Published: 18 December, 2003

Most common blood type? O positive - positively

What is the most common type of blood?

It is important to remember that your blood is a complex mixture of substances and that each has an important function: Red blood cells (contain hemoglobin and help with oxygen transport), white blood cells (help fight infection), platelets (responsible for clotting), and plasma (the liquid portion which allows your blood to flow). For this question, let's take a closer look at the red blood cells.

Each red blood cell has attached to it some very small protein molecules called agglutinogens. There are three types of agglutinogens: A, B, and O. If you have only type A agglutinogens, then you will have "A" blood, if you have type B, then you will have "B" blood. Some people have both A and B and their blood is called "AB". There are many people (including myself!) who have no agglutinogens at all attached to their red blood cells … our blood type is called "O". Remember that just because we do not have these proteins that it does not make us any less healthy than our peers with other blood types!!

In addition to blood type (A, B, AB, and O), there is a small protein that some people have in their blood. Those who have it are said to be "Rh positive" an those who don't are "Rh negative".

According to the American Association of Blood Banks, the most popular type of blood in the U. S. is "O positive" with 38% of the population falling into this category. The least popular is "AB negative" with 1%. It is interesting to note, though, that the distribution of blood types varies according to geographic location and race. If you are interested in reading more about this, there is some interesting information at anthro.palomar.edu/vary/vary_3.htm.