Eating for your type: |
Review of D'Adamo's
The Nutrition Practitioner, 2:1, 47-49, Feb 2000.
By Simon Martin, BSc (Hons), FSMT, LCSP (Phys), ANLP
Every system of medicine worth its salt has found a way of 'typing' to enable practitioners to make an educated guess at what type of diet, lifestyle and environment might be best for their patients.
All the traditional systems such as Ayurveda, Traditional Chinese Medicine and Tibetan Medicine have their ways. Modern nutritional therapy is moving steadily away from subjective methods towards measurements based on knowledge of medical science. The "Holy Grail" is a simple, accurate, reproducible test that will deliver, at low cost, a complete read-out of a patient's unique biochemical and physiological profile.
In the rush to go high-tech, a simple typing method has been overlooked. Naturopathic physician Peter D'Adamo has pioneered the use of blood type as a window on genetic make-up. The literature reveals a surprisingly large amount of research on the association between blood type and specific diseases. However, orthodox medicine assumes that the main importance of blood type is in transfusion; textbooks admit only two associations - type O and ulcers and type A with gastric cancer. In fact, even a most conservative reading of published research supports the view that type As appear to be more susceptible to many cancers, including breast cancer, as well as heart disease; type Bs to infections; and type Os to gastric cancer.
The link between blood type and disease is only part of the story. D'Adamo recommends eating foods that suit blood type. As discussed in the last issue, a little-known fact is that most foods contain naturally-occurring toxins called lectins which have the ability to agglutinate cells . This can have dramatic effects, including digestive disturbances, difficulties in absorbing nutrients and damage to the gut wall. Lectins can survive cooking and digestion and are able to get out of the digestive tract and into the bloodstream. Although many lectins are destroyed by cooking, some, such as those in wheat, carrot, maize and bananas for example, may have enhanced effects because of it. One of the first to be discovered and studied was Wheat Germ Agglutinate, which is known to pass into the blood and into the brain, despite the physiological blood-brain barrier. Many lectins resist digestion in the stomach and get into the small intestine, where they can inactivate enzymes used to digest protein. Gluten lectins may be involved in coeliac disease . The key point is that lectins are blood-type specific.
Blood type is a marker for basic internal chemistry. There are hundreds of ways to type blood, but D'Adamo suggests that the four basic blood groups (O, A, B, AB) provide about 90 per cent of the information needed to individualise a patient's diet. Further testing (such as for Mn group and secretor status), can fine tune this information. Rhesus status (negative or positive) is not significant at this level.
D'Adamo's research has shown that each blood group has foods that are highly beneficial, acting for that blood group almost like medicines, and foods that are likely be unhelpful. Blood types may have evolved in response to environmental factors, including the food supply available at the time. Current theories suggest that the basic blood types evolved chronologically in the order O, A, B, AB; these correspond to changes in the food supply experienced by hunter-gatherers, settler-agriculturalists, nomadic herdspeople and the modern, rather enigmatic AB "blend". A food's rating is decided both by its lectin content and also by its potential impact on a particular type's susceptibility to disease. This research gives nutritional therapists the ability to make scientifically objective dietary recommendations based on the physiology of the patient, rather on intellectually-constructed dietary models or the latest fad.
Why is blood type important?
There are two main reasons why a food may be beneficial - or harmful - to a particular blood type: physiology and facilitation.
Blood type is a marker for genetic endowment. In other words, with blood type come specific strengths and weaknesses. These are tendencies or probabilities - individuals may vary. There is evidence for them in epidemiological data and also from studies looking at their consequences.
As examples, type Os have a tendency towards higher levels of HCl than other blood types, while type As tend to have higher serum cholesterol.
This increased acidity appears to give Os the benefit of being able to more easily digest animal protein, which fits with the picture of Os as the hunter-gatherer type for whom a diet slightly higher in protein can be beneficial.
The drawback is that type Os are more susceptible to gastric ulcers. This observation was first published in the 1950s and, although still surviving in medical textbooks, does not appear to be given any clinical significance in modern orthodox medical practice. Intriguingly, the type O-ulcer connection has survived decades of changing theories about the prime cause of gastric ulcers. This has varied from over-production of HCl to stress (possibly causing more HCl), to the more recent proof that ulcers are "caused" by an overgrowth of the bacterium Helicobacter pylori . Discussions about the importance of the internal terrain aside, it has been established that the fucose in the type O glycoprotein cell "markers" (blood group antigens, or BGAs) makes it easier for H.pylori to attach to cells of type O than other types . Research has also now shown that even in familial gastric cancer - thought at one point to be due solely to genetic factors - H.pylori plays a critical role [4,5].
Type A's (and AB's) tendency to heart disease is well-established in the literature, following surveys of heart surgery patients [6, 7, 8]. Type A is associated with higher serum cholesterol than other types , Whincup, op cit. But as with type O, new evidence of the basic physiology of type A offers other explanations for the association even as cholesterol is challenged by factors such as oxidation and homocysteine as prime suspect in cardiovascular disease. The most significant finding may be that type As have a tendency to low levels of intestinal alkaline phospatase, an enzyme involved in the digestion of fat. Different blood groups appear to synthesise this enzyme at a different rate; the intestinal cells of type A bind almost all of the enzyme, whereas type Os and Bs have higher levels available for use in digestion [10, 11]. Type A and AB also have higher levels of factor VIII, predisposing them to clotting, and of the platelet "adhesive" von Willebrand factor  . This may give type As a tendency to thrombosis.
Facilitation describes the way in which certain BGAs make it easy for pathogens such as bacteria and viruses to attach to cells, such as H.pylori with type O cells, and to migrate between cells. This is also well-established in the literature (for a recent review see 14], and has fascinated researchers across many disciplines. As Mourant has described, an association between blood types and epidemic disease has enormous implications . Type Os are thought to be more vulnerable to Yersinia pestis, cause of the Black Death, the 14th Century's "millennium bug" which killed between 25 and 33% of Europe's population . Of more use to us, both A and A antigens offer receptor sites for Candida albicans , while type B and AB non-secretors have been found to be significantly more susceptible to recurrent urinary tract infections .
Other pathogens escape immune surveillance in certain blood types because they share antigens with the cells of their hosts [19, 20]. This is a significant problem with cancer. Hakomori was the first to hypothesise that immune systems of type A individuals may fail to recognise cancer cells with type A antigens . Research has shown that in some cancers, cell receptors may change to an A type; this has recently been demonstrated in breast cancer cells to such an extent that it may serve to predict lymph node involvement . No fewer than 7 different types of cancer have been associated with blood group A: gastric, breast, cervical, pancreatic, leukaemic, rectal and ovarian .
In an article of this length, it is impossible to give the full picture of the impact of blood group on health. D'Adamo's conclusions about the non-transfusion significance of blood type are routinely challenged. Critics tend to miss the point: D'Adamo has not invented this association, he has found it in the scientific and medical literature. What he has done is draw together research from many disciplines. The facts needed to draw even minor conclusions are spread throughout many different areas of science. Recent research,for example, has shown that the Pima Indians of the Gila River reservation in Arizona have what appears to be a genetic tendency to insulin resistance and have the highest rates of diabetes and diabetic-related disease and mortality in the world. I attempted to find out the Pima's blood type. Based on D'Adamo's work, it would surely be type O. Hunter-gatherers - even modern ones - do very badly on diets high in refined carbohydrates, particularly wheat, which is what the reservation Pima's live on. Wheat germ agglutinate is an insulin mimic, which adds to the picture. It is known that a separate group of Pima, who still live in the mountains, and eat a more traditional type O diet, do not have the same rates of diabetes - despite their genetic predisposition to insulin resistance. In order to confirm the Pima blood group, I contacted University of Arizona biochemists, biologists, anthropologists, evolutionary ecologists (all in separate departments), a grad student doing field research on diabetes and pregnancy with the Pima, the National Institutes of Health, and the US National Institute for Diabetes, Digestive and Kidney Disorders. Finally, a Native American health researcher at the University of Mexico referred me to the lead scientist of the NIDDKD's research centre on the reservation, who referred me to chart in a 1992 paper in the American Journal of Human Genetics. Yes, the Pima are type O.
The biggest mistake D'Adamo appears to have made is in having not run massive epidemiological studies to totally confirm the entire hypothesis before publishing consumer-orientated books. These books have further incensed critics because - at his publisher's request, it must be said - he has not referenced every sentence. I hope this article has shown that the research and the references are "out there". Blood type is a repeatable, objective method for identifying individual needs. ABO typing is simple, quick and cheap.
* Peter D'Adamo's two books are Eat Right for Your Type (ERFYT) and Cook Right for Your Type ( . Details of the basic types (see charts) are highly summarised from both these books.
His website is at www.dadamo.com
There is enough information in ERFYT to "do" the blood group diet, but the body of knowledge behind "beneficials" and "avoids" is dynamic and is continually updated.
* Simon Martin is the editor of CAM, the magazine for practitioners of complementary and alternative medicine. He has a degree in health sciences, specialising in complementary medicine, from the University of Westminster, and has studied nutrition and herbal medicine.
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