MFGM may be capable of modulating immune function in the gut through distinct but potentially complementary mechanisms. Glycosylated proteins (MUC-1, MUC-15, butyrophilin, and lactadherin) and glycosylated sphingolipids from MFGM may promote the development of healthy gut microbiota by favoring beneficial Bifidobacterium species. Another key to the immunomodulatory function of MFGM may be that its structure is similar to that of the intestinal cell membrane, allowing human milk glycans (including those on glycoproteins and glycolipids) to competitively inhibit the binding of pathogens (bacteria, viruses, even toxins) to host cells.
A number of preclinical studies have demonstrated inhibitory effects of MFGM against several pathogens. Both whole bovine MFGM and its extracted lipid components were found to exhibit dose-dependent inhibition of rotavirus infectivity in vitro. Antibacterial effects of MFGM have included decreased gastric colonization and inflammation after H. pylori infection in mice; inhibition of shiga toxin gene expression by E. coli O157:H7; and decreased colonization and translocation of L. monocytogenes. Mice that were fed prophylactically with bovine whey glycoprotein fraction, including MFGM proteins, did not develop diarrhea after exposure to rotavirus.