The Blood Type That Increases Your Risk Of Stroke, According To Science

Do you know your blood type? Unless you regularly donate blood, you might not. Blood types are categorized by the presence of specific antigens and proteins, and you inherit this blood type from your parents. Although you might not think about your blood type often, a 2022 meta-analysis in Neurology found that your blood type might be linked to your risk of stroke.

The researchers pulled together the results of 48 studies to see how genetics are linked to an early-onset stroke (EOS). People with the A blood type are 16% more likely to have an EOS compared to people with other blood types. Blood type O is the most common, and people with this blood type have a 12% lower risk of EOS and late-onset strokes (LOS).

"We still don't know why blood type A would confer a higher risk, but it likely has something to do with blood-clotting factors like platelets and cells that line the blood vessels as well as other circulating proteins, all of which play a role in the development of blood clots," said study co-principal investigator Steven J. Kittner, MD, MPH, Professor of Neurology at the University of Maryland, in a news release. The researchers said that people with blood type A shouldn't be alarmed and seek additional screenings.

The researchers noted that previous research found people with blood types A, B, and AB are more likely to have certain health issues, such as blood-clotting disorders. Your blood type is determined by the ABO gene, and the A and B variants of this gene create enzymes that add sugars to a protein on the surface of your red blood cells. People with the O blood type produce a non-functional enzyme. People who have blood-clotting issues have these sugars on their blood cells, and those with the A blood type have higher levels of blood-clotting proteins. The ABO gene also influences the amount of proteins that produce inflammation, which also influences blood clots.

(Read about other ways your blood type can affect your health.)

The American Stroke Association says 87% of all strokes are ischemic strokes, which are linked to blood clots blocking the flow of blood to the brain (here are symptoms of a stroke you shouldn't ignore). While strokes are more commonly associated with older adults, up to 15% of strokes occur in people younger than 45, according to Sutter Health. While you can't control your blood type and genes, you can decrease your risk of stroke by managing your weight, exercising, eating a healthy diet, and quitting smoking.