Blood Type May Affect Stroke Risk

Blood type might have an impact on a person’s risk of stroke, a new study suggests. People with O blood, the most common type, had the lowest risk. People with AB blood, the least common type, had the highest risk. They were 26% more likely to have a stroke than people with O blood. The study was based on medical records for 90,000 men and women. All were involved in health studies that have kept track of people for more than 20 years. Stroke risk also was higher in people with B blood, but only among women. They were 15% more likely to have a stroke than women with O blood. Blood type is determined by proteins on the surface of red blood cells. These proteins affect immune system responses. Researchers said some blood types might make red cells more likely to clump together and cause clots. Type O, on the other hand, has been linked to an increased risk of bleeding.