The blood type diets
In the early 20th century, Austrian biologist Karl Landsteiner carried out research that would earn him the Nobel prize in 1930 and lead to the discovery of blood groups and their characteristics. These studies were subsequently perfected by Italian researchers Alfredo De Castello and Adriano Sturli, and German researchers Emil von Dungern and Ludwig Hirszfeld. Other researchers would later explore in depth the relationship between blood groups, nutrition and disease.
Almost at the same time, around 1960, the American naturopathic doctor James D’Adamo had begun to experiment on his patients with diets differentiated according to blood groups. His son Peter, himself a naturopath, continued and elaborated his father’s research, finding confirming instances that were later included in his books.
His theory hypothesizes that blood groups differentiated as a consequence of the different diets adopted by human groups in the course of evolution. D’Adamo conjectures that geographic isolation and nutritional practices gave rise to blood group differentiation by altering the various antigens found on the surface of red blood cells.
This in turn would result in individuals within a given blood group having an affinity for some foods and not for others. The fact that blood groups made their appearance at different moments in history and in different geographical areas lends credence to this theory, but there is as yet no scientific proof of its validity. D’Adamo’s work has surely drawn upon the existing contributions on this subject, and has explained the evolution of blood groups and their relationship with the diet, but I think it is important to examine this thesis in depth and to develop it further.
The variables to consider are many, and the link between diet and blood groups should not be taken as incontrovertible dogma. In fact, to think that every person in a given blood group could resort to the same diet constitutes rather a rigid schema that disregards the genetic differences that render each human being unique, even within the same blood group.
Blood groups are the most immediate and straightforward expression of our immunitary characteristics. Foods regarded as compatible with a certain blood group may not be so in practice; and foods regarded in theory as harmful may actually prove not to be so, though this happens rarely. It is not my intention to strike out from the diet every food that might cause unusual reactions, but to provide a simple method that would enable anyone to find an explanation for a number of signals that emerge when we stray from a healthy diet.