Lactobacillus acidophilus is a probiotic bacterium commonly found in the human gut microbiota and frequently used in dietary supplements. Its use to support Peyer's patches—specialized lymphoid follicles in the small intestine involved in immune surveillance and gut immunity—has some scientific basis. Several animal and in vitro studies suggest that L. acidophilus can modulate immune responses associated with Peyer’s patches. For example, research shows that oral administration of L. acidophilus can increase the number and activity of immune cells in Peyer’s patches, enhancing the secretion of IgA antibodies, which play a crucial role in mucosal immunity (Azad et al., 2018).

However, most evidence comes from animal studies or ex vivo experiments using murine or human cell cultures. Direct clinical trials in humans specifically measuring changes in Peyer’s patch function after L. acidophilus supplementation are lacking. Nonetheless, the general ability of probiotics—particularly Lactobacillus species—to modulate gut-associated lymphoid tissue (GALT) and improve mucosal immunity lends moderate support to the claim. Thus, while not conclusive, the use of L. acidophilus for supporting immune functions related to Peyer’s patches is scientifically plausible and partially validated by current research, but further human studies are needed for stronger evidence.