Your blood type influences which bacteria live in your gut.

The relationship between blood type and gut flora is rooted in the ABO gene, which dictates the expression of specific antigens. These antigens are not just found on red blood cells but are also secreted into the mucus lining of the digestive tract in about 80% of the population, known as 'secretors.' These sugar molecules act as attachment sites and nutrients for different bacterial species.A landmark study published in the journal 'Nature' in 2012 by researchers from the University of Helsinki found that the ABO blood group is a major driver of gut microbiota variation. For instance, individuals with Type A blood often have higher levels of 'Bifidobacterium' because these bacteria possess specialized enzymes to break down Type A antigens. In contrast, those with Type O blood lack these specific A or B sugar structures, which creates a different selective pressure on their microbiome.Research conducted at the University of Toronto has further explored how these interactions affect health outcomes like inflammatory bowel disease and metabolic syndrome. The presence or absence of specific antigens can determine how well a person resists certain pathogens like 'H. pylori' or 'E. coli.' This biological mechanism explains why people with different blood types may react differently to the same diet or probiotic supplement. Understanding these associations helps scientists develop personalized nutrition plans based on an individual's genetic profile.