Ask Dr. D'Adamo

Blood Type: My Take On The Japanese

The first reference I could find linking blood type to personality in Japan was written in 1927. It appeared to be a study of the psychological attributes of Japanese schoolchildren. But as with the Japanese, nothing is ever simple! Not only did the study show that Type A children had higher IQs, it also managed to prove that Type B children defecate more than others! This is my problem with most of the Japanese research into blood types; it tends to be a hodgepodge of some science, some pop psychology, and a whole lot of baloney. Whereas I now think the Japanese did have some valid starting points with regards to blood type and personality, they tended to look at personality as an almost robotic-like concept, which most people find reprehensible. There is much more free choice involved in the type of person you are, than would be programmed by your blood type.

What is more interesting to me is not how people will function while they're healthy, but rather how the neurochemistry of a person will function under stressful circumstances. In a state of mental or physical stress, a person will tend to fall more into type. For example, we talked about the fact that Type A tends to secrete larger amounts of cortisol under stress -- this has been reported in several studies. High levels of cortisol have bad effects on the immune system. Perhaps this explains the statistically significant difference between Type A and the other types with regards to the rates of cancer.

Curiously, several studies from Australia also proved that Type A tends to have thicker blood when under stress than the other blood types, which may help account for their higher rates of heart disease. With Type O, the name of the game is dopamine, which is, believe it or not, a chemical, the control of which is regulated by a gene that sits virtually right underneath the gene for ABO blood type. With Type B, another gene close to the ABO blood type gene regulates the metabolism of nitrous oxide, which research shows is involved in the mind-body connection.

A lot of this neurochemical response to stress that is different from one type to another has nothing to do with the physical expression of blood type. It has rather to do with the genetic expression of blood type. This is probably why so many health professionals scoff at the notion of blood type regulating anything. They can only harken back to what they were taught about the physiology of blood type, but do not have knowledge that it controls a wide range of genetic information.