What role does FUT2 play in gut health?

FUT2 (fucosyltransferase 2) determines secretor status: about 80 % of individuals are 'secretors' and express ABO blood group antigens in bodily fluids. These antigens act as receptors for gut bacteria and viruses. Non-secretors (carrying loss-of-function FUT2 variants) show altered gut microbiome composition – fewer Bifidobacteria, more potentially pathogenic taxa – and increased susceptibility to norovirus infection and Crohn’s disease. Evidence comes mainly from observational and GWAS studies; RCTs are lacking. Effect sizes are modest, and individual prediction is limited. A DNA test can identify FUT2 variants, but the clinical utility for diet or health management is low. Gut health is more strongly shaped by diet, medications, and lifestyle. Safety note: FUT2 variants are not a diagnosis; persistent gastrointestinal symptoms warrant medical evaluation.