Keys to evaluating material critical to the Blood Type Theory (or any other scientific hypothesis)
A few of the more frequently seen criticisms:
0. | |
Title | PLOS Study Debunking the Blood Type Diet |
Link | Link (HTML) |
Authors | Ahmed El-Sohemy, et al. |
Distribution | PLOS ONE |
Author Qualifications | Dr. El-Sohemy is a nutrigenomics researcher and an associate professor at the University of Toronto. He is a principal in Nutrigenomix, a company that markets genetic testing kits and dietary guideline to dieticians. |
Criticism Type | Scientific Study |
Article Synopsis | "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." |
Response | A look at the core data used in the PLOS Study [1] debunking the Blood Type Diet (BTD) finds support for the researcher’s conclusions that if your experimental subjects eat potato chips, sandwiches, pizza, ‘beans,’ mac-and-cheese, French Fries and processed meat products while doing 13.7% of the Blood Type Diet, their final cardiometabolic markers will probably not vary much by blood type. In other words, whilst the PLOS Study may have debunked something, it wasn’t the Blood Type Diet. I've responded to this study on my blog: You can read a technical analysis of the various methodological flaws in this study here: |
1. | |||||||||||||||||||
Title | Dr. Debunker: Does the blood type diet really work? | ||||||||||||||||||
Link | Link (HTML) | ||||||||||||||||||
Authors | Weil, Andrew, MD (Tucson, USA) | ||||||||||||||||||
Distribution | AARP Website, AARP Magazine (Sept-Oct 2008) | ||||||||||||||||||
Author Qualifications | Dr. Weil is a medical doctor. He has written numerous books on alternative medicine. He has not authored any peer-reviewed scientific papers on blood groups, nutrition or lectins. He has not conducted any clinical research on blood groups and diet. | ||||||||||||||||||
Criticism Type | Diet Wars (Diet Book Author) | ||||||||||||||||||
Article Synopsis | "D'Adamo theorizes that the basis for such differences is our reactions to certain food proteins called lectins. Lectins are common in plant foods, especially grains and beans, and may be involved in food allergies and some immune disorders. But there is no convincing evidence for any interactions between lectins and the molecules that determine blood type. Yet some people swear the blood type diet has worked for them. There's a reason for that. Making changes in how we eat is not easy. To follow any prescribed dietary program with rules and restrictions represents a significant commitment of mental energy toward self-improvement. That alone can lead to a greater sense of well-being and better health. But if you want to eat a better diet, I recommend you rely on information grounded in nutritional science." | ||||||||||||||||||
Response | Dr. Weil is a well-known holistic doctor and author of numerous books on diet. In a short article on the AARP online magazine, Dr. Weil again argues that the Blood Type Diet should 'be sacked.' His opinion piece is shot-full of logical fallacies, including the fallacy of one-sidedness and the argument from incredulity (sometimes called "argument from ignorance"). Jettisoning his previous criticisms, including the rather odd observation that animals have blood types and yet don’t follow the Blood Type Diet, Dr. Weil now offers his opinions on the lack of association between lectins and blood types. Dr. Weil's claim that there are no proven relationships between lectins and the molecules that determine blood type was apparently taken from an incorrect assertion that often finds its way onto the Wikipedia entry on the Blood Type Diet. This is hardly a hard-science resource. In fact, blood group specificity is listed as one of the nine major factors influencing glycosylation in the gut (glycosylation is the process of manufacturing the sugar molecules that lectins bind with). Other factors include diet, age, animal species, disease and bacterial population. (Trends in Glycoscience and Glycotechnology; 8:149-165) Dr. Weil is apparently still ignorant of the secretory differences (digestive enzymes, etc.) between the blood groups, perhaps the most significant reason behind the need for the tailoring nutritional needs to these genetic markers.[1] Dr. Weil may wish to consult the work of William Boyd, who first wrote of the blood type specificity of lectins more than a half century ago[3] or reviewed the research of Martin Nachbar[4] from the 1980's before making such claims, since he is essentially just plain wrong. A trip to MEDLINE might have might have also proved helpful.[5], [6], [7] William Boyd's 1945 work book has been preserved clearly showing blood type specificity of lectins he researched. | ||||||||||||||||||
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2. | |||||||||||||||||||
Title | The Blood Type Diet: Latest Diet Scam | ||||||||||||||||||
Link | Link (HTML) | ||||||||||||||||||
Authors | McMahon, John J. ND (Wilton CT, USA) Williams, Deirdre B. ND (Wilton CT, USA) | ||||||||||||||||||
Distribution | Extensively cross-posted throughout the internet, principally on vegan websites | ||||||||||||||||||
Author Qualifications | Both authors are naturopathic physicians. Neither have authored any peer-reviewed scientific papers on blood groups, nutrition or lectins. Dr. McMahon has an undergraduate degree in anthropology. | ||||||||||||||||||
Criticism Type | Opposing diet theory (veganism) | ||||||||||||||||||
Article Synopsis | "We are naturopathic physicians. We are also vegan as are our children. The practice of naturopathy as originally described by Dr. Benedict Lust includes 'the elimination of... habits such as over-eating, alcoholic drinks and... meat eating'. When we attended the John Bastyr College of Naturopathic Medicine the work of Henry Lindlahr, M.D. was required reading. Dr. Lindlahr defined the philosophy of Nature Cure or naturopathy as favoring a 'strict vegetarian diet' because of the 'morbid nature' of the 'alkaloids of putrefaction' which 'every piece of animal flesh is saturated with." "Peter D'Adamo, N.D. has recently published a popular book in which he encourages a diet based on his interpretation of the ABO blood groups and health. This blood type diet theory encourages daily consumption of animal flesh by people of blood type O and blood type B. Together these two blood types make up between 56% and 69% of population of the United States. Schools of naturopathic medicine have begun to include this theory in their curriculum and our colleagues often recommend a diet including daily consumption of animal flesh to vegan/vegetarian patients of blood type O or B." The foods we eat contain lectins. Because of how lectins clump (or "agglutinate") other molecules they have the capacity to create health problems for human beings. Botulism toxin has a lectin, ricin, that is so deadly you would never encourage someone to consume it." "Also (regarding lectins), there is evidence that enzymes such as intestinal transglutaminase, secreted in response to certain lectins, repair lectin-induced damages to the microvilli and gut epithelium In so doing these enzymes would inhibit and occasionally eliminate the potential for the chronic intestinal inflammation, bacterial overgrowth and illness ascribed to eating "wrong" for your blood type." | ||||||||||||||||||
Response | Much of Dr. McMahon's criticism suffers from the fallacy of argument from incredulity (sometimes called "argument from ignorance") and the fallacy of argument by appeal to fear and emotions. Both Henry Lindlahr and Benedict Lust died in their early 60's. A recent study of 1200 people who reached the century mark between 1932 and 1952 showed only four were vegetarians. At some point in time, naturopathic medicine, and in some peoples' minds health itself, became strongly associated with a vegetarian diet. Some individuals within my own profession suggest that I had abandoned the core of naturopathic medicine by advocating good quality meat for individuals of certain blood types. Getting stuck in a belief system can be a tough place to dwell. Often a good question to ask is, "what does the evidence show?" Naturopathic medicine developed from the water cure movement of Europe. Theodor Hahn is credited as being the first of the pioneers of this water cure movement to integrate vegetarian dietetic principles. He was convinced that a meat-free diet would prolong life. In fact he was so convinced of the value of a vegetarian diet that he spent a great deal of his professional life writing books and pamphlets on the subject and was the editor of a magazine called The Vegetarian. He died of colon cancer at the age of 59. Perhaps his diet some how extended his life and he would have died at an even younger age had he not been a vegetarian. This at least is a quite common argument I have heard repeated by supporters of a vegetarian diet when one of their proponents dies an early death. Ultimately there is no answer, but it is ironic that the person responsible for integrating a vegetarian diet into what would become naturopathic medicine died so young of colon cancer. According to Drs. McMahon and Williams, Henry Lindlahr, the founder of "Scientific Naturopathy" in the United States, "was completely committed to vegetarian diet." Actually, the opposite is true. In fact it has been stated that Lindlahr often incurred the wrath of militant vegetarians by suggesting that "properly prepared and combined vegetables and meats could be more wholesome than certain bad vegetarian combinations." He wrote that it was not his intention "to make a fetish of vegetarianism." Clearly he was not the strict proponent of this diet that these critics would like to believe. Dr. D'Adamo is far from the only naturopath advocating a hunter gatherer-type diet for some people. The work of Dr. Ron Schmid, ND in his books Native Nutrition and Traditional Foods Are Your Best Medicine constitute some of the best writings by an ND on the subject. There may be a repair mechanism that helps heal the intestinal lining from lectin damage, but that does not constitute an effective argument for their wholesale consumption. Put another way, our skin would also eventually heal if we sliced it open with a kitchen knife, but that is not a good reason to cut yourself. Is it too much to expect a critic with an agenda to be possess a rudimentary level of knowledge in the field they purport to criticize?
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3. | |||||||||||||||||||
Title | Wikipedia: The Blood Type Diet | ||||||||||||||||||
Link | Link (HTML) | ||||||||||||||||||
Authors | Multiple Authors (Open Source Encyclopedia) | ||||||||||||||||||
Distribution | Wikipedia; entries enjoy high rank with Google search engine. | ||||||||||||||||||
Author Qualifications | Anybody can add, delete and edit entries on Wikipedia. In general, this leads to fairly high quality content, especially in areas which do not reflect 'pop culture,' such as biochemistry and information technology. However when viewed by experts in their chosen areas, the quality of the work is often found lacking. A quick view of a few entries on subjects of general public interest will soon disclose, that some individuals tend to take things to a very personal level. Vandalism is also common on Wikipedia. Often a good idea of the current tone of a Wikipedia article can be gleaned from viewing the talk page for the entry. | ||||||||||||||||||
Criticism Type | Well-poisoning (opponents of alternative medicine; naturopathic medicine) | ||||||||||||||||||
Article Synopsis | It is very hard to provide relevant quotes from the Wikipedia page on the Blood Type Diet since the entry changes on an almost weekly basis. There is a tendency to highlight negative articles and links about the Blood Type Diet while removing articles and links supportive of the theory and using insider editor privileges to lock or block editing. Many of the negative entries are written by special interest groups ('rational skeptics', 'guerilla skeptics') who are self-admittedly opposed to any form of alternative medicine or scientific theories. A clear sign of just how unreliable Wikipedia can be is the fact that the lead paragraph for what should ostensibly be an important entry on 'lectins' references 'Krispin's Lectin Story' a webpage compiled by a non-scientist entirely from third party sources that, rather incredulously, claims that the blood type diets 'are high lectin diets.'[retrieved 3/9/2012] A main statement claims that "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 dieticians, physicians, and scientists is that the theory is unsupported by scientific evidence." provides links to external sources that are unrefereed, arbitrary comments, or opinion pieces. This fallacy is known as argument from authority, i.e "since certain selected experts disagree with the blood type diet theory, it must be wrong." Extensive wordage is devoted to discrediting the theory (expounded in the most simplest of terms in Eat Right for Your Type) that different blood types appear to have developed their unique digestive strengths and weaknesses due to an adaptation over time to changes in the human food supply. In its most basic form, the theory posits that type Os may have developed their ability to metabolize and thrive on animal protein due to their being the most common blood group at the time humans were transitioning from a scavenger type type to a more hunter-gatherer diet. For years this was thought to run counter to conventional molecular genomics, due to the fact that blood type A is thought to be the so-called 'wild-type,' and that the mutations that resulted in different ABO blood types were in fact millions of years old. However a recent study in the journal Molecular Biology and Evolution indicates that: 'Previous studies indicated that B and O alleles were derived from A allele in human lineage. In this study, we conducted a phylogenetic network analysis using six representative haplotypes: A101, A201, B101, O01, O02, and O09. The result indicated that the A allele, possibly once extinct in the human lineage a long time ago, was resurrected by a recombination between B and O alleles less than 300,000 years ago.' Paradoxically, the prior findings of the lead author of this article were the original citations used to refute Dr. D'Adamo's theory. The Wikipedia design format does not typically work well with controversial topics. Typically, the victory goes to the most obsessed, which are almost always the skeptics. Walling off evidence that you find inconvenient to your world view is not how you discover the truth. The editors at Wikipedia are entitled to their opinions, but let's not confuse that with presenting factual evidence to the contrary. | ||||||||||||||||||
Response | The entry on the blood type diet, as with most entries on alternative medicine, are quickly stamped and categorized as 'pseudoscience.' This is a highly pejorative accusation, implying the lack of a sound scientific basis. Classifying the blood type diet as pseudoscience is not only intellectually dishonest, it violates Wikipedia's own definition of pseudoscience. Citations attempting to support the assertions of the editors that the diet has been 'discredited' have, at various times, included blogs and websites with no other justification than the author's particular opinions. Wikipedia needs to be reminded that a scientist with an opinion is not a scientific opinion. Another example of Wikipedia's selective inclusion policy stems from arguments about the genetics and anthropology of the blood types: Luiz C. de Mattos and Haroldo W. Moreira point out that assertions made by proponents of blood type diets that the O blood type was the first human blood type requires that the O gene have evolved before the A and B genes in the ABO locus; phylogenetic networks of human and non-human ABO alleles show that the A gene was the first to evolve. They argue that it would be extraordinary, from the perspective of evolution, for normal genes (those for types A and B to have evolved from abnormal genes (for type O). Fair enough. In molecular history, type A appears to be the 'oldest' blood type, in the sense that the mutations that gave rise to types O and B appear to stem from it. Geneticists call this the wild-type or ancestral allele. The type B mutation is a simple replacement of one of the letters of DNA in the ABO gene with another; what geneticists call a snp (single nucleotide polymorphism) and everyone pronounces as 'snip.' The type O mutation is much more fascinating: It resulted from the complete loss of a letter in the ABO DNA and, like on a train when a boxcar is removed, all the other cars just move up by one. This type of mutation is called a frame shift and perhaps most amazingly, virtually every other known frame shift mutation is highly lethal. However, if you are type O, it made you. However, although Type A is the genetic ancestor, it appears to have disappeared in humans a very long time ago, and then 'resurrected' itself about 300,000 years ago. This would be in accordance with the demographic evidence and would support a theory that hypothesized a more significant earlier presence for type O. (REF: Kitano T1, Blancher A, Saitou N. The functional A allele was resurrected via recombination in the human ABO blood group gene.Mol Biol Evol. 2012 Jul;29(7):1791-6]) | ||||||||||||||||||
Notes | Dr. D'Adamo spent most of 2007 getting his biographic entry removed from Wikipedia as it was an almost constant source of slander and innuendo. Sadly, Wikipedia has no clearcut policy to handle entries about live persons who oppose their inclusion. This was finally resolved by in a rather left-handed manner by lobbying to convince the Wikipedia administrators that Dr. D'Adamo was not a 'noteworthy person suitable for inclusion.' | ||||||||||||||||||
4. | |||||||||||||||||||
Title | The Blood Type Diet: Fact or Fiction? | ||||||||||||||||||
Link | Link (HTML) | ||||||||||||||||||
Authors | Michael Klaper, Michael, MD (Hawaii, USA) | ||||||||||||||||||
Distribution | Extensively cross-posted throughout the internet, principally on vegan websites | ||||||||||||||||||
Author Qualifications | The author is a medical doctor. Dr. Klaper has not authored any peer-reviewed scientific papers on blood groups or lectins. He has published several books on vegan nutrition, principally for children. | ||||||||||||||||||
Criticism Type | Opposing diet theory (veganism) | ||||||||||||||||||
Article Synopsis | "One of Eat Right For Your Type's most disturbing characteristics is the frightening images that the author calls forth without providing scientific documentation. For example, D'Adamo hangs much of his theory on the action of lectins, proteins found on the surface of certain foods that can cause various molecules and some types of cells to stick together. He blames lectins for serious disruptions throughout the body, from agglutination of the blood cells to cirrhosis and kidney failure (page 24). He even scares the reader about these lectin "boogie men" with the tale of ex-KGB agent Georgie Markov who was murdered with an injection of the ultra-potent lectin, ricin. To begin to convince me of the existence of his “lectin gremlins,” he would have to publish photographs, taken through a microscope, of muscle tissue biopsied from people with Type O, Type A, Type B, and Type AB blood after they have eaten kidney beans and/or lentils. The photographs should clearly show the lectin deposits in the muscles of people with Type O blood - and not in the tissue samples from the muscles of people with Type A blood. Remember, there is nothing sacrosanct about the ABO blood typing system devised by Dr. Landsteiner in the 1920's. It is only one system classifying more than thirty proteins on the surface of cells that determine other blood groups, with names like Auberger, Diego, Duffy, I, Kell, Kidd, Lewis, Lutheran, MNSs, P, Rh, Sutter, and Xg. This means that food selections that may be "right" for the ABO blood group system might be "dead wrong" for someone's Kell or Kidd antigens. Why are we deifying the D-galactosamine-fucose molecules on the red cell surfaces that determine ABO Type? " | ||||||||||||||||||
Response | Dr. Klaper's review features two basic logical fallacies: argument from incredulity or ignorance and argument by appeal to fear and emotions. He may want to check his facts before he formulates his opinions. Lectins are not found on the surface of many foods. They are an integral component of the foods, principally found in grains, seeds and vegetable. The carbohydrates they attach to (including the blood type antigens) are on the surface of the cells of the body. The ricin tale were first described by DJ Freed MD, Head of Immunology at the University of Manchester Hospital in Great Britain, in the introduction to his chapter on lectins in Challcombe and Brostoff's textbook Food Allergy and Intolerance, and in his review article for the journal Lancet. It is common knowledge in the scientific community. Dr. Klaper accuses Dr. D'Adamo of scaring people with 'lectin gremlins' when right on the home page of his own website we have the following: "Every 30 seconds in this country, someone clutches their chest and has a heart attack," Klaper said. "Heart disease is the No. 1 cause of death in North America, and it's caused by atherosclerosis, which is that yellow greasy stuff. But heart disease is reversible, and that yellow greasy stuff will go away if you stop running animal fat through your body. A meat-centered diet, he said, also upsets the body's hormone levels and has been correlated to various forms of cancer." Dr. Klaper's standards of proof are equally two-faced: He would like to see muscle biopsies on lectin-munching test subjects, presumably type O carnivores engorged on whole wheat bagels. Any compassionate scientist could only be astounded by a silly paragraph such as this. Biopsies no less! Any volunteers? No research study review board would ever approve a study of this type. However, there are numerous studies on MEDLINE which document the systemic effects of dietary lectins. Dr. Klaper accuses Dr. D'Adamo of 'deifying' the ABO blood groups over the others. This is quite true, and there are numerous scientific reasons behind it. For one thing, the other systems don't manifest in the digestive tract, nor appear to genetically influence the production of digestive secretions. Only ABO is expressed outside the bloodstream, and in fact is quantitatively expressed in greater amounts in digestive mucous than on red blood cells. Here Dr. Klaper falls into the common trap of medical professionals: They are simply unaware of the broader significance of ABO blood type, as they were taught in school nothing more than its importance with regard to transfusion. Lansteiner discovered the blood groups in 1900, not the 1920's. | ||||||||||||||||||
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5. | |||||||||||||||||||
Title | Eat Right 4 Your Type Hype | ||||||||||||||||||
Link | Article (HTML) | ||||||||||||||||||
Authors | Sally Eauclaire Osborne (Santa Fe, NM) | ||||||||||||||||||
Distribution | The Weston Price Website, and a few low-carb diet websites | ||||||||||||||||||
Author Qualifications | Sally Eauclaire Osborne, MS, is currently completing requirements for the CCN (Certified Clinical Nutritionist) credential with the International and American Association of Clinical Nutritionists (IAACN). She has not authored any peer-reviewed scientific papers on blood groups, nutrition or lectins. | ||||||||||||||||||
Criticism Type | Opposing diet theory (paleolithic; low carb) | ||||||||||||||||||
Article Synopsis | "When we take a careful look at this theory it appears a bit "sticky." The majority of scientific studies linking blood types and lectins have involved lectins added to blood isolated in test tubes. But foods are NOT supposed to be injected directly into the blood stream. Mother Nature designed the digestive system to process them for safe transport through the bloodstream and for easy assimilation into our cells. A healthy body with full digestive and assimilative capabilities is completely capable of handling food lectins. In fact, this is borne out by numerous studies which suggest that lectins are either dismantled by enzymes -- which are abundantly present in raw and fermented foods - or by cooking, which destroys the helpful enzymes but compensates by denaturing complex proteins so that they can more easily be broken down during the rest of the digestive process. Few people today, however, can boast fully functioning digestive systems. Two health problems that have undoubtedly contributed to the ability of food lectins to slip uninvited into the bloodstream are: widespread hydrochloric acid (HCl) and trypsin deficiencies, which make it difficult for people to properly digest protein, and "leaky gut" syndrome, a condition in which large undigested or partially digested protein molecules "leak" out of the GI tract and into the bloodstream, where they do not belong and where they are likely to provoke an immune system response. Adelle Davis did not make a link between HCl deficiencies and blood type; and Dr. Atkins does not consider blood type when he tailors programs to his clients, according to Joel Pescatore, Ph.D., a nutritional counselor at the Atkins Center. So it is possible that most of the people with this problem are all Type As or ABs, the types Dr. D’Adamo feels are predisposed to chronic shortfalls of HCl. The people with ample HCl may all be Type Os, as Dr. D’Adamo claims. Yet the identification of age-related deficiencies coupled with reports of failing health suggest a gradual decline of HCl over time. If so, HCl deficiency is a preventable and correctable problem, regardless of blood type. The obvious conclusion is that proper soaking and cooking, and the use of gelatin, can make the blood-type diets irrelevant. Type Os find they can eat grains. Type A people -- whom Dr. D’Adamo believes are natural vegetarians because they typically lack the abundant secretions of HCl necessary for easy digestion of meats -- find meats easier to digest if they are served with a gelatin-based gravy, stewed in their own broth or served along with a cup of soup. And gelatin can alleviate the allergic reactions and sensitivities that numerous research studies have connected to blood Types B and AB. Follow these simple, old-fashioned rules and those pesky lectins will be dismantled in your healthy gut and never cause problems in the bloodstream. " | ||||||||||||||||||
Response | Like much of Dr. McMahon's criticism, Ms Osbourne's review suffers from the fallacy known as argument from incredulity (sometimes called "argument from ignorance"). In general Ms. Osborne seems quite new to most of the lectin material presented in the book, a fact that unfortunately does not inhibit her from writing about them. But don't take my word for it. Dr. D'Adamo has said this about Ms. Osbourne's review: 'Interestingly, a quick trip to the anti-soy website that Ms. Osbourne writes for brings up the interesting observation that one should not consume soy because of its dangerous hemagglutinating lectins. Now, it seems that when I write about lectins, Ms Osbourne states that they can't get in to the body. However when they can be used to support her assertion that soy is a bad food for everyone, they apparently can enter the body and do all sorts of harm.' Right after this advice, there follows a bizarre recommendation to use gelatin in your food to block the effect of 'those pesky lectins'. In addition to the fact that many people can not use gelatin for religious reasons, in over 6 years of research we have never seen a single study to support this contention. In fact many animal proteins, such as albumin, enhance the reactivity of lectins. This is a completely unsupportable statement, with no basis in either basic immunology or molecular biology. We only feel bad for those who read it and think it is rational enough to employ. After this paragraph, there follows a long section of her review which tries to explain why the blood type diet works, although in the beginning of her article Ms. Osbourne claims she is one of several nutritionists who see "little or nothing that clinically or scientifically supports the theory." Again, there follows a long section of dietary advice with no particular relevancy to blood type at all. The section talking about Adelle Davis and Robert Atkins makes even less sense. Adelle Davis did not research blood groups. The head nurse at the Atkins Center has in the past gone on record as stating that they did have problems getting the diet to work with blood type A individuals. | ||||||||||||||||||
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