Is Eating Right For Your Blood Type A Sham?
Author: Dr. Stephen Chaney
Does the Blood Type Diet really work? In 1997 Dr. Peter J. D’Adamo wrote a book about the blood type diet called “Eat Right 4 Your Type”. Dr. D’Adamo claims that people with different blood types process food differently, so their blood type determines the type of diet that is healthiest for them. Specifically, he claims that people with:
- Blood group O are descended from hunters and should consume high protein diets.
- Blood group A are descended from farmers and should consume a near vegetarian diet – completely avoiding red meats.
- Blood group B are descended from nomads. They have the most flexible digestive system and can eat the widest variety of foods – even dairy products, which he does not recommend for any of the other blood types.
- Blood group AB are an enigma and are somewhere between blood group A and blood group B.
It’s an interesting concept. Dietary recommendations are made for populations as a whole, and there is tremendous genetic variation in populations. Because of that genetic variation, there is no perfect diet for everyone. Every knowledgeable health expert will tell you that.
The question then becomes “How do you know what kind of diet is healthiest for you?”
The blood type diet is a very simple system. Your blood type is easy to determine. Once you know your blood type you know what to eat. There’s no guesswork.
Could it really be so simple? Over 7 million copies of Dr. D’Adamo’s book have been sold. Millions of people believe in this concept. So it is only fitting to ask “What is the evidence?”
An Objective Scientific Analysis of the Blood Type Diet
There is no doubt that blood type is related to some human genetic and physical traits, but the important question is whether blood type is related to the health outcomes of different diets – the central thesis of Dr. D’Adamo’s book. A Belgian group lead by Dr. Emmey De Buch did a systematic search of the scientific literature to answer that very question (L. Cusack et al, Am J. Clin. Nutr. , 98: 99-104, 2013).
They identified 1415 scientific articles that had the phrase “blood type diet” in either the title or abstract. Then they begin the elimination process. They eliminated:
- Studies done in test tubes, cell culture, or animals. Only human clinical studies were included.
- Reviews, commentaries, letters or opinions. Those contained no original scientific research.
At this point they were down to just 16 published clinical studies. Then they asked which of those studies were designed to test the central hypothesis of the blood type diet. They asked:
- Did the study start with human subjects grouped according to blood type?
- Did the study have an intervention in which the subjects were required to adhere to a particular type of diet?
- Did the study measure a health outcome of the dietary intervention?
Guess what? Only one study met these criteria. Just one! And it was a fairly weak study involving a totally different blood typing system than the ABO blood groups.
The Bottom Line:
1) There is no scientific evidence supporting the blood group diet. A lot has been written about the diet, but nobody has actually shown that it works. The Emperor Has No Clothes!
These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.