How are FUT2 and Darmgesundheit related?

FUT2 and gut health are linked via the secretor status. The FUT2 gene encodes a fucosyltransferase that determines whether ABH blood group antigens are secreted into bodily fluids like saliva and gut mucus. Secretors (active enzyme) and non-secretors (inactive) show distinct gut microbiota compositions. Non-secretors tend to have lower bacterial diversity, fewer beneficial Bifidobacteria, and higher levels of potentially harmful bacteria. This has been associated with increased risk of Crohn's disease, irritable bowel syndrome, and recurrent urinary tract infections. Evidence comes from human observational studies and GWAS, showing moderate effect sizes. The relationship is not deterministic; diet, lifestyle, and other genetic factors strongly modulate gut health. A FUT2 test can provide a piece of the puzzle but should not be used alone for clinical decisions. The evidence level is human-moderate.