Blood type is a trait “written” in genes that determines which set of proteins (antigens) is on the surface of your red blood cells (red blood cells).
Antigens trigger an immune system response that recognizes and destroys foreign proteins that enter the body. At the same time, antibody proteins corresponding to certain antigens circulate in the blood plasma. Actually, a blood group is a complex of certain antigens and antibodies.
The most important and widely used blood group classification system in medical practice is the AB0 system. According to this system, two types of antigens, A and B, may be present or absent on the surface of red blood cells, and antibodies to them, anti-A and anti-B, may or may not circulate in the blood plasma, respectively.
Moreover, antigens and antibodies should not match, otherwise red blood cells will be destroyed.
Thus, there are four combinations (blood types): 0 or first, A or second, B or third, and AB or fourth.
- 0 (I) – there are no antigens A or B on the surface of red blood cells, but antibodies to them are present in the plasma;
- A (II) – antigen A is present on the surface of erythrocytes, and an antibody to antigen B is present in the plasma;
- B (III) – antigen B is present on the surface of erythrocytes, and an antibody to antigen A is present in the plasma;
- AB (IV) – antigens A and B are present on the surface of red blood cells, but there are no antibodies in the plasma.
All this is of cardinal importance during donor blood transfusion and donor organ transplantation – in case of incompatibility, antibodies cause a reaction of destruction and adhesion of blood cells, which seriously threatens the life of the recipient.
Another important blood group classification system is the Rh factor system. Like everything related to blood, this is a very complex system, but to simplify it, the Rh factor is a specific complex of antigens that may or may not be present on the surface of red blood cells. If it is present, the blood is considered Rh-positive (+), and if not, it is Rh-negative (-). The majority of the world’s population has Rh-positive blood, since this trait is dominant in inheritance.
In addition, hundreds of other antigens that may be present on blood cells and antibodies that may circulate in plasma have been identified. To date, 45 rare blood groups have been discovered, based on almost 400 different antigens and antibodies, and this number is constantly growing.
What can your ABO blood type say about your health?
Although there is no scientific evidence that blood type diets actually work, or that blood type affects character and destiny, the same cannot be said about predisposition to certain diseases. The results of some studies suggest that there is still some connection between blood type and health.
The biological basis of this connection cannot always be explained; there are no guarantees that you will or will not get sick from a particular disease, but knowledge about the possible risks can still be useful.
Cardiovascular diseases
Good news for people with blood type 0 (I) – compared to other groups, they have a significantly reduced risk of heart attacks, strokes, atherosclerosis, coronary heart disease, deep vein thrombosis and pulmonary embolism. Moreover, the maximum risk of these diseases is in people with the rarest blood group, AB (IV). In them, compared with group 0 (I), the risk is increased by 23%, in people with group B (III) – by 11%, and in people with group A (II) – by 5%.
This may be due to increased levels of a protein that promotes blood coagulation (thickening) and the formation of blood clots.
In particular, such results were shown by a study conducted by scientists from the School of Public Health at Harvard University, whose article was published in 2012 in the journal Arteriosclerosis, Thrombosis and Vascular Biology. An increased risk of heart attacks and strokes in people with blood types other than O (I) was also reported in a study presented at the 2017 World Congress on Acute Heart Failure.
Dementia
A study involving 30 thousand people, conducted by scientists from the University of Vermont (USA), showed that people with blood type AB (IV), compared with other groups, have an 82% increased risk of memory and thinking problems leading to dementia . This may be due to the predisposition of people with this blood type to vascular disorders.
Therefore, if you have blood type IV, it is especially important for you to lead a healthy lifestyle, monitor your blood pressure, stop smoking, eat right and exercise.
Stomach and pancreatic cancer
Another piece of good news for people with blood type 0 (I) is that compared to other groups, they have a significantly reduced risk of getting these two types of cancer. At the same time, the risk of stomach cancer is especially increased in people with blood type A (II), possibly because they are more likely to have the gastric bacterium Heliobacter pylori, which contributes to the development of ulcers and inflammation of the gastric mucosa. True, there is evidence that people with the first blood group have an increased risk of developing gastric and duodenal ulcers, which are also caused by the bacterium Heliobacter pylori, but, for some reason, this is less likely to lead to cancer.
In addition, as Norwegian scientists have found , people with blood groups A (II), B (III) and AB (IV) have an increased susceptibility to pancreatic cancer.
Malaria
Again, the good news for people with blood type 0 (I) is that they are protected from this infection because the causative agent of the disease, Plasmodium falciparum, has difficulty attaching to antigen-deprived red blood cells.
Diabetes mellitus type 2
There are suggestions that people with blood groups A (II) and B (III) have an increased chance of developing type 2 diabetes, but what this may be related to is still unclear.