Wednesday, December 15, 2010

The Blood Type Diet: A Critical Perspective

01/20/14 UPDATE:   On January 15, 2014 Wang et al published an empirical test of the central claim of the blood type diet hypothesis, i.e. that each blood type benefit more from one particular diet than others.  Confirming what I wrote in this post in 2010, Wang et al concluded: "Adherence to certain ‘Blood-Type’ diets is associated with favorable effects on some cardiometabolic risk factors, but these associations were independent of an individual's ABO genotype, so the findings do not support the ‘Blood-Type’ diet hypothesis." Read the full text in PLOS One.  Read my blog about the study here.

Thanks to Peter J. D’Adamo, N.D. , author of the book Eat Right 4 Your Type, many people believe that blood type determines your dietary requirements and that only people with O-type blood should eat a paleo/primal diet.  

In this post I will discuss all the errors in this blood type hypothesis. 
The Blood Type Diet Hypothesis

D’Adamo’s hypothesis can be distilled down to four main claims and a conclusion drawn from these claims.

Claim A: Evolutionary adaptation to diet patterns resulted in the ABO blood groups, so each of the four types is adapted to a different type of diet and set of foods.
Claim B: People of different blood types have different antibodies in their blood and each blood type has a different susceptibility to diseases.
Claim C: Foods contain lectins that mimic blood group antigens and selectively cause blood agglutination (i.e. each food affects each blood group differently), and this causes diseases.
Claim D: Exposure to foods containing lectins incompatible with your blood type will cause agglutination of your blood which will cause diseases. As D’Adamo puts it, the lectins “target  an organ or bodily system and begin to agglutinate blood cells in that area.”

Conclusion: Therefore, people require diets tailored to their blood types, eliminating foods that have harmful lectins for their blood type.

The Four Diets

Blood type O

According to D’Adamo,  O-type blood is the “Original” blood type which evolved when humans lived by hunting supplemented by gathering.  He says these people should base their diets on lean meat and fish, supplemented with a selection of fruits and vegetables he deems suitable for this blood type.  O-types should avoid or greatly minimize dairy products and minimize or avoid grains and beans, particularly wheat.  According to D’Adamo, people with O-type don’t tolerate wheat “at all” yet he also says that they can eat sprouted wheat products (?).

Blood type A

D’Adamo claims that A-type blood arose as an adaptation to agriculture; conveniently, A is for agriculture.  He claims that this type can eat grains (except wheat), beans, most seafoods, many vegetables and  fruits, but should avoid dairy, meat, wheat, kidney beans, and lima beans.  He states that only people with A-type blood can and should eat a vegetarian diet.
Blood type B

D’Adamo refers to B-type as  “The Nomad.”  He implies that this type arose as an adaptation to pastoral lifestyles based on use of dairy products and meat from domesticated animals.  He states that B-types are adapted to a “balanced omnivore” diet that meat (but no chicken), eggs, dairy, beans, fruits, vegetables.  He advises people having the B blood type to avoid chicken, corn, lentils, peanuts, sesame, buckwheat, and wheat.

Blood type AB

D’Adamo calls type AB blood “The Enigma” and states that people having this blood type are adapted to a “mixed diet in moderation.   He advises that they can safely eat lamb, mutton, rabbit, turkey, pheasant, most seafood, dairy, beans, grains,             fruits,             and vegetables, but should avoid beef, chicken, kidney beans, lima beans, seeds, corn, buckwheat.

Basic Errors

As someone basing his whole approach to diet on blood types, D’Adamo appears disturbingly ignorant of basic facts about the evolution of the ABO types.

First, he claims that the O-type is the original blood type. He published his book in 1994, but by 1990 molecular biologists had determined that A-type is the original blood type.   In “Evolution of Primate ABO Blood Type Genes and Their Homologous Genes [full text available free],” Saitou and Yamamoto state [p. 405]:

“..the common ancestral gene for the hominoid and Old World monkey ABO blood
group is A type, and three B alleles evolved independently on the human, gorilla, and baboon lineages.”

The fact that both A-type and B-type antedate O-type seems predictable from the fact that O-type blood carries antibodies to A-type and B-type blood; for this to happen, O-type blood had to have emerged in an environment in which A-type and B-type antigens (the markers on A- and B- type blood cells) already existed. 

D’Adamo suggests that the blood types arose in humans as adaptations to dietary variations, implying that they are unique to humans.  In fact, ABO blood types occur not only in humans, but also in other primates.  Again, according to Table 5 in Saitou and Yamamoto, which presents data dating to 1964, more than 30 years before D’Adamo published his books:
·      The A phenotype occurs in chimps, orangutans, gibbons, baboons, Java macaques, sulawesi crested macaques, and squirrel monkeys (7 speicies).
·      The B phenotype occurs in gorillas, orangutans, gibbons, baboons, Rehsus macaques, pigtailed macaques, Java macaques, sulawesi crested macaques, and cebus monkeys (9 species).
·      The AB phenotype occurs in oragutans, gibbons, baboons, and Java macaques (4 species).
·      The O phenotype occurs in chimps, Java macaques, squirrel monkeys, and cebus monkeys (4 species).

Since none of these primates have ever practiced agriculture or domesticated dairy animals, it is clear that the A allele did not evolve as an adaptation to agriculture nor did the B allele emerge as an adaptation to consumption of dairy products. 

As noted above, the B-type has been found in the largest selection of species (9), followed by the A-type (7), and both O- and AB- type occur in the smallest selections (4 species each).  According to Saitou and Yamamoto, among this list of primates checked for ABO blood type, A phenotype occurred in 191 individuals, B in 75 individuals, AB in 44 individuals, and O in 20 individuals. 

According to Saitou and Yamamoto “It seems that the time of gene dupulication producing ABO and GAL genes may be around the emergence of vertebrates (ca. 500 MYA).”  [p.408]  In other words, these blood types have a much longer history than human dietary variations. 

Human Data

Its possible that D’Adamo did not mean to imply that the blood types arose only in humans.  Perhaps he meant that human adoption of hunting lifestyle selected for O-type, agriculture for A-type, and pastoralism for B-type.  In this case, we should find a predominance of O-type among all ethnic groups with a long history of living by hunting, especially those eating little plant food; a predominance of A-type among  ethnic groups having the longest histories of practicing agriculture; and a predominance of B-type among ethnic groups with long histories of pastoralism.

Unfortunately, the available data does not support this either.  So far as we know, Eskimos have never practiced agriculture or animal husbandry, and have long lived primarily by hunting, a diet enforced by their environment.  D’Adamo’s hypothesis would predict that Eskimos would have predominantly O-type blood.  According to, this is true of Greenland Eskimos (54% O, 36% A), but not of Alaskan Eskimos (38% O, 44% A), who have more A-type than O-type individuals, contradicting D'Adamo's hypothesis.

According to Wikipedia and, people of the Blackfoot or Niits√≠tapi tribe traditionally lived primarily on buffalo meat; classic hunters.  From Wikipedia:

“While the Niitsitapi were in the Great Plains, they came to depend on the buffalo (American bison) as their main source of food. The bison are the largest mammals in North America and stand about 6 ½ feet tall and weigh up to 2,200 pounds.[6] Before the introduction of horses, the Niitsitapi had to devise ways of sneaking up close to the buffalo without the animals' noticing so they could get in range for a good shot. The first and most common way for them to hunt the buffalo was using the buffalo jump. The hunters would round up the buffalo into V-shaped pens and drive them over a cliff (they hunted prong-horned antelopes in the same way). After the buffalo went over the cliff, the Indians would go to the bottom and take as much meat as they needed and could carry back to camp. They also used camouflage for hunting.[6] The hunters would take buffalo skins from previous hunting trips and drape them over their bodies to blend in and mask their scent. By subtle moves, the hunters could get close to the herd. When close enough, the hunters would shoot the bison with arrows, or use lances and spears to bring them down.

They used virtually all parts of the body and skin. They prepared the meat for food: by boiling, roasting and drying for jerky. This prepared it to last a long time without spoiling, and they depended on bison meat to get through the winters.[7] The winters were long, harsh, and cold due to the lack of trees in the Plains, so the people stockpiled the meat when they had the chance.[8] The hunters often ate the bison heart minutes after the kill, as part of their hunting ritual. The skins were prepared and used to cover the tepee. The tepee was made of log poles with the skin draped over it. It remained warm in the winter and cool in the summer, and a great shield against the wind.[9] With further preparation of tanning and softening, the women made special clothing from the skins: robes and moccasins. They rendered bison fat to make soap. Both men and women made utensils, sewing needles and tools from the bones, using tendon for fastening and binding. The stomach and bladder were cleaned and prepared for use as containers for storing liquids. Dried bison dung was fuel for fires. the fires. The Niitsitapi used almost every part of the buffalo and considered it a sacred animal, integral to their lives.[10]”

From this D’Adamo would predict that they had primarily O-type blood.  Wrong again. states that 82% of Blackfoot people have A-type blood, and only 17% have O-type. 

Looking from the other side, D’Adamo’s hypothesis would predict that Cantonese Chinese would have a higher incidence of A-type and lower incidence of O-type because they have lived for millennia on a rice-based agricultural diet. states that Cantonese Chinese have 46% O- and 23% A- types, the reverse of the D’Adamo prediction. 

Meanwhile, the northern Chinese (Peking) have 29% O, 27% A, and 32% B, a distribution which according to D’Adamo’s hypothesis would predict that the population has a long history of living on dairy products.  Unfortunately for D’Adamo, the pastoral lifestyle is not common in China at all, only practiced by Chinese in the western, mountainous provinces.

Just as one black swan is sufficient to disprove the claim that all swans are white, these few counter examples are sufficient to disprove the claims that hunting-based subsistence favors the O-type blood, while an agricultural subsistence favors the A type blood.  D’Adamo is just wrong when he asserts that dietary differences drive differences in distribution of blood types among humans. 

No Anatomical Evidence

All humans, regardless of blood type, cultural background, or  diet histories have the same basic gut design, dentition (number and type of teeth, type of enamel), type of saliva and digestive enzymes.  This is why we call them humans.  

For example, scientists have found no nutritionally relevant anatomical, physiological, or biochemical differences between Chinese and Eskimos. 

Nor are there any such differences between people with A-type and O-type blood.  

Medical Evidence?

D’Adamo claims that O-type people get ulcers more frequently than people with A-type because O-type individuals, according to him, produce more stomach acid than people with A-type blood.  He says that O-types produce this greater amount of acid as an adaptation to a high meat diet; A-types have less acid because they are adapted to a low protein, low meat diet. 

Apparently he missed the memo when research discovered that gastric ulcers arise from infection with H. pylori bacteria, not excessive stomach acid production.  While it is true that group O individuals have approximately 35% greater risk of gastrointestinal ulcer when compared to group A individuals, this is not because O-types produce more acid that A-types.   The ulcer-causing bacterium, H. pylori, can more easily attach to the G.I. lining of Group O, because it has a protein structure that mimics the Group O host (which confuses the host’s immune system).  In contrast, the immune system of A-type individuals more easily recognizes the bacterium as a foreign invader, making them more resistant to this infection.

D’Adamo correctly states that group A individuals have a higher risk of cancer than group O individuals.  Relative to Group O individuals, Group A individuals have higher risks of cancers of stomach , colon, ovary, uterus, cervix, and salivary glands (relative risks 1.2, 1.11, 1.28, 1.15, 1.33, and 1.64).  D’Adamo implies that this difference arises due to influence of dietary lectins. Presumably, the more vegetarian diet  he prescribes for A-types will protect them from cancer by reducing their exposure to harmful lectins.

First of all, if dietary lectins are the cause of cancers in anyone, it is very hard to understand how a vegetarian diet based on grains and beans will help prevent cancer.  Lectins are carbohydrate-binding proteins found in the highest concentrations in carbohydrate-rich foods like gains, legumes, and potatoes, not meat.  From Wikipedia entry on lectins:

“The toxicity of lectins has been identified by consumption of food with high content of lectins, which can lead to diarrhoea, nausea, bloating, vomiting, even death (as from ricin). Many legume seeds have been proven to contain high lectin activity, termed as hemagglutinating activity. Soybean is the most important grain legume crop, the seeds of which contain high activity of soybean lectins (soybean agglutinin or SBA). SBA is able to disrupt small intestinal metabolism and damage small intestinal villi via the ability of lectins to bind with brush border surfaces in the distal part of small intestine. Heat processing can reduce the toxicity of lectins, but low temperature or insufficient cooking may not completely eliminate their toxicity, as some plant lectins are resistant to heat.”

Therefore, the diet he apparently prescibes to A-types to reduce their risk of cancer actually provides MORE potentially hazardous dietary lectins than the diet he prescribes to O-types.

Secondly, D’Adamo doesn’t appear to know that the reason for increased risk of cancers in individuals with A-type blood is similar to the reason for the increased risk of ulcers in individuals with O-type blood.  Tumors often express an A-like antigen that the immune system of an A group individual will accept as “self” while the immune system of an O or B group individual will attack any cell with an A antigen. 

Note also that group O- and B- individuals still get these tumors. For example, the relative risk of stomach cancer is only 20% greater among A-type individuals compared to O-type.  This means that if 5 of 100 individuals having blood type O get stomach cancer, 6 of 100 individuals having blood type A get the same cancer; if 50 type Os get the cancer, 60 type As will get it.  In absolute numbers, the difference between these groups is not significant. 

Do Lectins Cause Selective Agglutination?

A lynch pin of D’Adamo’s hypothesis is the claim that lectins selectively cause agglutination in different blood types.  For example, according to D’Adamo, people with B-type blood should avoid chicken because it contains lectins that will agglutinate blood in these individuals, but not in people with other blood types.

We don’t have any evidence for this.  In fact, published data indicates that any individual lectin will affect all blood types in essentially the same way. 

Wikipedia discusses this topic:

“D'Adamo claims there are many ABO specific lectins in foods.[14] This claim is unsubstantiated by established biochemical research, which has not found differences in how the lectins react with a given human ABO type. In fact, research shows that lectins which are specific for a particular ABO type are not found in foods (except for one or two rare exceptions, e.g. lima bean), and that lectins with ABO specificity are more frequently found in non-food plants or animals.[15][16]

The Nachbar Study[17] has been cited in support of D'Adamo's theories, because it reports that the edible parts of 29 of 88 foods tested, including common salad ingredients, fresh fruits, roasted nuts, and processed cereals were found to possess significant lectin-like activity (as assessed by hemagglutination and bacterial agglutination assays). However, almost all of the 29 foods agglutinated all ABO blood types, and were not ABO blood type specific. Since D'Adamo's theory has to do with lectins in food that are "specific for a certain ABO blood type", this study does not support his claim that there are many ABO specific lectins in foods.”

Reference 15 in this excerpt refers to The Handbook of Plant Lectins

So Why Do People Feel Better?
D’Adamo advises the avoidance of wheat to O, A, and B blood types. Collectively, these comprise 96% of all people in the U.S..  Therefore, most people who read the book will get advice to avoid wheat, and they may try it.  This alone will improve health for some people who are wheat sensitive. 

Besides this, most people adopting the blood type diet will simply make general improvements to their diets, like reducing sugar intake, eating less processed and more unprocessed foods. D’Adamo suggests these steps to all blood types.  The general steps will help most people feel significantly better and perhaps lose some body fat. 

Bottom Line

The blood type diet does not have a solid leg on which to stand.  The hypothesis is riddled with errors. 

Addendum 10/28/11

Michael Klaper, M.D.: Challenges to the Blood Type Diet


Tyler said...

Hi Don-

Really good analysis, I have always wondered where he got the ideas about blood types and diet. I have talked to a few people that tried it because they were type O and thrived on it, but there partners weren't type O and still did just as well on the type O diet.

Don said...


Similar to your friends, I have O-type and my previous wife and co-author had A-Type, we both thrive on paleo and both suffered on vegetarian regimes, in fact I might say she fared even worse on vegetarian than I, contrary to what D'Adamo would predict.

Melissa said...

Haha, this is great. I can't believe people believe this stuff, but when they do I can just send them here.

"Blood type A is about agriculture because A is for agriculture!"

"Blood type B is about bullshit because B is for bullshit!"

jeff said...

Excellent critique of the Blood Type Diet hypothesis. Clearly the information put forth by D'Adamo is rubbish! Another case of pseudoscience being put forth as science. Glad to have this information available so that the next time a client asks about the Blood type Diet I can send them here.

David Csonka said...

I'm an "O" blood type, as in OMG Grainz!!

Jennifer said...

Thank you for this post. I just encountered a woman who swore up and down this diet was her savior. I didn't want to burst her bubble but I assumed the positive effects were from the more general changes like the wheat elimination. I couldn't remember the details of why this diet was bogus so I appreciate the refresher!

Anonymous said...

Well done Don, This blood typing stuff is not more than selling low-carb in another package. I'll place it on our CutTheCarb facebook page.

Anonymous said...

In one of his newsletters Cordain analyzed D'Adamo's diet and said that it remains successful largely due to 62% of the planet being type O. And thus they pretty much adopt a paleo diet. In many regions that would be a pretty high success rate.


Rain said...

I'm Type A, and Celiac. So much for grains being good for me. I have done fantastically on a Primal/Paleo diet.

Marsha Stopa said...

Thank you very much for this post. This clears my confusion.

I tried the Blood Type Diet for awhile, and it did explain why I had digestive problems with certain foods. (I'm Type A.)

But since I've been trying the primal diet, thanks to Mark's Daily Apple, I've noticed a huge difference in the way my body reacts to food and how I feel. I have virtually no gas and digestion is quietly invisible. My energy is steady, I've lost a lot of bloat and all cravings -- unless I eat grains, or a high sugar food.

Because of my initial success with the Blood Type Diet, I couldn't explain how a primal diet could work for me.

Thanks for this detailed explanation.

Alex said...

Another reason for success on the blood type diet is the recommendation to eat natural whole foods. Any dietary paradigm that gets people off processed crap is going to have some degree of success.

Avishek said...

Dr. D'adamo mentioned in a lecture on youtube that the gene that codes for blood type is pervasive throughout the body. He said it has a large role in the intestinal tracts as well and he could have called the book the intestinal type diet. So I think we still need further critique. I think you should look at his Genotype Diet book, where he does mention differences in tooth structure, leg structure, jaw, head shape, finger lengths, and blood type, secretor status and a few other things. He goes a bit beyond blood type there. For example, people with shovel shaped incisors should eat meat. I've never met anyone without a shovel shaped incisor though.

Don said...


Scientists have not discovered any nutritionally significant anatomical or physiological differences between, for example, Inuits who have live for millenia on 90% meat diets, and Chinese who have for millenia eaten 90% plant food diets. D'Adamo is engaged in what we philosophers call ad hoc hypothesizing. That means, his blood type hypothesis is full of holes, so he keeps coming up with more hypotheses to modify and qualify, all trying to save the first hypothesis, instead of just admitting that the hypothesis has not a leg to stand on. It becomes an ego thing, meaning, it is so hard to admit you are wrong after you built an empire on a false foundation. Can you imagine the inner strength it would take for him to tell all of his followers that he made a mistake and that neither blood type nor genotype affects your food requirements because after all you are a human.

Put it this way, no veterinarian would take seriously a hypothesis that black cats and orange cats have different nutritional requirements because their genes differ slightly. A cat is a cat, a carnivore, regardless of minor variations in hair color or length, facial form, length of legs, minor variations in teeth, eye color, etc. The same is true of humans, but for some reason (I think it has to do with the ego's need to feel special) people think these minor variations in humans add up to making each individual a species unto itself.

Dr. Curmudgeon Gee said...

Hi, Don,

nice article. thanks.

i believe Chinese diet is mostly plant-based only if you calculate on the "volume" (or "mass" ?)

if you count the calories, the intake from fat is much higher than the usual guideline of 30% fat.



Don said...


Do you have a reference for that claim?

Carolyn Blackburn said...

I was a follower of the blood group diet until I started reading about other ancient ways of eating that seemed to make more sense and were far easier to do. I'm glad I don't have to spend my life eating tofu (i'm type A). Thanks for your interesting blog.

Rabbi Hirsch said...

Has there ever been a study to look for the rate of success of his approach?

Mya said...

Your post would be more credible if most of your resources weren't quoted from Wikipedia. That's a bit like citing financial advice from "Joe B. The guy at my local pub. I am not saying I support this guy's diet (or any diet that is backed up by people urging us to buy the author's books and products) but, if you want to present a convincing case (at least to those of us w/ a science background) then stick to quoting peer reviewed studies.

Don said...


Did you read the Wikipedia entries? I don't normally cite it so often but in this case each excerpt from Wikipedia has the historical or hallowed peer-reviewed studies cited (I even left in the notations). Further, this is a blog, not a scientific treatise. I get that you think Wikipedia is the same as Joe B at the pub, but does Joe have references like Wiki articles? Easy to be a critic, how about coming up with some evidence that contradicts what I wrote?

K. Thomas said...

You have some narrow minded readers. This critique is weak, and nothing but wikipedia cut/n paste. If anything is bs, it's this article. I've been on the BTD for years, and it changed my life from sorry disease ridden state to leading a pretty much normal life. You can site as many useless wikipedia articles you can find, it won't change the fact that this diet works for thousands of people out there. The proof is in the pudding. There are always deviations to ANY diet, not one thing works for all.

Don said...

K. Thomas,

'Nothing but' a Wikipedia cut and paste? Give me a break. I only referred to Wikipedia three times, and two of those times, I backed the Wikipedia citation with reference to another source. Most of the article is reasoning I produced myself.

Like a previous reader, you mistakenly think you can dismiss information by attacking the source. "Its not true because Wikipedia said it" is not an argument or evidence, it is prejudice and logical fallacy. People seeking knowledge don't dismiss any assertion just because it comes from some widely vilified source, they evaluate the content of the assertion against evidence.

To whit: If Wikipedia says that the earth is round, do you dismiss it because it came from Wikipedia?

I cited directly the paper on the evolution of the ABO types. Basic reasoning proves that the O-type is not original. It is a fact that these types and their alleles occur in non-human primates, so how can anyone claim that these types are adaptations to human diets?

Alternatively, do you actually have evidence that those molecular biologists are wrong, and D'Adamo is right? Provide evidence and I will listen.

I cited Bloodbook, not Wikipedia, as the source for data on the distribution of blood types in various cultures. Show me the evidence that the Bloodbook data is wrong, i.e. that Inuit have only O type, or Chinese have predominantly A type.

I cited two sources including Wikipedia for simple historical information on what the Blackfeet people ate. I don't see anything wrong with that. If you have evidence that Blackfeet people ate something different from this, how about providing it? It doesn't exist, the diet of traditional Blackfeet natives is well established and correctly reported by Wikipedia. According to D'Adamo, these hunter-gatherer Blackfeet should have all O-type blood. Wrong.

I also cited the Wikipedia entry on lectins. It is entirely accurate. I know because I have read extensively on lectins, including from the book, The Handbook of Plant Lectins, which I linked to as support for the Wikipedia entry, and is written by the most highly respected authorities on plant lectins. If you read that source, and others like it, including the sources cited by Wikipedia, you will learn that the Wikipedia entry portions that I cited are well-supported. Again, if you have EVIDENCE that the Wikipedia entry has flaws, SHOW it and I will listen.

Like some other critics, you spout opinions without providing any evidence contradicting anything I reported. The fact that eating your BTD improved your health does not show that the BTD theory is correct, it only shows that if you eat the way you do, you feel better and are healthier than when you did not eat that way. There is a high probability that happened just because you stopped consuming wheat and other toxic foods, not because your are eating right for your blood type.

Dudley said...

Your article is seems bit unfair, Having dealt with Dr Peter D'Adamo and have him "successfully" help my daughter when absolutely no one else could. I have to say you may be mistaken. Having done some research myself your arguments are not as good as you may think but then again I have read all of Peter D'Adamos Books, including his Genotype books which are updated. Having said that the thing that seems a bit odd is how angry all your followers are. I hope you have a peaceful life but politely suggest you take a look at your conscience.

Dudley said...

Full of glib presumptions and straw-men with an emphasis on poking semantic holes in a mass-market book written for readers of average intelligence. Using a basic handbook of plant lectins and Wikipedia as the points of reference indicate at best a rudimentary understanding of the physiologic role of ABH antigen expression.

Where to start in this exercise in cheerless infanticide?

Saitou's work is valid from a 'genetic clock' perspective but using his molecular work completely misses the point. These digestive characteristics are more often the result of founder effect, the result of well-known predilections of the ABO groups for specific infectious diseases and their ancestral geographic and migratory distributions.

Very basic facts about the phenotypic aspects of ABO, such as pleiotropic elements of ABO expression, its role in multi-factorial inheritance and the broad basis of the phenotypic distinctions (including the 2-3 fold differences in intestinal phosphatases and brush border hydroxylases) should have been addressed if the author purported to be offering a fully developed debunking. However I see no evidence of this. Three-fold differences in coagulation factors and significant differences in the level of soluble endothelial adhesion factors again argue that type A's often make poor meat eaters and cannot tolerate significant elevations in serum cholesterol. I'll leave it to the author to discover why that might be the case. I suspect he might enjoy the discovery process. The recent findings by Reilly, et al. ( again show the relative difference in cardiovascular disease between the blood types. Recent links between ABO secretor status and Crohns disease continue to show that ABO antigen expression has profound effects on the gut epithelial and microbiome (

The reference to Gary Taubes blood work is especially specious, although I'm glad that he is so healthy. Other paleo-proponents, also type A, have had less luck. Robert Crayhon, also a type A paleo-proponent, recently passed away from colon cancer. Thus it seems to me that testimonies of this sort prove little beyond whatever point the protagonist wants to make.

Don said...


So far as I can tell, the references you gave and the items you discussed only point out that people of different ABO phenotype have different biochemical ranges and disease susceptibilities, which I never disputed, in fact I completely agreed. The question is whether these genetic differences warrant a different diet, and particularly whether dietary changes caused the evolution of the blood types, which is a central claim of D'Adamo.

To repeat myself: If diets low in animal products favor A-type survival and disfavor O-type survival, this predicts that we should find low percentages of A-type among meat-eating populations like Eskimos and high percentages among near vegetarian populations like Chinese, and the converse for O-types. But several examples I adduced above show this not to be the case.

The Chinese diet did not favor A-types, and the Alaskan Eskimo diet did not favor O-types. Since this natural experiment has been operating for millenia, this strongly contradicts the hypothesis that A-types have better survival on a vegetarian diet and O-types have better survival on a meat-based diet.

Only one black swan is necessary to disprove the hypothesis that all swans are white.

Dudley said...

What is your blood type Don?

Anonymous said...

Exactly, you have right. Here you have been quote one of the latest and very effective data. This is very nice post! I will bookmark this blog. back pain

Anonymous said...

I've done the blood type diet about a decade and have found it to be true. I've also genotyped myself as an O Hunter and really thrive on a high meat/fish diet. I eat moderate amounts of fats and carbs and exercise. My years as a vegan in the 80s and 90 were a full scale disaster socially, financially, health wise-- just in every way.

Factoid said...

You made an analysis based on speculatory information. Let me say it a few different ways. You made an analysis based on the information that was given as a guess as to what caused the facts we live with now of blood type. You made an analysis based on trivial information unrelated ( and known to be to Dr. D'Adamo) to plethora of studies showing the differences between blood groups, disease, and bodily functions.

Good job on proving you as expert of abstracting arbitrary information and using it for the basis of an argument.

By the way Dr. D'Adamo has accounted for higher frequency of meat eating Type A's with his later work. There were people who did poorly on the original book (written for a 6 year old comprehension level so it figures that is the one you criticized). After that he got to work to further understand genetics, coming upon some pretty drastic differences between some Type A's.

Further more your argument is sitting out in space like what you say is the will of the universe. We have enormous amounts of evidence supporting vegetarian and paleo diet success - Atkins too inherently then. Maybe it is a hard concept that different people do well on different diets for you, but maybe you are so egotistical that you think everyone should eat the diet you recommend, that makes you feel good, despite their success on their current one.

Grow up. If you want to criticize come with some real information, dig a little. Try reading any of the later books, the library of books, after the one you picked out because it is an easy target for stupid dick criticism. Hell try the diet and see how it goes if you want to be a true critique/skeptic.

Don said...


don mcgrath said...

Thanks for the education on what appears to be nutritional advice without substance. Nutrition is confusing and I appreciate the work to expose the flaws in this catchy diet.

jaredthompson87 said...

Watch this video.. it explains hidden food allergies in correlation to blood type. It begins talking about it on 20:00 but watch the whole thing if you want to be blown away. I myself took a Igg test and am O+ and found i was allergic to gluten and egg whites.

Karen said...

I too was surprised at the wiki info. Even if it is "just a blog" i would still want to present it in a better manner. Interesting to read though.

admin said...

Interesting read. might be a bit more convincing if you didn't have a background in philosophy.

skankexpose said...

Well I'm an O type and there is no way I'm giving up grass fed milk OR raw cheese. Uh way!

sheone said...

According to Saitou and Yamamoto, among this list of primates checked for ABO blood type, A phenotype occurred in 191 individuals, B in 75 individuals, AB in 44 individuals, and O in 20 individuals.

Jill-Kill said...

"Type B is the only blood type that can fully enjoy a variety of dairy foods."

...I'm a Type B, and I used to get frequent sinusitis until I eliminated dairy from my diet.

Now, I only eat goat cheese or yogurt on rare occasions, maybe once every 2 weeks. Any more and I start getting congested.

Also has avocados listed under food for B types to avoid. Are you freaking kidding me? Avocados are one of the best things for you on the planet!

Anonymous said...

By 1990 molecular biologists had determined that A-type is the
original blood type. Not type O. Type A came first. And then mutations
in the original A gene caused B and O to appear.
So the whole bottom line claim in this book that the original
blood type of early human is O is not based of fact. At one time it was
believed that type O was the 1st. This is no longer the case.

M said...

I've read other articles poo-pooing the blood type diet, but none with any facts until this one.

Don, what's your take on blood tests to determine food sensitivities?

Don said...


Blood tests can only determine true allergies, not all types of food sensitivities. The gold standard for food sensitivities is the elimination diet.

Edward said...

It should have stopped amazing me long ago, but it still does amaze me how fervently people believe and defend diets. It almost has the intensity of religion or politics. And I guess that IS why it is so intense.

For many people, diet is faith-based more than anything else. If something sounds good and makes them feel unique, they believe it and will defend it to the point of attacking and defaming detractors, without paying any more attention to what the detractor is saying, other than recognizing that they feel threatened by it.

Tom Martens said...

The very lectins that Dr. D’Adamo has found to cause problems with each blood type are the same food lectins used by scientists and doctors used in staining for antigens on cancer and pathogen cells.

Staining is the same as binding and scientists and doctors have been using food lectins to identify antigens on cancers and pathogens for over 50 years.

This is empirical, peer reviewed scientific evidence.

DiagnosisHuman said...

Admin said, "might be a bit more convincing if you didn't have a background in philosophy". Don, I'm curious if you would admit to any bias in your article?

Don said...


Bias? Yes, I am biased toward truth and against bullshit that misleads people. How does my having a background in philosophy, which is the foundation of all sciences, and includes the science of logic and critical thinking, make this less convincing?

Don said...

Not to mention my certification by the American Academy of Nutrition and my Master's degree in Oriental Medicine.

Check D'Adamo's motives. How many supplements does he sell? How does he spin his theory to sell crap?

And, what am I selling on this site? I'm not trying to sell you anything, I'm trying to save you money and time wasted following a diet plan that has no scientific basis.

Don said...


D'Adamo didn't "find" that lectins cause problems for each blood type. He made it all up.

The fact that scientists use lectins for staining does not show that these lectins cause disease in humans.

I repeat, there is no evidence that people of different blood types have different dietary requirements, just as there is no evidence that chimpanzees (or any other species) of different blood types have different dietary requirements.