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The Uninformed Skeptic: Eat Right For Your Type January 28, 2009

Posted by oktyabr in consumer, health, it's debatable!, opinions, personal, skeptic.
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It was one of those occasions when a relatively large group of my extended family gathered together in a public establishment for an  extended period of time, in this case, a fairly popular restaurant.  The menu was extensive and offered many appetizing choices and I mulled my decision for quite awhile with a growing amount of impatience and suggestions from parent and sibling alike.  One suggestion suddenly stuck out from the rest:  “You shouldn’t eat that… you have the same blood type as me.” That’s how the argument started…

It turns out that a certain book had been circulating through members of my family, as is known to happen time to time with a large group of “readers”, called “Eat Right 4 (For) Your Type” by a Dr. Peter D’Adamo who holds a doctorate in something called “Naturopathic Medicine“, something I could write an entire article about (maybe for another time!), that has apparently been on some best seller lists for several years…

I contemplated some expensive, high calorie dishes that I normally wouldn’t be contemplating (or at least certainly wouldn’t make for myself at home) and vocalized my consideration out loud, in no small part to help reassure the rest of my family that I was, indeed, making a decision, when one of my siblings exclaimed “You shouldn’t eat that!  You have the same blood type as me.”


My family, or at least the members that had read the aforementioned book, quickly filled me in.  The premise of the book, and of his website, related writings, and whole slew of other “blood type diet” paraphernalia, is that while we are all human we have one characteristic that divides us in important ways… our blood type.  Specifically that our blood type strongly suggests what sorts of things we should be eating to obtain (and presumably retain) optimum health.  Let me make that clear: The premise isn’t that eating certain foods is good for you, that’s the premise of pretty much any nutritionally healthy diet!  The premise is that eating very certain foods, or types of foods, is good for YOU, the individual, and furthermore that your particular diet is based on your specific blood type which was decided many generations and possibly tens of thousands of years ago, genetically.

Now this theory also works as a two way street and is one of my biggest arguments against such a idea.  If you believe in general evolutionary theory (survival of the fittest, form defined by environment, etc.) *everything* that can be singled out and categorized about a species of animal exists the way it does for a reason (whether we know that reason is something else entirely), whether current such as a fish’s gills to breath underwater, or antiquated such as human wisdom teeth and body hair which are evolutionary leftovers that we are thought to be slowly “outgrowing”.

Now if a human blood type defines what we should eat, shouldn’t the converse also be true?  That from an evolutionary viewpoint it may also be said that the kinds of food “we” eat, as a family tree spanning many, many generations, should also be a major factor in our blood type?  Then why would family members have different blood types?  Why is it even possible that a mother may (and often do) carry a child of a different “blood type” than her own?

DISCLAIMER: Hey, I called this post (and ones like it, to come in the future) “The Uninformed Skeptic” because while I am skeptical I do not believe I have all of the answers!  While I am a jack of all trades, of a sort, I have no formal education in medicine, biology or nutrition so why should my logic be taken at any more than face value?  None the less I think my logic is sound and I would love to be informed otherwise.

That said let me show you, my dear readers, that I’m not entirely ignorant either!

From wikipedia:

A blood type (also called a blood group) is a classification of blood based on the presence or absence of inherited antigenic substances on the surface of red blood cells (RBCs). These antigens may be proteins, carbohydrates, glycoproteins, or glycolipids, depending on the blood group system, and some of these antigens are also present on the surface of other types of cells of various tissues. Several of these red blood cell surface antigens, that stem from one allele (or very closely linked genes), collectively form a blood group system.[1]

Much, much more information is available in great detail but I get the gist of it…  Ok, so “blood types” are classifications of groups of individuals based on the presence of certain antigens on the surface of red blood cells that are indicative of the likely-hood of a negative reaction to blood infusion from a different blood “type”.  In reality there are now recognized 30 different “blood type systems”, the “ABO” the most common in regards to blood transfusion compatibility and the one at the crux of Dr. D’Amado’s premise expressed in his books.

Some antigens describing in part an individual’s “blood type” are, in theory, established early on:  “After birth an infant gut becomes colonized with normal flora which express these A-like and B-like antigens, causing the immune system to make antibodies to those antigens that the red cells do not possess.”  They are established through sensitisation to the environment, i.e., the air, the water, bacteria found in both, and in the foods that are eaten.

Stranger facts abound such as most bone marrow transplant patients, given marrow of a different blood type, will eventually adopt that foreign blood type.  This is of course in part due to that the bone marrow is responsible for the production of new red blood cells but would also imply something different… that blood types are an indicator of compatibility, not an absolute, for if bone marrow of different blood types can be exchanged then so should blood?  My gut instinct (without reading more in depth medical definitions) is that yes, they are, given enough proper preparation.  “ABO” blood types are defined for use in an emergency transfusion but are no absolute indicator by themselves of success or failure.  Many other factors including the other 29 different blood type systems can play a role in this ultimate equation.

So back to topic…  determining your optimum diet from your ABO blood type?  I find this doubtful as your blood type is not only defined by what you are exposed to early on in infancy but also your parents blood types that were, in turn, also influenced by what they were exposed to and so on.  Furthermore while the ABO blood type system exists because of said groupings of antigens it likely did not exist in the form we understand it today millions or even tens of thousands of years ago, at least if it was possible to trace back a specific family tree.  Crazy?  Maybe…

Differentiation of any component as significant as the ABO blood type system, described by encompassing a large group of individuals over a great length of time, happens as any evolutionary differentiation does, through isolation.  Whether you believe in Adam or Eve or Darwin’s natural selection and anthropogenesis (the study of human evolution), it seems likely that the species of human we are most familiar with today were once much fewer in number and isolated to a very small niche of the world.  It is likely that at this time, being all “related” to each other closely in the genetic sense, not the familial way, (much more closely than any two random individuals are today), that there was no causation for a sophisticated blood type system as described by the ABO system in question.  In part I believe that different blood types formed as the human species spread to the different corners of the world, each with their own ecological differences, and for a multitude of reasons had very limited contact (and opportunities to extensively interbreed) with groups from other parts of the world.  This, I believe, took time on a scale of millions of years.  It’s only in relatively recent history (the last few thousand years), as civilization has recombined, have our blood types as a species become something that may be classified on a global scale.

Census of ABO blood type distribution taken world wide would seem to at least in part confirm this…  Click for reference.  For the most part we find a roughly even distribution of blood types globaly with a few stand-out anomalies and although the specific chart does not go into detail I would be most curious to know the blood type distribution of aboriginal peoples such as the “native American Indian”, the Australian Aboriginies and the Inuit people, all of whom have very different and exclusive diets and may be found to have genetic trees left mostly intact in this otherwise homogeneous world.

What does this have to do with diet?  In my opinion, not a hell of a lot, but it made for an interesting read.

Back to the dinner table!  After being advised that my blood type suggested I should be eating much more plant material I ordered the largest beef steak on the menu, medium rare, and the debate continued…

I like to classify ideas in a roughly scientific manner and believe that many questions can be explored and sometimes answered, perhaps correctly, simply through logical deduction.   General evolutionary theory is in particular a great playground for such thought and these are the tools that I used in the debate at our table:

  • We are omnivorous creatures of opportunity meaning we eat that which is readily available, plant or meat.
  • We are descended from carnivores.  Canine teeth and binocular vision were evolved for hunting and eating meat, not vegetables.
  • We have evolved a large brain/mass ratio, something very expensive in evolutionary terms, and possible only through a diet made up primarily of complex proteins and a high caloric value, especially in very ancient times when we lived mostly “hand to mouth”.
  • The development and optimal maintenance of such a brain even today still requires an intake of complex proteins and amino acids that are still most easily obtained by eating meat, at least in the western world.

If these things are found to be at least mostly true then why would we be now, today, at a point where a diet not defined by evolution be a highly significant factor in our overall health and well being?  For those of you that view evolutionary theory as all smoke and mirrors does your alternative belief system have any reason or evidence that we, as human beings, should eat different things based on a few antigens?  I didn’t think so.  🙂

As a footnote to dwell on the next time you are at the dinner table…  cats, felines in general, a decidedly carnivorous (meat eating) sort of animal, has three different blood types (type “A” is by far the most common in domestic house cats found in North America).  Dogs, canines in general, also carnivores, have no fewer than THIRTEEN different blood types and horses, a decidedly herbivorous (does NOT eat meat) animal, has eight.  Go figure…

I was asked if I had actually ever read the book and the answer is, no.  I have however leafed through it trying to absorb the generalities without the specifics so I haven’t actually tried to present an actual review of this book here.  I’ll leave that up to a real Ph.D to do for me: from quackwatch.org



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