Maternal purified fiber supplementation-enriched <italic>Akkermansia muciniphila</italic> regulates lactation and offspring growth via the gut-mammary axis

Maternal fiber intake alters the maternal gut microbiota and metabolites, which benefits offspring health through unclear mechanisms. Using a sow model, the study showed that supplementing with purified fiber (cellulose:guar gum=3:1) increased weaning weight and resistance to LPS-induced intestinal injury. Milk analysis revealed higher levels of immunoglobulins and milk fat. Fecal microbiota transplantation (FMT) from fiber-fed sows to mice replicated these benefits, increasing milk fat, immunoglobulins, and pup growth. Akkermansia muciniphila (AKK) abundance was positively associated with milk quality in both models. Supplementing with AKK mimicked the effects of fiber, boosting milk fat and immunoglobulins. In in vitro experiments with HC11 mammary epithelial cells showed that AKK metabolites enhanced milk fat synthesis and immunoglobulin transporter expression. Metabolite analysis indicated that AKK influences mammary gland function by increasing acetate and propionate levels, with acetate promoting milk fat synthesis via GPR43 and propionate regulating immunoglobulin transport through GPR41. Therefore, maternal fiber intake promotes intestinal AKK abundance, increases short-chain fatty acids (SCFAs) production, and influences lactation via GPR41/43 signaling.