Research conducted at Harvard University shows people who have A, B or AB have a slightly higher risk of heart disease compared to those who are blood type 0, which is the most common.
Researchers studied nearly 90,000 people over several decades. The results showed people with type AB blood had a 20-percent higher risk of developing heart disease than people with type O blood.
Negative or positive blood did not have any affect on heart disease risk.
A doctor not involved in the study points out that the increase was modest and other factors including smoking have a bigger impact on the risk of heart disease.
The study is published by the American Heart Association.
