You may have heard about a new report describing a possible link between blood type and the risk of heart disease, which has a lot of people concerned. Some previous studies, involving relatively small populations of people, have suggested such a connection, but others have failed to confirm it. Now, in a study of over 90,000 participants followed for over 20 years, we appear to have something approaching an answer: There is a connection between blood type and heart disease–but it’s not something to worry about.
What the Connection Means
There are four major blood types: O is the most common, occurring in about 40 to 45 percent of people; A; B; and AB, which is the least common, found in 2 to 8 percent of people. The new study found that people with type O blood had the lowest risk of heart attack (fatal and nonfatal combined), and that people with AB blood had the highest risk, approximately 1.23 times higher than those with type O. People with type A or B blood fell in between these two extremes. An increase of 23 percent may sound significant, but here’s a simple way to put it into perspective: Among women, only 1 heart attack occurred for every 800 person-years (1 person-year is a statistical measure defined as 1 person at risk of developing a disease during 1 year) for those with type O blood, compared to once every 630 person-years for those with type AB blood. For men, the numbers were, respectively, 1 heart attack for every 300 person-years in men with type O blood, and 1 heart attack for every 180 person-years for people with type AB blood.
Not Proof of Cause and Effect
So there is a difference that can be measured statistically, but for any one individual the likelihood that blood type will determine his or her cardiovascular health over a lifetime is extremely small. Note, too, that this is just an association–not proof of cause and effect. No one knows why blood type should have any impact at all on your heart health, although there is some evidence that people with type O blood have lower levels of certain proteins that increase their blood’s capacity to clot, thus essentially rendering their blood “thinner” and less likely to cause an acute coronary artery blockage.
What You Can to Do Lower Your Risk of Heart Disease
The bottom line is: Don’t worry. The association between blood type and risk of heart disease isn’t cause for concern. You can’t change your blood type, but what you can do is focus on managing the cardiovascular risk factors that you can control–like eating a balanced diet, exercising regularly, and not smoking. Focus on these aspects of a healthy lifestyle and chances are you’ll live a long and healthy life (without having to worry about your blood type).