Blood Types Linked to Heart Disease in Unscientific Science Study

People from blood groups A, B, and AB are at greater risk of heart disease than those with type O, a new study finds. Or does it?

People from blood groups A, B, and AB are at greater risk of heart disease than those with type O, a new study finds. Or does it?

BBC (“Blood group ‘linked to heart disease’“):

People from blood groups A, B and AB are more at risk of heart disease than those with the more common blood type O, a study suggests.

Those with the rarest blood group, AB, are the most vulnerable – they are 23% more likely to suffer from heart disease than those with blood group O.

The researchers do not know why this is, but are now looking at how blood groups respond to improved lifestyle.

The findings are published in an American Heart Association Journal.

The study also found that for individuals with blood group B the risk of heart disease increased by 11%, and for blood type A, by 5%.

Lead author Prof Lu Qi, from the Harvard School of Public Health in Boston, said: “While people cannot change their blood type, our findings may help physicians better understand who is at risk of developing heart disease.

“It’s good to know your blood type the same way you should know your cholesterol or blood pressure numbers.

Reduce the risk
“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.”

This is good advice. Thankfully, I’m an O-, so I can continue my gluttonous ways.

The British Heart Foundation stressed it is important that we all look after ourselves to reduce the risk.


At any rate, one presumes they’ve done some basic multi-variate analysis here and ruled out blood type/group being a proxy for race, ethnicity, and lifestyle.

The study did not look at why different blood types appear to have different risks of heart disease.

Prof Qi said: “Blood type is very complicated, so there could be multiple mechanisms at play.”


The findings are based on two large US analytical studies – 62,073 women from the Nurses’ Health Study and 27,428 adults from the Health Professionals Follow-up Study. They were between the ages of 30 and 75 and followed for 20 years.

As this study group was predominantly Caucasian, the researchers say it is not clear if their findings would be reflected in other ethnic groups.

The work is published in Arteriosclerosis, Thrombosis and Vascular Biology, an American Heart Association journal.

The team is now looking at whether people with different blood groups respond differently to changes in lifestyle, such as diet, exercise, cholesterol intake.

So . . . we actually don’t know anything useful?

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James Joyner
About James Joyner
James Joyner is Professor and Department Head of Security Studies at Marine Corps University's Command and Staff College. He's a former Army officer and Desert Storm veteran. Views expressed here are his own. Follow James on Twitter @DrJJoyner.


  1. Rick Almeida says:

    You’re right, James – this doesn’t seem like a very robust study, at least from the sense of establishing causation.

    That said, if I remember my biology, blood type is a pretty straightforward genetic combination, and I’m not sure should serve as a proxy for anything, particularly lifestyle…blood type is set at conception (fertilization?).

  2. Dave Schuler says:

    A couple of things. First, in ethnically very homogeneous Japan the prevalence of blood types, according to the Japanese Red Cross is A+ 39.8%, B+ 19.9%, AB+ 9.9%, and O+ 29.9%, with smaller percentages of other types. That’s similar to the somewhat less ethnically homogeneous Hungary, the even less ethnically homogeneous France, and the very diverse United States. Said another way blood types are known not to be proxies for race and ethnicity already.

    The possible exceptions to this is that it is believed that B blood types were unknown in the Americas or Australia before the arrival of people from Europe, Asia, and Africa in the historic period.

    And, yes, I agree that it would be helpful if the study attempted to isolate factors like age and lifestyle.

    However, that being said I welcome this study and the likely follow-ups. Blood types and who knows what other genetically-determined factors may be significant factors in heart disease. We really don’t know because it hasn’t been studied enough.

    One of the reasons that it hasn’t been studied enough is that so many broad, sweeping, racist, and bogus claims about blood type and its relation to personality, behavior, etc. were made in the early decades of the last century.

    I’m B+ by the way and my family has little or no history of heart disease.

  3. OzarkHillbilly says:

    Dave, am I reading this right?

    A pos 39.8%, B pos 19.9%, AB pos 9.9%, and O pos 29.9%, which adds up to 99.5%?

    If so, Wow. I am A neg, and knew it was the 2nd rarest(?) blood type (AB neg being the rarest) but had no idea of just how rare that might be.

  4. Dave Schuler says:


    That’s in Japan. They say .2% A- there. The distribution is slightly different in Western Europe.

  5. MarkedMan says:

    James, I don’t think this is an ‘un-scientific’ study. There’s nothing here that shows the data wasn’t gathered correctly or that there are errors in it. It may, or may not, be over interpreted, but that isn’t the studies fault.

  6. At any rate, one presumes they’ve done some basic multi-variate analysis here and ruled out blood type/group being a proxy for race, ethnicity, and lifestyle.

    No need, when the claim is one of simple correlation. If blood type correlates with heart disease, then that can be reported without risk of contradiction.

    If the claim was that “blood type matters most” or something stupid like that, then they’d have to prove that, but they made no such claim.

    Also, understand that the purpose of the study was not to generate general press responses nor to make any O-types slack off. The main thing scientists are going to take away is that something is going on with blood type:

    While those with blood group O may benefit from increased levels of a chemical which helps blood flow and clotting.

    Looking for that chemical would help us all, O-type or not.

  7. @MarkedMan:

    The general press can read science unscientifically, film at 11

  8. OzarkHillbilly says:

    @Dave Schuler: Thanx. I say again, Wow. I suddenly feel like an endangered species.

  9. Dave Schuler says:

    You use a monicker of “OzarkHillbilly” and now you feel like an endangered species? 😉

  10. al-Ameda says:

    the American Red Cross has data on the distribution, by blood type in America.

  11. Elisha says:

    Did they even consider the RH-factors in their studies? It’s interesting that it seems that they decided to group both the RH-Pos. blood with the RH-Neg blood. Neg’s have a different protein and our blood does not work the same. The Rh factor is a type of protein on the surface of RBC’s. Most people who have the Rh factor are Rh-positive. Those who do not have the Rh factor are Rh-negative. We are prone to autoimmune diseases more than those, with positive blood and an obvious fact to point out is that the pregnant female’s RH-Neg. blood can attack it’s RH-Pos. fetus. That seems like an autoimmune scenario to me. I wish that Harvard and others in the medical world would stop lumping negative blood types with the positive blood types finally start researching RH-Neg blood and it’s association with autoimmune diseases, heart disease, and all other conditions. It’s ironic to me that Qi stated, “If we found risk factors would cause a different response in people with different blood types, we can provide specific recommendations for people with different blood types.” At this point, there is few studies such as this one, that speaks to the negatives of the world. Why not study it’s connections to specific diseases and provide us with specific recommendations? There are numerous groups and forums of people, who have negative blood-type and are experiencing a myriad of autoimmune symptoms or have been diagnosed with an autoimmune disease. So far, doctors look at me with a strange face when I raise the topic of negative blood and autoimmune conditions. By the way, I was just diagnosed with Hashimotos TODAY and it is an autoimmune disease of the thyroid. Many professionals have noted that red heads are more at risk for thyroid conditions. Red hair is also prevalent among negative blood. This is not a coincidence. 🙂