While many people are familiar with the basic concept of blood types—A, B, AB, and O—few are aware that these classifications may have broader implications beyond transfusion compatibility. Emerging research suggests that your blood type may influence your susceptibility to certain diseases and health conditions. Although it is not possible to change your blood type, being informed about your specific type may help you take proactive steps to mitigate associated health risks.

Understanding Blood Types

Blood type is determined by the presence or absence of specific antigens on the surface of red blood cells. These include the A and B antigens, as well as the Rh factor, which classifies blood as either positive or negative. For example, a person with both A antigens and the Rh factor would be classified as A positive (A+). According to the American Red Cross, the distribution of blood types varies by population group, but O positive is the most common globally. In fact, 38% of the population has O positive blood. While blood type has long been critical in emergency medicine and transfusion science, recent studies indicate it may also offer insights into disease risk profiles.

Cognitive Function and Neurological Health

One of the most striking findings regarding blood type and cognitive health comes from a 2014 study published in Neurology. Researchers found that individuals with blood type AB had an 82% higher risk of cognitive impairment compared to those with other blood types, especially type O. This study suggested that blood type might influence blood flow or clotting properties, which could, in turn, affect brain health over time.

Conversely, individuals with type O blood appear to enjoy some degree of protection against neurological conditions such as Alzheimer’s disease and memory loss. The hypothesis is that type O individuals may have a more favourable vascular profile, reducing their risk of damage to the brain’s blood vessels.

Gastrointestinal and Digestive Disorders

Blood type may also influence gastrointestinal health. According to the American Cancer Society people with type A blood have a significantly higher risk of developing stomach cancer than those with type O blood. Similarly, individuals with type O blood are more prone to peptic ulcers, potentially due to their heightened immune response to Helicobacter pylori, the bacterium responsible for most ulcers. On the other hand, types A and AB may be less susceptible to peptic ulcers but show increased vulnerability to other gastrointestinal issues, including gastritis and certain infections. These patterns are believed to stem from variations in mucosal immunity and inflammatory response mechanisms among different blood types.

Cardiovascular and Metabolic Risks

Blood type may also influence heart health and metabolic function. A comprehensive study in the National Library of Medicine indicated that individuals with non-O blood types (A, B, and AB) face a higher risk of coronary artery disease due to elevated levels of Von Willebrand factor, a protein involved in blood clotting. Increased clotting risk can lead to events such as heart attacks or strokes, especially in individuals with other underlying risk factors. According to research type AB blood has been associated with an increased likelihood of experiencing a stroke. This elevated risk is attributed to the same clotting tendencies seen in coronary heart disease. Additionally, a study published in Medscape shows that the risk of type 2 diabetes for those with blood type O is low, while those with type B-positive blood has the highest risk of developing type 2 diabetes.

Debunking the Blood Type Diet

The concept of a “blood type diet,” popularized by alternative health circles, proposes that eating specific foods based on your blood type can optimise health. However, a 2014 study published in PLOS One found no scientific basis for these claims. The researchers concluded that while blood type may affect disease risk to a small extent, it does not dictate dietary needs. Therefore, individuals should focus on universally accepted principles of healthy eating—such as consuming a balanced diet rich in whole grains, lean proteins, fruits, and vegetables—rather than tailoring their diet based on blood type alone.

Lifestyle Matters More

Although blood type may confer modest advantages or disadvantages in terms of disease susceptibility, it is not destiny. Lifestyle choices such as maintaining a healthy weight, exercising regularly, managing stress, avoiding tobacco, and limiting alcohol intake play a far more significant role in determining long-term health outcomes. Family history, environmental exposure, and genetic factors also contribute to disease risk and should be considered in tandem with blood type. Regular check-ups and personalised advice from a healthcare professional are essential for disease prevention and early intervention.

Conclusion

While scientific evidence indicates that blood type can influence susceptibility to certain health conditions—including cognitive decline, cardiovascular disease, gastrointestinal disorders, and metabolic issues—the overall impact is modest. Understanding your blood type can be an added tool in your health arsenal, but it should not replace evidence-based preventative care and healthy practices. Lifestyle factors such as diet, exercise, and preventative care outweigh blood type in determining health.

References

• American Academy of Neurology. (2014). Can your blood type affect your memory? https://www.aan.com/PressRoom/Home/PressRelease/1306
• American Cancer Society. (2021). Stomach cancer risk factors. https://www.cancer.org/cancer/types/stomach-cancer/causes-risks-prevention/risk-factors.html
• American Red Cross. (n.d.). Why is type O blood so important? Here’s why blood type matters. https://www.redcrossblood.org/donate-blood/blood-types/o-blood-type.html
• Fedhealth. (2016). How to change bad eating habits. https://www.fedhealth.co.za/articles/how-to-change-bad-eating-habits/
• Haemost, J. T. (2014). ABO blood type and stroke risk. National Library of Medicine. https://pmc.ncbi.nlm.nih.gov/articles/PMC4913462/
• National Library of Medicine. (2017). Non-O blood groups associated with higher risk of heart attack. https://pmc.ncbi.nlm.nih.gov/articles/PMC5558144/
• Tucker, M. E. (2025). Type 2 diabetes risk lower for blood type O. Medscape. https://www.medscape.com/viewarticle/836944?form=fpf
• Wang, J., et al. (2014). ABO genotype, “blood-type” diet and cardiometabolic risk factors. PLOS ONE, 9(1), e84749. https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0084749&type=printable
• Women’s Brain Health Initiative. (n.d.). Blood type linked to Alzheimer’s risk. https://womensbrainhealth.org/think-tank/think-about-it/blood-type-linked-to-alzheimers-risk