Oligosaccharides are a class of carbohydrates found naturally in foods such as onions, garlic, leeks, and chicory root, as well as added to functional foods as prebiotics. The Peyer's patches are specialized lymphoid follicles located in the small intestine and play a crucial role in the gut-associated lymphoid tissue (GALT), which is involved in immune surveillance and response.

Scientific studies have demonstrated that certain oligosaccharides, especially prebiotic types like fructooligosaccharides (FOS) and galactooligosaccharides (GOS), can modulate gut microbiota composition. This modulation promotes the growth of beneficial bacteria (such as Bifidobacteria and Lactobacilli), which in turn interact with the immune system, including Peyer's patches. Animal and in vitro studies show that oligosaccharide supplementation can enhance antigen sampling and immune cell activation within Peyer's patches, thereby supporting mucosal immunity. Some research suggests that prebiotic oligosaccharides increase the production of short-chain fatty acids (SCFAs), which have immunomodulatory effects on the gut environment and may strengthen the barrier and immune function associated with Peyer’s patches.

However, direct clinical evidence in humans specifically linking oligosaccharide intake to enhanced Peyer's patch function is limited. Most evidence is extrapolated from animal models and studies of general gut immunity. Thus, while there is a plausible scientific basis and some supporting data, the evidence is moderate rather than strong.