Blood Type: What Does It Really Affect?

October 28, 2025

2 min read

Some people use blood type to choose their diet, others try to determine character traits, and others look for a predisposition to the disease. The question is: does blood type affect human health and behavior?

Key takeaways

Some people use blood type to choose their diet, others try to determine character traits, and others look for a predisposition to the disease.
What are blood types?
Truths and myths

Who this is for

People exploring Blood through blood, tests.

Why it matters

This piece helps you get oriented quickly, then move into a collection or series if you want to keep going.

Article author

Dr. Ely

General practitioner

What are blood types?

In 1901, while studying the process of blood coagulation of different people when mixed, the Austrian-American physician and scientist Karl Landsteiner concluded that there are different blood types.

Later he created a system with four blood groups: 0, A, B, and AB. The letters are the types of antigens on the surface of red blood cells (erythrocytes). Antigens are special substances that the body's immune system reacts to. Different people have different antigen sets, so only a compatible blood type can be used for transfusion.

44 percent of people are blood O, 42 percent are blood type A, 10 percent blood type B, and 4 percent are blood type AB.

Truths and myths

Many theories attribute certain characteristics to people with different blood types. But none of them have a sufficient scientific basis.

For example, in the middle of the 20th century, British and Swedish scientists conducted large-scale studies and determined that a set of red blood cells can provide information about a person's predisposition to certain diseases:

O blood type people are more prone to gastritis, peptic ulcers, kidney stones, and lung problems (chronic bronchitis, tuberculosis, bronchial asthma).
A blood type people are more susceptible to stomach cancer, leukemia, chronic cholecystitis, cholelithiasis, thrombosis, and miscarriages.
B and AB blood types are more likely than others to face pancreas cancer, ovarian cancer and infections of the genitourinary system, cardiovascular diseases, neuroses, and Alzheimer's disease.

According to Japanese scientists, many people with B type blood group live longer than others. And O blood type people are bitten by mosquitoes twice as much as people in any other group.

American scientists have found that O blood type people are least at risk of contracting the SARS-COV-2 virus. And A blood type people suffer a lot from the disease since they have an increased concentration of von Willebrand factor in the blood, which triggers the process of thrombus formation.

Diet by blood type

One notable story related to blood groups is the diet of the American naturopath Peter D'Adamo. He stated that blood type affects the body's ability to digest different types of food and recommended eliminating foods from the diet that are "unsuitable to blood."

The only trick was that, among other things, all patients were forbidden to eat processed food, all kinds of fast food, and simple carbohydrates — no wonder they started to lose weight. Some studies carried out by scientists around the world have proven that the blood type diet works solely by limiting harmful foods in the diet. No miracles involved!

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