Do you know your blood type? There’s a good chance that you don’t. More Americans know their horoscope sign (66 percent) than their blood type (51 percent), according to a survey published last year by laboratory company Quest. There are compelling health reasons why you should know, especially when it comes to your heart. Research suggests that people with certain blood types — namely A and B — are at higher risk to develop blood clots and to have heart attacks and strokes.
“We think about blood type a lot when we think about transfusions,” says Robert Salazar, M.D., a cardiologist at Memorial Hermann Health System in Houston. There may be some benefits to know about it for heart health, he adds. “Increasingly, there is a push towards the individualization of medicine and medical advice,” he explains. Adding information about blood type, he says, may help inform doctors on how to best treat patients.
Types of blood
Blood types are determined by the presence or absence of certain substances, called antigens, that can trigger an immune response if they are foreign to the body.
There are four main blood types: A, B, O and AB, according to the American Red Cross. In addition to these antigens, there’s a protein called the Rh factor, which can either be present (+) or absent (-). That means there are eight blood subtypes: A+, A-, B+, B-, O+, O-, AB+, AB-.
Types A and B and blood clots
People with blood types A and B are at higher risk to develop blood clotscompared with people who have type O blood, according to a 2020 study published in the American Heart Association journal Arteriosclerosis, Thrombosis, and Vascular Biology. The study, which looked at more than 400,000 people, found that types A and B were 50 percent more likely to develop blood clots in the legs called deep vein thrombosis and 47 percent more likely to develop a pulmonary embolism — when a clot travels to the lungs — than people with type O blood. They were 8 percent more likely to have a heart attack and 10 percent more likely to experience heart failure than type Os.
Why blood type affects clot risk
There are many possible reasons for why this happens, says Mary Cushman, M.D., a hematologist at the University of Vermont Medical Center and a professor of medicine and pathology at the Larner College of Medicine at UVM in Burlington, Vermont.
“The enzyme that controls blood type has other actions,” she explains. One of these is to modify a protein called von Willebrand factor, which is very important in forming blood clots. “The modifications to the protein are different in different blood types,” she says. “So people with type O blood have the lowest levels of von Willebrand factor on average and the lowest risk of abnormal clots. Type AB has the highest level and, in some studies, the highest risk of blood clots.”
There may also be some differences in platelets, the small cell fragments in the blood that form clots, says Joshua Beckman, a cardiologist at the UT Southwestern Medical Center. This may make you more susceptible to clotting.
To learn more about what your blood type can mean for your health, from AARP, CLICK HERE.
