Scientists are discovering that your blood type (A, B, AB, or O) might influence which bacteria live in your gut and how healthy you are. Your body has a genetic trait called “secretor status” that determines whether your blood type shows up on the lining of your digestive system. When it does, it acts like a landing pad for certain bacteria. Researchers found that different blood types attract different bacteria, which could affect your risk of getting sick or developing diseases. While these findings are exciting and could lead to personalized health treatments based on your blood type, scientists say more research is needed to prove these connections work in real people.

The Quick Take

  • What they studied: How your blood type and a genetic trait called secretor status influence which bacteria live in your gut and whether this affects your health
  • Who participated: This was a review of existing research rather than a new study with participants. Scientists looked at what other researchers had already discovered about blood types, genetics, and gut bacteria
  • Key finding: Your blood type appears to act like a magnet for certain types of gut bacteria. About 80% of people are ‘secretors,’ meaning their blood type shows up in their digestive system and attracts specific bacteria. The remaining 20% have different bacterial patterns
  • What it means for you: In the future, doctors might be able to recommend specific probiotics or dietary changes based on your blood type to improve your gut health. However, this is still early research, and you shouldn’t change your diet or take new supplements based on blood type alone without talking to your doctor

The Research Details

This research is a comprehensive review, meaning scientists read and analyzed many previous studies about blood types, gut bacteria, and health. They didn’t conduct their own experiment with people. Instead, they looked for patterns in what other researchers had discovered and tried to connect the dots between blood type, a genetic trait called secretor status, and the bacteria living in our digestive systems.

The researchers focused on how blood type antigens (special markers on your cells) work in the gut. They explained that in secretor individuals, these blood type markers appear on the mucus lining of the intestines, where they can interact with bacteria. They reviewed evidence showing that different bacteria prefer to attach to different blood types, similar to how a key fits into a specific lock.

The scientists also examined how secretor status affects which bacteria can survive and thrive in your gut, and how this might influence your risk of getting infections, developing metabolic diseases like diabetes, or experiencing autoimmune problems like inflammatory bowel disease.

This type of review is important because it helps scientists see the big picture. By combining findings from many studies, researchers can identify patterns that might not be obvious from looking at just one study. This approach helps determine whether new ideas are worth investigating further with larger, more controlled experiments. Understanding these connections could eventually lead to personalized medicine—treatments tailored to your individual genetics.

This is a review article, which means it synthesizes existing knowledge rather than presenting new experimental data. The authors appropriately note that current evidence is preliminary and that more rigorous clinical studies are needed. The research was published in a peer-reviewed scientific journal, meaning other experts reviewed it before publication. However, because this isn’t original research with human participants, readers should understand that the connections described are still being investigated and aren’t yet proven enough to change medical practice

What the Results Show

The research reveals that blood type appears to influence gut bacteria composition. Certain bacteria, including Bacteroides, Eubacterium, and Faecalibacterium species, show preferences for specific blood types. The mechanism appears to work through several pathways: bacteria use blood type antigens as attachment sites (like docking stations), as food sources (the bacteria can break down the sugars in blood type markers), and through competitive exclusion (where some bacteria outcompete others based on blood type compatibility).

Secretor status emerged as particularly important. About 80% of people are secretors, meaning their blood type antigens appear on the intestinal lining where bacteria can interact with them. The remaining 20% are non-secretors with different bacterial patterns. Non-secretors showed altered populations of Bifidobacterium bacteria and were less susceptible to norovirus (a stomach bug) because the virus couldn’t attach as easily to their intestinal lining.

The research suggests these microbial differences could affect disease risk. Blood type and secretor status appear to influence susceptibility to infections, metabolic diseases (like obesity and diabetes), and autoimmune conditions (like inflammatory bowel disease). The exact mechanisms are still being studied, but the connection between genetics, bacteria, and health appears real.

The review identified that secretor status impacts overall bacterial diversity in the gut. Secretors tend to have different bacterial communities than non-secretors. The research also suggests that probiotic effectiveness (beneficial bacteria you might take as supplements) could depend on your blood type and secretor status, meaning a probiotic that helps one person might not help another based on their genetics. Additionally, the findings suggest that blood type might influence how well your gut bacteria can extract nutrients from food and how they interact with your immune system

This research builds on decades of observations that blood type affects health in various ways. Scientists have long known that blood type influences disease risk, but the mechanism was unclear. This review connects those observations to gut bacteria, providing a biological explanation for why blood type matters. The findings align with growing evidence that the microbiome (your gut bacteria) plays a central role in health and disease, and they extend this understanding by showing that host genetics directly shape which bacteria live in your gut

The authors clearly state that current evidence is preliminary and mostly based on observational studies rather than rigorous controlled experiments. Most research has been done in laboratory settings or small studies, not large populations. The review doesn’t include new data from human trials testing whether blood-type-based interventions actually improve health. The biological mechanisms are still being worked out—scientists understand some pathways but not all. Additionally, the gut microbiome is influenced by many factors beyond blood type, including diet, antibiotics, stress, and exercise, making it difficult to isolate blood type’s specific effect

The Bottom Line

Current evidence suggests blood type and secretor status may influence gut health, but recommendations remain exploratory. At this stage, the evidence is too preliminary to recommend changing your diet or taking specific probiotics based solely on blood type. If you’re interested in optimizing your gut health, focus on proven strategies: eat a diverse diet rich in fiber, limit processed foods, manage stress, get regular exercise, and use antibiotics only when necessary. If you want to explore blood-type-based approaches in the future, discuss this with your doctor or a registered dietitian who can help interpret new research as it emerges. Confidence level: Low to moderate—this is an emerging area requiring validation

This research is most relevant to people interested in precision medicine and personalized health approaches. It may be particularly interesting to those with a family history of autoimmune diseases, metabolic disorders, or recurrent infections. People considering probiotic supplements might eventually benefit from this research. However, this shouldn’t concern people with well-managed health conditions or those who prefer to wait for more definitive evidence. This research is not yet actionable for most people and shouldn’t replace standard medical advice

If blood-type-based microbiome interventions prove effective, benefits would likely take weeks to months to appear, similar to other dietary or probiotic changes. However, don’t expect immediate results. Realistic expectations would be gradual improvements in digestion, energy, or immune function over 8-12 weeks if interventions are eventually developed and proven effective. Most experts estimate it will be 5-10 years before this research translates into clinical recommendations

Want to Apply This Research?

  • Track your blood type and secretor status (if known) in your profile, then monitor digestive symptoms (bloating, regularity, energy levels) weekly using a simple 1-10 scale. This creates a baseline for future comparison if personalized recommendations become available
  • While waiting for blood-type-specific guidance, use the app to track general gut health habits: daily fiber intake, water consumption, probiotic/prebiotic foods, and stress levels. Log any digestive changes to identify personal patterns. This data will be valuable when more targeted recommendations emerge
  • Establish a long-term tracking system that records your blood type, any genetic testing results, digestive health markers, and dietary patterns. Create monthly summaries to identify trends. This personalized data will help you and your healthcare provider evaluate whether future blood-type-based interventions work for you specifically

This research is a review of existing studies and represents preliminary, exploratory science. The connections between blood type, secretor status, and gut health are still being investigated and are not yet established enough to guide medical decisions. Do not change your diet, start new supplements, or make other health changes based on blood type without consulting your doctor or a registered dietitian. This information is educational only and should not replace professional medical advice. If you have concerns about your digestive health or disease risk, speak with your healthcare provider about evidence-based approaches appropriate for your individual situation.