Now, it may point to something more deadly, too: Your blood type may help determine if you’re at risk of a heart attack, new research presented at Heart Failure 2017—4th World Congress on Acute Heart Failure suggests.
Researchers analysed data on more than 1,300,000 people from nine previous studies, and concluded that those with type A, type B, or type AB blood were 9 percent more likely to have a cardiovascular event—like a heart attack—than those with type O blood.
The exact mechanism behind the increased heart risk isn’t exactly clear. But one possibility may be because people with non type-O blood have greater concentrations of a blood clotting protein called von Willebrand factor, which can make the development of a blockage that causes a heart attack more likely, the researchers say in a press release.
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People with non-O blood also tend to have higher cholesterol and higher levels of inflammation.
More research is needed to clarify the links between blood type and heart risks—and to look at each blood type separately—but the researchers believe that blood type may eventually play a role in risk assessment for heart disease, along with traditional factors like cholesterol, age, and blood pressure.
This article originally appeared on Menshealth.com.