Blood type diet
Encyclopedia
The blood type diet is a nutritional diet
advocated by Peter D'Adamo, a naturopathic physician, and outlined in his book Eat Right 4 Your Type. D'Adamo claims that ABO blood type
is the most important factor in determining a healthy diet, and he recommends distinct diets for each blood type.
Throughout his books D'Adamo cites the works of biochemists and glycobiologists
who have researched blood groups, claiming or implying that their research supports this theory. Nevertheless, the consensus among dietitians, physicians, and scientists is that the theory is unsupported by scientific evidence.
and to a lesser extent with an individual's secretor status. In his book, Eat Right 4 Your Type, "Lectins: The Diet Connection", and in following chapters, lectins which interact with the different ABO type antigens are described as incompatible and harmful, therefore the selection of different foods for A, AB, B, and O types is important to minimize reactions with these lectins.
D'Adamo bases his ideas on the ABO classification of Karl Landsteiner
and Jan Janský
, and some of the many other tissue surface antigens and classification systems, in particular the Lewis antigen system
for ABH secretor status.
On page 20 of Eat Right 4 Your Type, D'Adamo states "at this point, you might be wondering about other blood type identifiers, such as positive/negative, or secretor/non-secretor. ... These variations or subgroups within blood types play relatively insignificant roles. More than 90% of the factors associated with your blood type are related to your primary blood type, O, A, B, or AB."
The evolutionary theory of blood groups that is also used by D'Adamo stems from work by William C. Boyd
, an immunochemist and blood type anthropologist who made a worldwide survey of the distribution of blood groups. In his book Genetics and the races of man: An introduction to modern physical anthropology, published in 1950, Boyd describes how by genetic analysis of blood groups, human races are populations that differ according to their allele
s. On this basis, Boyd divided the world population into 13 geographically distinct races with slightly different frequency distributions of blood group genes.
D'Adamo groups those thirteen races together by ABO blood group, each type within this group having unique dietary recommendations:
Also, by limiting the very complex human beings to just four limiting stereotypes, the blood type diet has been likened to a "blood type astrology".
There is a lack of scientific evidence on the associations between disease states and ABO blood types as mentioned in Peter D'Adamo's website. A search of PubMed
under the author's name does not yield any peer-reviewed articles with data to support his claims. For example, his claim that elderberry can be used as a remedy for the common flu lacks scientific evidence and may be misleading. A review article by Dr. Guo and colleagues, published in the American Journal of Medicine, reports "the effectiveness of any complementary and alternative therapy for treating or preventing seasonal influenza is not established beyond reasonable doubt. Current evidence from randomized controlled trials is sparse and limited by small sample sizes, low methodological quality, or clinically irrelevant effect sizes."
), and that lectins with ABO specificity are more frequently found in non-food plants or animals.
The Nachbar Study 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.
D'Adamo has remarked in the past that it is an oversimplification of his work with blood groups to simply apply the lectin-blood group specifics ad hoc to his work, since that "would not be following the Blood Type Diet, but rather a lectin-avoidance diet". He has been quoted many times as saying that the Blood Type Diet is characterized more by "what you eat rather than what you avoid", and that "the lectin connection was only a part of a much larger picture."
s of human and non-human ABO alleles show that the A gene was the first to evolve. The authors argue that, in the evolutionary sense, it would be extraordinary for normal genes (those for types A and B) to have evolved from abnormal genes (for type O).
Yamamoto et al. further note:
Another study from 2004 concluded that: "Assuming constancy of evolutionary rate, diversification of the representative alleles of the three human ABO lineages (A101, B101, and O02) was estimated at 4.5 to 6 million years ago." This finding directly contradicts D'Adamo's assertion of blood type evolution.
However, the author has stated in the past that it is an oversimplification to characterize his description of the evolution of the blood groups as a matter of mutational selection, and that this often represents attempts to discredit the theory by cherry-picking obfuscations that inevitably result when one is forced to depict scientifically complex material in context of a mass-market diet book. D'Adamo has been quite clear in the past that these conclusions were drawn from studies of the epidemiologic effects of migration patterns and infectious disease susceptibility in relation to blood groups distribution and the migration patterns, not natural selection via mutation in any Mendelian sense.
Diet (nutrition)
In nutrition, diet is the sum of food consumed by a person or other organism. Dietary habits are the habitual decisions an individual or culture makes when choosing what foods to eat. With the word diet, it is often implied the use of specific intake of nutrition for health or weight-management...
advocated by Peter D'Adamo, a naturopathic physician, and outlined in his book Eat Right 4 Your Type. D'Adamo claims that ABO blood type
Blood type
A blood type is a classification of blood based on the presence or absence of inherited antigenic substances on the surface of red blood cells . These antigens may be proteins, carbohydrates, glycoproteins, or glycolipids, depending on the blood group system...
is the most important factor in determining a healthy diet, and he recommends distinct diets for each blood type.
Throughout his books D'Adamo cites the works of biochemists and glycobiologists
Glycobiology
Defined in the broadest sense, glycobiology is the study of the structure, biosynthesis, and biology of saccharides that are widely distributed in nature...
who have researched blood groups, claiming or implying that their research supports this theory. Nevertheless, the consensus among dietitians, physicians, and scientists is that the theory is unsupported by scientific evidence.
Description
D'Adamo's premise is that human blood type is key to the body's ability to differentiate self from non-self. Lectins in foods, he asserts, react differently with each ABO blood typeABO blood group system
The ABO blood group system is the most important blood type system in human blood transfusion. The associated anti-A antibodies and anti-B antibodies are usually IgM antibodies, which are usually produced in the first years of life by sensitization to environmental substances such as food,...
and to a lesser extent with an individual's secretor status. In his book, Eat Right 4 Your Type, "Lectins: The Diet Connection", and in following chapters, lectins which interact with the different ABO type antigens are described as incompatible and harmful, therefore the selection of different foods for A, AB, B, and O types is important to minimize reactions with these lectins.
D'Adamo bases his ideas on the ABO classification of Karl Landsteiner
Karl Landsteiner
Karl Landsteiner , was an Austrian-born American biologist and physician of Jewish origin. He is noted for having first distinguished the main blood groups in 1900, having developed the modern system of classification of blood groups from his identification of the presence of agglutinins in the...
and Jan Janský
Jan Janský
Prof. MUDr. Jan Janský was a Czech serologist, neurologist and psychiatrist. He is credited with the first classification of blood into the four types of the ABO blood group system.Janský studied medicine at Charles University in Prague. From 1899 he worked in a psychiatric clinic in Prague...
, and some of the many other tissue surface antigens and classification systems, in particular the Lewis antigen system
Lewis antigen system
The Lewis antigen system is a human blood group system based upon genes on chromosome 19 q13.3, and 19p13.3 , which both have fucosyltransferase activity. There are two main types of Lewis antigens, Lewis a and Lewis b. They are red cell antigens which are not produced by the erythrocyte itself...
for ABH secretor status.
On page 20 of Eat Right 4 Your Type, D'Adamo states "at this point, you might be wondering about other blood type identifiers, such as positive/negative, or secretor/non-secretor. ... These variations or subgroups within blood types play relatively insignificant roles. More than 90% of the factors associated with your blood type are related to your primary blood type, O, A, B, or AB."
The evolutionary theory of blood groups that is also used by D'Adamo stems from work by William C. Boyd
William C. Boyd
William Clouser Boyd was an American immunochemist, who with his wife Lyle, during the 1930s, made a worldwide survey of the distribution of blood types. Born in Dearborn, Missouri, he discovered that blood groups are inherited and not influenced by environment...
, an immunochemist and blood type anthropologist who made a worldwide survey of the distribution of blood groups. In his book Genetics and the races of man: An introduction to modern physical anthropology, published in 1950, Boyd describes how by genetic analysis of blood groups, human races are populations that differ according to their allele
Allele
An allele is one of two or more forms of a gene or a genetic locus . "Allel" is an abbreviation of allelomorph. Sometimes, different alleles can result in different observable phenotypic traits, such as different pigmentation...
s. On this basis, Boyd divided the world population into 13 geographically distinct races with slightly different frequency distributions of blood group genes.
D'Adamo groups those thirteen races together by ABO blood group, each type within this group having unique dietary recommendations:
- Blood group O is described by D'Adamo to be the hunter, the earliest human blood group. The diet recommends that this blood group eat a higher protein diet, presumably since O blood typeBlood typeA blood type is a classification of blood based on the presence or absence of inherited antigenic substances on the surface of red blood cells . These antigens may be proteins, carbohydrates, glycoproteins, or glycolipids, depending on the blood group system...
is described as the first blood type, originating 30,000 years ago. (However, research indicates that blood type A is actually the oldest.) - Blood group A is called the agrarian or cultivator, a more recently evolved blood type, dating back from the dawn of agriculture, 20,000 years ago. The diet recommends that individuals of blood group A eat a diet emphasizing vegetables and free of red meat, a more vegetarianVegetarianismVegetarianism encompasses the practice of following plant-based diets , with or without the inclusion of dairy products or eggs, and with the exclusion of meat...
food intake. - Blood group B is the nomad associated with a strong immune system and a flexible digestive system. The diet asserts that people of blood type B are the only ones who can thrive on dairy products and estimates blood type B arrived 10,000 years ago. (However, people with blood type B tend to be from Asia (specifically, China or India), and not from northern Europe, whereas lactose intoleranceLactose intoleranceLactose intolerance, also called lactase deficiency or hypolactasia, is the inability to digest and metabolize lactose, a sugar found in milk...
is most common among people of Asian, South American, and African descent and least common among those descended from northern Europe or northwestern India.) - Blood group AB is the enigma, the most recently evolved type, arriving less than 1,000 years ago. In terms of dietary needs, his blood type diet treats this group as an intermediate between blood types A and B.
Scientific criticism
The Blood Type Diet has met with criticisms for many different reasons, some of which have been addressed publicly by D'Adamo.Research evidence
One criticism of D'Adamo's hypotheses and recommendations claims that he provided inadequate evidence. For example, his first book, Eat Right 4 Your Type, published in 1997, contains only a bibliography. While his subsequent books have provided thorough references for the classifications of various foods within his categories of "beneficials", "neutrals", and "avoids", his specific process and reasons for reaching these conclusions of classification remain undocumented.Also, by limiting the very complex human beings to just four limiting stereotypes, the blood type diet has been likened to a "blood type astrology".
There is a lack of scientific evidence on the associations between disease states and ABO blood types as mentioned in Peter D'Adamo's website. A search of PubMed
PubMed
PubMed is a free database accessing primarily the MEDLINE database of references and abstracts on life sciences and biomedical topics. The United States National Library of Medicine at the National Institutes of Health maintains the database as part of the Entrez information retrieval system...
under the author's name does not yield any peer-reviewed articles with data to support his claims. For example, his claim that elderberry can be used as a remedy for the common flu lacks scientific evidence and may be misleading. A review article by Dr. Guo and colleagues, published in the American Journal of Medicine, reports "the effectiveness of any complementary and alternative therapy for treating or preventing seasonal influenza is not established beyond reasonable doubt. Current evidence from randomized controlled trials is sparse and limited by small sample sizes, low methodological quality, or clinically irrelevant effect sizes."
Questions of lectin actions
D'Adamo claims there are many ABO specific lectins in foods. 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 beanLima bean
Phaseolus lunatus is a legume. It is grown for its seed, which is eaten as a vegetable. It is commonly known as the lima bean or butter bean.-Origin and uses:...
), and that lectins with ABO specificity are more frequently found in non-food plants or animals.
The Nachbar Study 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.
D'Adamo has remarked in the past that it is an oversimplification of his work with blood groups to simply apply the lectin-blood group specifics ad hoc to his work, since that "would not be following the Blood Type Diet, but rather a lectin-avoidance diet". He has been quoted many times as saying that the Blood Type Diet is characterized more by "what you eat rather than what you avoid", and that "the lectin connection was only a part of a much larger picture."
Lack of clinical trials
Another criticism is that there are no clinical trials of the Blood Type Diet. In his first book Eat Right 4 Your Type, D'Adamo mentions being in the eighth year of a 10 year cancer trial, but the results of this trial have never been published. In his book Arthritis: Fight It With the Blood type Diet, D'Adamo mentions an impending clinical trial of the Blood Type Diet in order to determine its effects on the outcomes of patients with rheumatoid arthritis, but the results of this 12 week trial have never been published.Blood type evolution issues
In a Brazilian medical research journal, Luiz C. de Mattos and Haroldo W. Moreira point out that D'Adamo's assertion that the O blood type was the first human blood type requires that the O gene evolved before the A and B genes in the ABO locus. However, phylogenetic networkPhylogenetic network
A phylogenetic network is any graph used to visualize evolutionary relationships between nucleotide sequences, genes, chromosomes, genomes, or species . They are employed when reticulate events such as hybridization, horizontal gene transfer, recombination, or gene duplication and loss are...
s of human and non-human ABO alleles show that the A gene was the first to evolve. The authors argue that, in the evolutionary sense, it would be extraordinary for normal genes (those for types A and B) to have evolved from abnormal genes (for type O).
Yamamoto et al. further note:
Although the O blood type is common in all populations around the world, there is no evidence that the O gene represents the ancestral gene at the ABO locus. Nor is it reasonable to suppose that a defective gene would arise spontaneously and then evolve into normal genes.
Another study from 2004 concluded that: "Assuming constancy of evolutionary rate, diversification of the representative alleles of the three human ABO lineages (A101, B101, and O02) was estimated at 4.5 to 6 million years ago." This finding directly contradicts D'Adamo's assertion of blood type evolution.
However, the author has stated in the past that it is an oversimplification to characterize his description of the evolution of the blood groups as a matter of mutational selection, and that this often represents attempts to discredit the theory by cherry-picking obfuscations that inevitably result when one is forced to depict scientifically complex material in context of a mass-market diet book. D'Adamo has been quite clear in the past that these conclusions were drawn from studies of the epidemiologic effects of migration patterns and infectious disease susceptibility in relation to blood groups distribution and the migration patterns, not natural selection via mutation in any Mendelian sense.
Further reading
- D'Adamo, P. (with additional material by Catherine Whitney) (1996). Eat Right 4 your Type. Putnam. ISBN 0-399-14255-X
- D'Adamo, P. (with additional material by Catherine Whitney) (2000). Live Right 4 your Type. Putnam. ISBN 0-399-14673-3
- D'Adamo, P. (with additional material by Catherine Whitney) (2002). The Eat Right 4 Your Type Complete Blood Type Encyclopedia. Riverhead. ISBN 1-57322-920-2
- D'Adamo, P. "Nontransfusion Significance of ABO and ABO-Associated Polymorphisms" Chapter 43 In: Pizzorno JE, Murray MT (Eds.) Textbook of Natural Medicine, 3rd Edition, Volume 1 (2006) Elsevier. ISBN 0-443-07300-7 http://www.naturalmedtext.com
- D'Adamo, P. "Metabolic and immunologic consequences of ABH secretor and Lewis subtype status." Altern Med Rev. 2001 Aug;6(4):390-405. http://www.ncbi.nlm.nih.gov/pubmed/11578255
- Weissberg, Steven M. and Joseph Christiano (1999). The Answer is in Your Bloodtype. Personal Nutrition USA. ISBN 0-967-01250-3