18 December 2002
Last Updated: 30 June 2010. Last Modified: 27 January 2013.


Blood Type Diet Review
Eat Right 4 Your Type
What it is, and what it's not.


NOTE: Food values (HB, N, A) listed in the 1996 version of Eat Right 4 Your Type do not always correspond with values presented in TYPEbase4, which is food-specific as opposed to type-specific. There was a time when we presented comprehensive type-specific lists for personal use, but copyright restrictions unfortunately necessitated their removal. If you click on any food in any food group in TYPEbase4, however, you can find current information for each blood type with respect to that particular food item. If you don't know whether you're a Secretor or Non-secretor, use the values for Secretor.

For your convenience, TYPEbase4 links are presented at right, a bit further down the page. You can use the following links to quickly locate a food group and find the specific food that interests you.


Introduction to the Blood Type Diet

Does your blood type represent a genetic marker that indicates which foods you can process best, and which might give you problems?  Does your blood type suggest predisposition to particular dysfunctions or vulnerability to certain diseases?  Can we identify a diet plan, determine appropriate vitamin and mineral supplements, and develop exercise regimens on the basis of blood type?  Even sketch out basic personality traits?


Eat Right 4 Your Type

In 1996, Peter J. D'Adamo ND (with Catherine Whitney) published a ground-breaking book entitled Eat Right 4 Your Type: The Individualized Diet Solution to Staying Healthy, Living Longer & Achieving Your Ideal Weight (NY: G.P. Putnam's Sons). This book soon became a New York Times bestseller, with over one million hardcover copies in print and translations in more than 40 languages.

Peter credits his father, James L. D'Adamo ND, with the basic predicate on which he has built his theory of blood types. The elder D'Adamo observed that patients responded differently to vegetarian and low-fat diets; he inferred that blood type might identify a biologic blueprint that determined the appropriate diet for a patient.

James L. D'Adamo is the author of One man's food — is someone else's poison (1980;226pp.) and The D'Adamo Diet (1989;186pp.); these may also be purchased from the D'Adamo Institute, located in New Hampshire. His third book, The Blood Type Diet: Your Personalized Diet and Exercise Program (1991), is out of print, but there's an interesting review here.

The Theory

In the introduction to Eat Right 4 Your Type, Peter J. D'Adamo writes that

[t]he essence of the blood type connection rests in these facts:
  • Your blood type - A, B, O, AB - is a powerful genetic fingerprint that identifies you as surely as your DNA.
  • When you use the individualized characteristics of your blood type as a guidepost for eating and living, you will be healthier, you will naturally reach your ideal weight, and you will slow the process of aging.
  • Your blood type is a more reliable measure of your identity than race, culture, or geography. It is a genetic blueprint for who you are, a guide to how you can live most healthfully.
  • The key to the significance of blood type can be found in the story of human evolution: Type O is the oldest; Type A evolved with agrarian society; Type B emerged as humans migrated north into colder, harsher territories; and Type AB was a thoroughly modern adaptation, a result of the intermingling of disparate groups. This evolutionary story relates directly to the dietary needs of each blood type today.

Lectins and Blood Type Antigen Reactivity

Fundamental to this theory is the idea that lectins, proteins found in many foods of high nutritional value, have glue-like properties that affect your blood. "Simply put," writes D'Adamo, "when you eat a food containing protein lectins that are incompatible with your blood type antigen, the lectins target an organ or bodily system (kidneys, liver, brain, stomach, etc.) and begin to agglutinate blood cells in that area" (p.23). Each of the four blood types is described in terms of an antigen. Type O is the simplest, comprised of a basic sugar called fucose. The Type A antigen consists of fucose and N-acetyl-galactosamine; Type B, of fucose and D-galactosamine; and Type AB, of fucose, N-galactosamine and D-galactosamine. Each of these antigens presents a "unique shape," and lectins fitting that shape can interact.

In my illustration below (adapted from p.26), food lectins interact with and agglutinate cells of one blood type at left; they do not interact with those of another type at right, because its cells possess a different shape.

Since each blood type antigen possesses a unique shape, may lectins interact with one specific blood type because they fit the shape of that particular blood type. In the example [below], food lectins from a steaming plate of lima beans interact and agglutinate Type A cells (on the left) because they fit the shape of the A antigen. The antigen for Type B blood (on the right), a different sugar molecule with a different shape, is not affected. Conversely, a food lectin (such as buckwheat) that can specifically attach to and agglutinate cells of Blood Type B would not fit Type A blood. (p.26)
Lectins
Once the intact lectin protein settles someplace in your body, it literally has a magnetic effect on the cells in that region. It clumps the cells together and they are targeted for destruction, as if they, too, were foreign invaders. This clumping can cause irritable bowel syndrome in the intestines or cirrhosis in the liver, or block the flow of blood through the kidneys - to name just a few of the effects. (p.24)

Differences among the Blood Types...

Mediated by genetic factors, each of the four Types presents a range of biophysical characteristics.

The mechanics of blood type’s influence have to do with the way the genes influence each other, seemingly unrelated, genes located immediately adjacent or nearby. This mechanism explains why your blood type can have an impact on such a diverse number of bodily systems – from digestive enzymes to neurochemicals. Many nutrition experts are baffled when they first hear about the link between blood type and digestion. That’s because they are only considering the physical significance of blood type as a surface antigen. Actually, it’s not your blood type antigen that is influencing the level of acid in your stomach, but rather the gene for your blood type influencing other seemingly unrelated genes located immediately adjacent (or very close) to the ABO blood type gene that can exert an effect on your stomach acid levels. This phenomenon, called gene linkage, isn’t well understood yet, but it is well known: Many genes influence the actions of other seemingly unrelated genes. [...]
Source: Blood Type B Basics, aboessentials.com

These biophysical characteristics suggest certain psychological proclivities and lifestyle choices.
For example:

Type As have a naturally high level of the stress hormone cortisol and produce more in response to stressful situations. Cortisol is released in 24-hour patterns, typically in the early morning between six and eight A.M. with a gradual decrease during the day. It helps to cue the body's other cyclical rhythms. Due to the naturally elevated cortisol in type As, additional stress often manifests in several ways; disrupted sleep patterns, daytime brain fog, increased blood viscosity (thickening), and promotes muscle loss and fat gain. In extreme cases in Type As, stress can manifest in more serious ways, causing obsessive-compulsive disorder, insulin resistance and hypothyroidism. To help balance cortisol levels, Dr. D'Adamo recommends that you limit sugar, caffeine and alcohol. Don't skip meals, especially breakfast; eating smaller, more frequent meals will also help to stabilize blood sugar levels. He also points out that the following factors are known to increase cortisol levels and increase mental exhaustion for Type As - be aware and limit your exposure when possible:

  • Crowds of people
  • Loud noise
  • Negative emotions
  • Smoking
  • Strong smells or perfumes
  • Too much sugar and starch
  • Overwork
  • Violent TV and movies
  • Lack of sleep
  • Extreme weather conditions (hot or cold)

For an overview of each Type, see:
Blood Type A Basics | Blood Type AB Basics | Blood Type B Basics | Blood Type O Basics
And for more on personality characterics associated with the blood types, see below.

Secretors and Non-secretors

D'Adamo has tested hundreds of foods to identify which lectins agglutinate which blood type. His results are presented in Eat Right 4 Your Type. The food lists were once presented online, but are no longer available as such; instead, you can use the TYPEbase4: Blood Type Diet/ Nutrient Value Encyclopedia to look up individual foods (see below). TYPEbase4 adds another variable, secretor/non-secretor, to the ABO types; this variable is not found in the 1996 work.

Secretor and Non-secretor values are presented for each food listed in the TYPEbase4. If you're unfamiliar with the terms Secretor and Non-secretor, consider this:

Source:
Secretors and Non-secretors
http://www.dadamo.com

...The gene coding for your blood type lies on chromosome 9q34. However, a separate gene actually interacts with your blood type gene, determining your ability to secrete your blood type antigens into body fluids and secretions.

In the genetics of the secretor system two options exist. A person can be either a Secretor (Se) or a Non-secretor (se). This is completely independent of whether you are a blood type A, B, AB, or O. This means that someone can be an A Secretor or an A Non-secretor, a B Secretor or a B Non-secretor etc.

In a simplified sense, a Secretor is defined as a person who secretes their blood type antigens into body fluids and secretions like the saliva in your mouth, the mucus in your digestive tract and respiratory cavities, etc. Basically what this means is that a secretor puts their blood type into these body fluids. A Non-secretor on the other hand puts little to none of their blood type into these same fluids. As a general rule, in the U.S. about 20% of the population are Non-secretors (with the remaining 80% being Secretors)... [Read more]

Secretor Test
Saliva Test for Secretor Status
While the average person may not really need this information in order to benefit from following the Blood Type Diet a realistic way, those with special needs and more serious health concerns may want to know their secretor status in order to open the door to even more specific dietary guidelines. [Read More]

Personality Assessment?
Footnotes are active links, and are fully cited by number in the table below.

D'Adamo notes the possibility but does not specify any connection between blood type and personality (1996:44-48). His web site includes a page entitled "Personality Assessment", which (accessed 15 April 2009) currently presents a quick MBTI test; previous content referred to personality descriptors for the blood types, citing the work Japanese and other authors on the subject. Visit the new Right 4 Your Type Store for the latest Blood Type Monographs, which include psychological correlations:

In Japan, ketsu-eki-gata is the theory that blood type can be used for personality analysis, and it is deeply rooted in popular consciousness.9 4 3 According to D'Adamo (1996:47), "[...] Although I think the Japanese ketsu-eki-gata is extreme, I can't deny that there is probably an essential truth to the theories about a relationship between our cells and our personalities. [...] The idea that your blood type may relate to your personality is not really so strange. Indeed, if you look at each of the blood types, you can see a distinct personality emerging — the inheritance of our ancestral strengths. Perhaps this is just another way for you to play to those strengths."

It is because these basic connections between blood type and diet were easily proven that experts began focusing on less obvious connections, such as personality traits. It was theorised that because evolutionary change altered immune systems and digestive tracts (hence the development of blood types), that mental and emotional characteristics would also be likely to change over such a long time. These basic changes could over millions of years develop into distinct behaviours and psychological patterns. Here is a guide to the personality traits that are supposedly common in the different blood types.

Type O blood types are defined generally as warriors. [...]

Type A blood types are defined as farmers. [...]

Type B blood types are defined as hunters. [...]

Type AB blood types are considered humanists. [...]5

Personality and compatibility assessments, hiring decisions and more are based on popularly accepted beliefs and observations regarding blood type differences. As Japan Times staff writer Mami Maruko tells us:

It wasn't until 1901 that U. S. scientist Karl Landsteiner (1868-1943) identified the various groups of human blood. In 1916, a Japanese doctor, Kimata Hara, published a research paper purporting to link blood group with temperament. Then, around 1925, Japan's army and navy began typing soldiers' blood, believing the information would be useful in identifying their strengths and weaknesses. However, no conclusive evidence of a connection between blood type and character resulted from all this research.

Still, the idea persisted. Most influential among those positing a link between blood and character was Takeji Furukawa, who in 1927 published a series of articles titled "The Study of Temperament Through Blood Type."

Based on studies from ancient Greece to Carl Jung, Furukawa assigned character traits to each blood group as follows:

Type O — calm, patient, in control of their emotions, strong-willed, unyielding and full of self-confidence despite a quiet appearance.

Type A — reserved, mild-mannered, full of worry, indecisive, cautious, deeply moved by things, uncombative and self-sacrificing.

Type B — cheerful, independent, light-hearted, talkative, sensitive, sociable, caring and flamboyant.

Type AB — Group B on the outside, but group A on the inside.

It wasn't too long before these stereotypes became ingrained in the nation's mind-set. As early as 1937, a part-time doctor at the Ministry of Foreign Affairs suggested that a group-O person would make a better diplomat.

In the 1970s, Masahiko Nomi expanded on Furukawa's ideas, describing group Os as extroverted, strong and expressive; group As as introverted, restrained and perfectionist; group Bs as free-thinking, independent and lacking ambition; and group ABs as sensitive, distant and passive. Thanks to growing media coverage, the idea that blood groups were linked to personality became widespread.

Today, people tend to fit others into blood group stereotypes, and comments such as "You are precise and passive, so you must belong to blood group A" now pop up in everyday conversation. Career and partner choices may also be influenced by blood. For example, group A people (gentle) are said to make good teachers and group Os (strong-willed) good army instructors.

Unsurprisingly, however, science does not support any of these beliefs. An individual's personality is formed by a complex mixture of genetic and environmental influences, and while blood group is genetically determined, any influence on personality must necessarily be very small, if it exists at all. Someone with group A blood may share character traits with another group A person, but certainly not because they share blood groups.

Masao Ohmura, a professor of personality psychology at Nihon University, tries to explain why these ideas became so popular in Japan and why they persist.

He suggests that because the Japanese are genetically quite a homogeneous people, grouping by blood was a way of achieving diversity — if only the illusion
of diversity. [...]4

Professor of psychology Kiyoshi Ando roundly criticizes this blood-type theory of personality, arguing that its application beyond the conversational, as, for example, in personnel management, will breed prejudice and discrimination through stereotypic reinforcement and self-fulfilling prophecy. There are, he adds, many Japanese who do not believe in these unproven correlations. People who '"try to know" the object' should exercise due care in the formulation of their judgments.3

References — Blood Group & Personality Type
  1. Japan blood type theory of personality
    From Wikipedia, the free encyclopedia
  2. You Are Your Blood Type
    Toshitaka Nomi, Alexander Besher
    Pocket Books (April 1988); English; ISBN: 0671633422, 203pp.
  3. "Blood-Typing" is Still Popular in Japan
    Kiyoshi Ando, Japan Labor Bulletin Vol.34-No.06 (01.06.95)
  4. Can blood type determine character?
    Mami Maruko, The Japan Times Online (16.09.01) You may have to register to view this article.
  5. Personality Assessment through Blood Type Analysis
  6. Blood Type and Character, Do u think it matches yours?
  7. Meaning of Blood Types
  8. Blood Character Analysis
  9. Type casting
    Mick Corliss, Metropolis
  10. Now only available in Japanese :
    ABO World

Criticisms of the Blood Type Diet

The blood type theory propounded by Peter J. D'Adamo is not without controversy. Though the theory is described as "scientific", many disagree with the predicate that these typal distinctions constitute a valid foundation on which to base dietary or lifestyle decisions.

Michael Klaper MD, member of staff at DrFuhrman.com, has written three very useful critiques along those lines:

Joel Fuhrman MD is a board–certified family physician who specializes in preventing and reversing disease through nutritional and natural methods. He provides a detailed seven-page critique of the Blood Type Diet in his book, Eat To Live: The Revolutionary Plan for Fast and Sustained Weight Loss (2005:107-113). First, he summarizes the four very different eating plans D'Adamo promotes for the four different blood types:

  1. Type O blood people (the Hunters) are designed for a lot of meat and will hurt themselves with wheat and beans. He asserts that "the gluten lectins inhibit your insulin metabolism, interfering with the efficient use of calories for energy....Certain beans and legumes, especially lentils and kidney beans, contain lectins that deposit in your muscle tissues, making them more alkaline and less 'charged' for physical activity. Type O's have a tendency to low thyroid function."
  2. People with type A blood (the Cultivators) should eat a vegetarian diet, as they are biologically predisposed to heart disease, cancer, and diabetes. D'Adamo interestingly lists vegetable oil as a food that encourages weight loss for this blood type.
  3. Type B blood people (the Nomads) do well with a varied diet and extra dairy products. They are resistant to heart disease and cancer, but more prone to immune system disorders like multiple sclerosis and lupus. Meat and liver encourage weight loss in Type B blood individuals, according to D'Adamo, and he recommends that Caucasians and African individuals with blood type B consume six to ten ounces of cheese weekly.
  4. People with type AB blood require a mixed diet, some meat, but not chicken. D'Adamo writes: "So, although you are genetically programmed for the consumption of meats, you lack enough stomach acid to metabolize them efficiently, and the meat you eat tends to get stored as fat." (p.107)

Fuhrman finds D'Adamo's approach an interesting mix, with some factual blood type information and "a whole lot of far-fetched assertions that have no basis in fact" (p.109). The main problem is that D'Adamo presents little or no scientific evidence in support of his assertions, many of which are implausible and, particularly with respect to human physiology, simply unscientific or frankly incorrect. Fuhrman provides several examples.

And then there's the matter of lectins: D'Adamo "does not produce a single scientific reference to establish his basic premise that sensitivity to plant lectins on hundreds of foods is governed by blood type." His assertions are inconsistent with the scientific literature.

Again, part of what D'Adamo says is true, but his interpretation is so exaggerated and distorted as to make his assertions almost valueless. Not all lectins are toxic; most are even nutritious, with significant beneficial effects. Only some lectins are truly toxic, such as in red kidney beans, and need to be destroyed by cooking prior to eating. But most other lectins, such as tomato lectins, have been shown to be harmless. The beneficial effects of plant lectins include anti-tumor and anti-cancer activity, meaning they inhibit the induction of cancer by carcinogens... (p.112)

D'Adamo claims there is a scientific basis to the effects of lectins on different blood types, writes Fuhrman, but his evidence is based on urinary indican readings in his patients — an "outmoded and notoriously unpredictable" test that registers neither antibody-antigen reaction nor agglutination and is also affected by unabsorbed protein (idem).

Since D'Adamo does not back up his claims that there is an association between ABO blood types and various diseases, Fuhrman undertook a Medline review of the scientific literature from the past 30 years. His findings, after reading more than 200 articles, are that the evidence in support of D'Adamo's assertion is equivocal. He concludes that while genetic factors do play a role in the development of heart disease and certain illnesses for some people, the heterogeneity of heart disease or atherosclerosis indicates that there are many genes which affect risk; blood may be among them, but "represents a small percentage of the genetic susceptibility on the human genome" (p.109).

When considering all the genetic risk factors together, we must conclude that environmental influences on atherosclerosis are much stronger than the genetic ones. Even if we combined all the genetic influences and stratified the risk of heart diesease or cancer in individuals in a more accurate way than blood type alone, we would still find the environmental factors are more important. Cholesterol levels, body weight, smoking, physical activity, food choices, and blood pressure have been shown to have a much stronger influence on disease risk than blood grouping. (idem)

And see:

  1. Eat Right for Your Type?
    Excerpt from The Food Revolution: How Your Diet Can Help Save Your Life and Our World
    John Robbins, Conari Press. (2001: 340pp.)
  2. The Blood Type Diet: Latest Diet Scam
    Deirdre B. Williams ND, John J. McMahon ND, VegSource.com (no date)
  3. blood type diet
    The Skeptic's Dictionary - Skepdic.com, Last Updated: 23.02.09 (Accessed: 13 April 2009)
  4. The Eat Right for Your Blood Type Diet
    WebMD, Reviewed by Jonathan L. Gelfand MD (6 February 2009)
  5. The Blood Type Diet: This popular eating plan ought to be sacked
    Andrew Weil MD, AARP (September & October 2008)

For additional information on lectins, and for purposes of comparison, see:

  1. The Lectin Story
    Krispin Sullivan CN (29 July 2008) — Defines lectins, examines and describes a self-test for lectin intolerance. Switching to the Paleolithic Diet has helped his more difficult clients achieve the very best results.
  2. The Paleolithic Diet Page: What the Hunter/Gatherers Ate
    Don Wiss. Also see PaleoFood.com: The Paleolithic Eating Support List's Recipe Collection — Recipes are grain-free, bean-free, potato-free, dairy-free, and sugar-free. Ingredients include meat, fish, fruit, vegetables, nuts, and berries.

D'Adamo has responded to his critics:

  1. Response to Various Criticisms
    Peter J. D'Adamo ND, Eat Right For Your Type :: The Official Blood Type Diet Site (no date)
  2. Andrew Weil on the Blood Types: Not Even Wrong
    D'Adamo's rejoinder, The Weekly Transfusion (blog)

My Experience with the Blood Type Diet

Scottish, Irish, English and Dutch on my father's side, Norwegian and Finnish on my mother's, I wonder: Given such a genetic melange, can my general health or my predispositions to disease and dysfunction be apprehended chiefly in terms of blood type?

When I was 18, I was told by what I presumed was a reliable source that my blood type was B; having no information to the contrary, no reason to doubt the source, I accepted that idea for years. When I began working with Eat Right 4 Your Type in 1997, I still believed I was type B. And why not? The Blood Type Diet B food list closely approximated the dietary pattern I had followed since childhood, and I had enjoyed excellent health for almost 50 years.

But something began to change in my late 50s. I no longer felt like eating the same foods. Dairy and wheat, in particular, became problematic. Then, about a year and a half ago, I asked my physician for my blood type; he didn't have it on file, so I asked him to run it. The result: I am type A, not type B.

Though the A list of foods holds some resonance for me, it is not my dietary blueprint. There are highly beneficial and neutral foods I simply don't like and on which I do not do well; there are avoid foods I find quite digestible and helpful. Even so, while dairy, wheat, potatoes, and meat were once important parts of my diet, they are now foods I limit or eschew altogether. These days I eat more vegetables and fruit, tofu, fish, lentils, mushrooms, rye, ginger, nuts, seeds... I eat meat medicinally, much as vegetarian George Bernard Shaw consumed raw liver on prescription from his doctor.

Many people swear by the Blood Type Diet, claiming it has helped them achieve optimal body weight and maintain good health. D'Adamo's ideas are provocative and his text remains a reference in my library.

His latest work, built on the foundation of the Blood Type Diet and utilizing data from the Human Genome Project, is The GenoType Diet (2007:352pp). Six genetic types (Hunter, Gatherer, Teacher, Explorer, Warrior, Nomad) are described and discussed, with respective food lists, meal plans, exercise plans, and a detailed resource list.

From aboessentials.com
Dr. Peter J. D'Adamo rocked the diet world more than ten years ago when he discovered that blood type was a determinant for the kind of food that would help maximize health and weight loss. Since then, Dr. D'Adamo has used the new and exciting research from the human genome project to further refine his system of types.

With The GenoType Diet, he introduces the first ever method for determining your GenoType at home, without expensive testing, and tailoring your life style to your findings. The six genetic types give readers a complete picture of how their GenoType evolved, their predisposition for weight loss/gain, immune function, disease propensity, and a comprehensive diet, exercise and life style profile tailored to fit their type.

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