Your blood type plays a role in more than just transfusions. Recent research suggests it may also influence your risk of developing certain health conditions, including stroke. While it’s not the only factor that matters, understanding the connection between blood type and stroke risk can give you a clearer picture of your overall health.
People with blood type A may face a slightly higher risk of early-onset ischemic stroke. A study published in 2022 in the journal Neurology analyzed genetic data from over 16,000 stroke patients and nearly 600,000 controls. The researchers found that individuals with type A blood were 16% more likely to experience a stroke before the age of 60 compared to those with other types. One reason may involve clotting. People with type A blood tend to have higher levels of a protein called von Willebrand factor, which helps blood clot. While this is important for healing, it can also increase the risk of clot formation in blood vessels, potentially leading to a stroke.
Though type AB is the rarest blood type, some research suggests it may carry one of the highest stroke risks. A 2014 study from the University of Vermont found that individuals with type AB blood had an 83% higher risk of stroke. Furthermore, a protein known as Factor VIII, which plays a role in blood clotting, was determined to account for 60% of the association between type AB blood and stroke risk. The combination of A and B antigens as well as higher clotting factor levels may influence inflammation, vascular function, and the likelihood of blood clots, leading to a heightened stroke risk.
The evidence for blood type B and stroke is less consistent. According to a 2023 meta-analysis that examined 145,000 stroke cases and 2,000,000 controls, there is no significant association between blood type B and ischemic stroke. Other smaller studies have found mixed results, with only weak associations between blood type B and stroke risk..
If you have blood type O, the research is a bit more reassuring. Multiple studies have found that people with type O blood generally have a lower risk of developing blood clots and by extension, a lower risk of ischemic stroke. According to the 2022 study mentioned above, those with type O blood were 12% less likely to experience an early-onset stroke compared to those with other blood types. People with type O blood typically have lower levels of von Willebrand factor and factor VIII, both of which play a role in clotting. While this can lead to slower clotting in injuries, it also seems to provide some protection against unwanted clots in the arteries.
One of the more interesting findings from recent research is that the connection between blood type and stroke risk may be stronger in younger adults. The 2022 Neurology study found that the difference in stroke risk based on blood type was more pronounced in people under 60. This may be because in older adults, other factors, like high blood pressure, atrial fibrillation, and diabetes, play a more dominant role in stroke risk. In younger individuals, genetic and biological differences such as blood type may stand out more clearly.
