune system. Thus, the use of vitamin A to support Peyer’s patches and related gut immunological functions is grounded in robust preclinical evidence and some clinical data, justifying its use in this context.