Blood Type Diet FAQ


  1. The blood type diet hypothesis proposes that ABO type determines the individual's diet as each type evolved in response to available food sources; therefore the O type is a hunter-gatherer, the A type is dependent on cultivated crops, etc. This premise states that ABO type A appeared between 15,000-25,000 years ago, type B appeared 10,000-15,000 years ago, and type AB appeared only 1000-1200 years ago.
    FACT:All human ABO blood types existed as of several million years ago. From the time of the earliest humans, all ABO types existed as hunter-gatherers until the advent of agriculture. The earliest possible date for agricultural practices is 10000 BC (beginning of the Holocene era), from current research. Through core samplings of ice and the ocean it has been shown that the climate could not have supported agriculture earlier than this date. The climate was too variable during the last ice age, with dramatic changes in as short a time period as a decade, there was a scarcity of free water for irrigation, and atmospheric CO2 levels were very low.

    Agriculture Origins

    Interestingly enough, the A blood type appears to be the original and oldest human type, not O. This information has been available from microbiological research and analysis of DNA since 1990. The first blood type diet book, "Eat Right 4 Your Type", published in 1996, did not make use of current research, but instead used earlier works to establish its anthropological premise that O's should be on a meat-based diet as they were the original hunter-gatherers. In any case, since all ABO types existed and lived on the hunter-gatherer diet much earlier than the development of agriculture, there is no supportable evidence to have certain groups as vegetarian and others as meat-eaters based on emergence of ABO type.

    Yamamoto F, Clausen H, White T, Marken J, Hakomori S, Molecular genetic basis of the histo-blood group ABO system, Nature 1990 May 17;345(6272):229-33

    Naruya Saitou and Fumi-ichiro Yamamoto, Evolution of Primate ABO Blood Group Genes and Their Homologous Genes, Molecular Biology and Evolution, 14(4):399-411, 1997.

  2. The blood type diet hypothesis proposes that lectins in foods are specific to ABO blood types, and that different blood type people should eat different diets.
    1. What is a lectin?
      FACT: It's a protein that binds to sugars on sugar containing proteins (or glycoproteins). Glycoproteins tend to be associated with cell surfaces, or cell membranes. Lectins recognize specific sugars on cell surfaces, and if they match, bind to that particular sugar. Agglutination caused by lectins is inhibited by a specific sugar. This is what distinguishes lectins from antigens which are produced by all mammals. Some lectins can identify blood cells and can cause cell division in white blood cells.
      Lectins are present in nearly every organism, plant or animal, including humans-we produce lectins too.
    2. Which lectins react with, or agglutinate human blood cells?

      FACT: Surprisingly few lectins are blood type specific. Surprisingly fewer of those that are blood type specific are found in foods we eat. The vast majority of lectins in foods agglutinate all or no ABO types.

      This chart shows many foods, herbs which have lectin activity towards the human ABO blood group, showing the reactions to each blood type.

      Wheat germ agglutinin (wheat germ lectin) for instance, will agglutinate all human and animal red blood cells. It is not specific to only one ABO type. Soybean lectin is the same, it agglutinates all human ABO blood types and several animal species blood as well. So does rye lectin, so does chickpea lectin...

      Lectins can, and do, attach to antigens in the gut, primarily in the small intestine, and it does occur throughout the entire digestive system, from the oral cavity all the way to the 'end of the line.' Since the vast majority of lectins are NOT ABO specific, they are attaching to something other than your ABO antigens. And what they are attaching to is pretty species specific throughout humans-basic sugars, which are found in many antigens throughout your body, and even in the mucin lining your digestive other words, we can all eat basically the same, or a similar diet as far as regards lectins.

      Read what Dr. Arpad Pusztai, a famous lectin researcher, has to say about ABO blood type type specific lectins   (this page will open into a 2nd window).

    3. Just because a given food agglutinates my blood, does that necessarily make it a bad thing?

      FACT: If most food lectins agglutinate all or no blood types, why would anyone be able to eat tomatoes, or soybeans, or any of many different foods under this diet plan? Yet the blood type diet is set up that way, supposedly because the lectins are going to do bad things in your body. Since lectins are in almost everything, if you wanted to totally avoid all lectins there would not be much left to eat. As humans have been ingesting lectins since the beginning of their existence, it's hard to blame all the problems on foods which contain them.

      Take Wheat germ lectin, for instance. There is no plausible reason to exclude a food like 'wheat germ' from the diet of all humans except AB Lewis type secretors (which are less than 4% of the general population) based on lectin attachment (as directed in the second blood type diet book, "Live Right 4 Your Type"). The right reasons for excluding wheat from a human diet would be based on something else, such as allergy to wheat (less than 2% of the adult population, approximately 4% of the child population), or Celiac Disease (a genetic disorder which affects a tiny segment, 0.3% of the population... and the classic presentation of Celiac Disease is chronic diarrhea, with abdominal bloating, sometimes pain, weight loss, iron deficiency and other evidence of nutrient malabsorption).

      ??Intolerance or sensitivity to wheat has received much attention from the media recently. Perhaps as a direct result the number of people self-reporting an allergy or intolerance to wheat is increasing dramatically. However, there is no evidence that the true prevalence of wheat intolerance is on the increase and self-diagnosis or a flawed diagnosis from an unqualified alternative therapist can often do more harm than good, particularly if it results in poorer nutrition.
      ??Wheat has also been linked with gastrointestinal symptoms (people experiencing these symptoms are likely to have other intolerances such as a reaction to cows' milk protein), asthma, urticaria (skin rash) and eczema. There is no evidence to show wheat is a causal agent in such conditions. In some cases, a psychological aversion to wheat may be responsible for the reported symptoms. Such an aversion can have a powerful impact on both perceived symptoms and perceived relief of symptoms when wheat is avoided.??

  3. What about the digestive differences between the various ABO types?

    FACT: There are many ways scientific information can be presented, giving the impression that a certain premise is totally supported, when it may not be at all. For instance, here is some information on IAP (intestinal alkaline phosphatase) which is proposed as the reason As cannot digest foods as well as Os or Bs. The level of IAP as measured in the blood, therefore called "serum level of IAP" shows that Os and Bs do achieve higher levels, but then here is the trick--what we have not been told is that in the intestines, where digestion takes place, the amount of IAP is pretty much the same for each ABO type. From Human Blood Cells: Consequences of Genetic Polymorphisms and Variations. London: Imperial College Press, 2000.

    "Alkaline phosphatases are a group of (iso)enzymes that are present in many human tissues.... Serum alkaline phosphatase is derived from the liver, bone and the intestine. Intestinal alkaline phosphatase (IAP), found in all individuals, is believed to be required for the normal resorption of fat, particularly after a fatty meal (containing long chain fatty acids). This isoenzyme is not known as a serum marker for any pathological condition..... The IAP response to fat ingestion is ABO- and secretor status-dependent, with secretors of blood groups B and O having about five times more serum IAP than group A secretors or non-secretors of all groups, although they all have similar amounts of enzyme in the intestine." p 49-50

  4. With the Blood Type Diet, information is presented that due to A's weak body systems, they live the shortest lives.  O's on the other hand, live the longest, B's & AB's somewhere in between. Is this data true?

    FACT: No its not true. Actually, all the existing medical and scientific research has shown that ABO blood type has NOTHING TO DO WITH LONGEVITY OR LIFESPAN!

    For instance, there is a very large ongoing study of over 8000 men called the ‘Honolulu-Asia Aging Study' where the researchers have followed these men for 30 years so far. They had full data on the men in the study including their blood types. Lynne and I contacted Dr. Lon White who was one of the researchers in this study (an epidemiologist) and requested ABO info from him in February of 2000. At that time, the men in the study were all 80 years old or more.  Dr. White responded that he had checked, and there was NO ASSOCIATION BETWEEN ABO TYPE AND LONGEVITY. There were still over 3000 surviving members, and their blood types were a match for the percentages of ABO types in the beginning of the study. In other words, it did not matter if you were an A or an O, or a B, survival chances were equal, and therefore dependent on factors other than ABO type.

     Then there is another interesting recent study, done in 2003 which examined centenarians in Italy. The result of this study was published and it shows that the percentage of O's were equal to their percentage in the general world population, 43%.  The remaining 57% of centenarians were A's, B's and AB's.  So another valid survey showing there is no truth to the claims that O's live longer, and A's, much shorter lives. Actually, this Italian study is quite appropriate in showing the lack of validity of the blood type diet.  Wheat pasta and tomatoes make up a daily part of the life in Italy, and are cited in the blood type diet as being two of the worst possible foods for A types, yet it did not kill them off early!

    You can access the full article by going thru the abstract at pubmed linked below:

    Von Willibrand factor in Italian centenarians.