Not all blood types may be alike when it comes to heart disease risk.
Harvard researchers found certain blood types seem to be associated with a higher risk of coronary heart disease than others. Specifically, people with type AB -- only about 7 percent of the U.S. population -- have a 23 percent increased risk of the condition, compared with type Os.
Meanwhile, people with type B blood had an 11 percent higher risk of coronary heart disease, and people with type A blood had a 5 percent higher risk compared with people with type O blood, according to the Arteriosclerosis, Thrombosis and Vascular Biology study.
The researchers noted that about 43 percent of people in the U.S have Type O blood.
"While people cannot change their blood type, our findings may help physicians better understand who is at risk for developing heart disease," study researcher Dr. Lu Qi, M.D., Ph.D., an assistant professor in the Department of Nutrition at the Harvard School of Public Health, said in a statement.
"It's good to know your blood type the same way you should know your cholesterol or blood pressure numbers," Qi added in the statement. "If you know you're at higher risk, you can reduce the risk by adopting a healthier lifestyle, such as eating right, exercising and not smoking."
The study included blood type analysis from nearly 100,000 people between ages 30 and 75, who participated in the Nurses' Health Study and the Health Professionals Follow-Up Study, in which they were followed for at least 20 years.
The researchers said they have yet to understand the exact cause for this blood type-heart disease connection. But, they did say that past research has suggested a link between having A type blood and higher levels of "bad" LDL cholesterol, and a link between having AB type blood and inflammation.
Last year, a study presented at the conference of the American Heart Association suggested a link between blood type and stroke risk, too. That study showed that AB type blood in men and women, and B type blood in women, is linked with an increased risk of stroke, compared with people with O type blood, the Associated Press reported.
That study was conducted by researchers from the Brigham and Women's Hospital, and included health data from 90,000 people.