The Blood Type Diet and Peter D'Adamo

18 March 2002

“Your blood type is the key that unlocks the door to the mysteries of health, disease, longevity, physical vitality, and emotional strength. Your blood type determines your susceptibility to illness, which foods you should eat, and how you should exercise. It is a factor in your energy levels, in the efficiency with which your ‘burn’ calories, in your emotional response to stress, and perhaps even in your personality.”

from Eat Right for Your Type by Peter D’Adamo



There’s an appealing symmetry to American naturopath Peter D’Adamo’s “blood type diet”, which probably goes a long way to explaining why it has become one of the world’s most popular.

Long ago in the palaeolithic era, D’Adamo says, hunter-gatherer humans had type O blood, and ate diets high in fat and protein. When their populations grew too large - beginning about 25,000 years ago - they developed agriculture.

In response to this radically new lifestyle came type A blood - which was more resistant to the infectious diseases brought by crowded settlement. Type B blood appeared when these humans migrated out of Africa to other parts of the world. Then when populations burgeoned again and the races mingled, type AB materialised.

Thus, the theory goes, the appearance of of the four blood types  in the “ABO” system accompanied the major stages of human development. But because we no longer eat according to the demands of our blood type, the “dangerous glue” of dietary lectins [proteins] from blood type-incompatible foods afflict our systems and cause disease.

D’Adamo’s book is the recipe for correcting these mistakes. It is replete with statements like: “Type As can’t digest tomato or vinegar” - though generally the statements aren’t supported by scientific references.

D’Adamo’s diet has generated an entire industry. Eat Right for Your Type sold over a million copies and was translated into 40 languages. From D’Adamo’s website you can purchase food, drinks and supplements specific to your blood type, blood-typing kits, videos - and D’Adamo’s new book, Live Right for Your Type. It tells how you can tailor your daily schedule, sleep, stress and emotions to your blood type.

So - is there any science behind these encompassing theories?

Well, key to the diet’s validity is the notion that we developed blood types specific to major human eras. Anthropologist Ruediger Hoeflechner tackled this proposition during an online scientific colloquium on early human diet - the “palaeodiet symposium”:

“The idea that O is the original blood group of hunter-gatherers and blood types A and B came up later in history is entirely antiquated. It can be traced back to [1919]. Today we know that A and B antigens are present...in many other primate species, including chimpanzees, gorillas, orangutans, gibbons and macaques.”

Hoeflechner added that “phylogenetic [developmental history] analysis suggests that the human A and B alleles [gene forms] are at least a few million years old. Sorry, Mr D'Adamo: blood groups A and B are as palaeolithic as blood group O. They are ancient, not adaptations to [agriculture-created] dietary changes, and can also be found in most recent hunter-gatherer societies.”

Peter D’Adamo did not respond to questions from The Age. However on his website, D’Adamo rejects Hoeflechner’s criticisms, stating that ABO genes are found in different “gene loci”, or places on the chromosome, in different species. This means that “their association with digestive secretions (in humans) and hence their use in determining diet strategies...are not capable of being extrapolated out to other species.”

D’Adamo added: “Numerous studies have shown that type O predominates in very high percentages in populations thought to be "ancient" and "isolated" so as to not have received any infusions of A and B genes. This is true to this day of the native Americans and Basques, whose percentage of type O approaches or exceeds 90%.”

Colorado State University’s Professor Loren Cordain, the world’s foremost authority on human evolutionary diet, told The Age:

“Recent mitochondrial [maternal] DNA analyses of European population have shown that all 650 million living Europeans arose from one of seven founding hunter-gatherer tribes. Surprisingly, the Basque people do not have an ancient lineage, but rather an origin date - about 17,000 years ago - that is similar to three of the other European founding populations, but considerably younger than [others]. If D'Adamo's hypothesis were true, then the relative percentage of type O blood groups should also be similarly high in other founding European populations.”

Cordain adds: “Because the spread of agriculture from the Near East to Europe is now known to not have occurred in a demic fashion - the spread of people rather than of technology - the diversity of blood types in Europe could not have been evolutionarily selected on the sole basis of the spread of agriculture and the availability of Neolithic [agricultural] foods.”

Cordain points out that because the Agricultural Revolution is only 500 generations old at best, “the world-wide mixture of ABO blood types would not have had sufficient time to achieve its current distribution” under D’Adamo’s hypothesis.

Finally, Cordain states that there are many antigens [substances capable of inducing formation of antibodies] present on red blood cells in addition to “A” and “B” antigens. The choice of the A and B antigens to type blood was to some extent arbitrary: other antigens have often been employed instead.

So “because of the enormous variety of cell surface antigens,” Cordain says, “it seems unlikely that selective pressure based upon elements in the diet would have solely influenced the A and B antigens.”

US nutritional scientist Vinny Pinto conducted some experiments on himself to test D’Adamo’s recommendations:

“In two separate tests using urine Indican testing, I was able to demonstrate that although I was daily eating large quantities of foods which are not, according to D'Adamo's book, suitable for my blood type, I showed no trace of urinary indoles [excretions] - which would indicate undesirable fermentation in the lower gastro-intestinal tract - as repeatedly and strongly predicted by Dr Peter D'Adamo in his book.”

Internationally-known Australian nutrition researcher, Professor Jennie Brand-Miller of Sydney University, states:

“The blood type diet has absolutely no scientific credibility.  There is nothing published in the medical literature to back up anything the book says.”

Staffan Lindberg (MD, PhD), a scholar of evolutionary nutrition at Lund University in Sweden, told The Age:

“The blood type diet is very dubious indeed. But,” he acknowledges, “the possible health risk of dietary lectins such as wheat lectin is very intriguing. [But] it also seems very obvious that the negative health consequences of dairy products and cereals and the benefits of meat apply in a rather similar manner for all ethnic groups on the planet. There are some differences, but as a whole these are rather small.”

Depending on your blood group, the blood type diet prescribes more - or less - of such foods as grains, meat or dairy. It also prescribes organic foods, which are higher in nutrients and devoid of poisons. So the laws of chance dictate that it will work for some people.

And D’Adamo counsels againt junk foods based in sugar, “bad” fats and salt - which is going to do anyone a power of good.

In a nutshell, it seems likely that the blood type diet “works” for some people - but it’s unlikely to have anything to do with their blood type.