Blood types
Blood group is determined by antigens on the red cell surface. The ABO system covers A, B, AB and O; the Rh system adds positive or negative depending on the D antigen. Transfusing incompatible blood causes the recipient’s antibodies to attack the donated cells, which can be fatal.
The numbers
- Universal red cell donor
- O negative
- Universal plasma donor
- AB
- Most common worldwide
- O positive
- Rarest of the eight
- AB negative
- Recognised blood group systems
- over 40
Worth knowing
Distribution varies enormously by population — type B is far more common in parts of Asia than in western Europe, and type O approaches 100% in some indigenous American populations. Beyond ABO and Rh there are more than forty recognised blood group systems; the Bombay phenotype is so rare that those who have it can generally only receive blood from other Bombay donors.
A common claim that is wrong
The blood type diet has no evidence behind it. A controlled study found the diets produced effects unrelated to the participants’ actual blood groups.
Structural reference only — this is not medical advice, and individual variation in every figure here is substantial. Anything concerning your own health belongs with a clinician rather than a reference page.
Common questions
- What does the blood types do?
- Blood group is determined by antigens on the red cell surface.
- Blood types — key numbers
- Universal red cell donor: O negative. Universal plasma donor: AB. Most common worldwide: O positive. Rarest of the eight: AB negative. Recognised blood group systems: over 40.
- Is it true that…
- The blood type diet has no evidence behind it. A controlled study found the diets produced effects unrelated to the participants’ actual blood groups.