> Date:    Wed, 23 Sep 1998 17:22:28 -0400
> From:    Ruediger Hoeflechner <[log in to unmask]>
> Subject: Eat right for your type
>
> O One of the strangest diet books of the last years is Peter D'Adamos "Eat
> right for your type". D'Adamo tries to explain his blood group specific
> dietary recommendations with human adaptations to different environments
> (O: oldest human blood group/hunter-gatheres, A: adaptation to
> agriculture/vegetarianism/caucasian, B:adaptation to colder
> climates/dairy/mongoloid).
>
> I believe it's necessary to state clearly: D'Adamo's diet has nothing to do
> with the topic of paleolithic nutrition. Without doubt - there are a lot of
> documented links between blood type and risk of various diseases. I also
> don't question the possibility of immunological reactions between blood
> group antigens and certain foods. But until now there is no scientific
> basis for the conclusion, that each blood type requires its own diet.
> D'Adamo has blown up a mouse to an (bestselling) elephant without showing
> any new data. And his basic assumptions are simply wrong.

D'Adamo's diet program is actually based on several loosely
connected theories.  One is that, although the blood type alleles
may have been present forever, the different types didn't
flourish until certain historical epochs.  He explains this as a
consequence of the fact that different foods agglutinate blood
cells of different typies.  Another theory has to do with
metabolic types and diet.  He claims that type As, for example,
produce the least amounts of gastric acid and intestinal alkaline
phosphatase.  This supposedly makes it harder for them to digest
meats and animal fats.  Yet another theory is that lectin-caused
hemagglutination is linked to particular diseases and health
issues.  Unlike other blood types, ABO types are not a "true"
blood type.  That is, the type is not limited to blood cells but
includes other cells as well, such as cells of the intestinal
lining.

Put it all together and you get a diet book.  Speaking as a
layman, I have the impression that the specific interactions of
lectins with various tissue types is something well worth
exploring, and may well have implications for the history of
major dietary transitions.  When lentils were introduced into the
food supply, for example, there may have been a sudden and strong
selection pressure against type Os, whose cells are supposedly
agglutinated by lentil lectin.  Type As would have done much
better.  But the hypothesis needs a lot more confirmation, in my
opinion.

I suspect the metabolic type theory goes nowhere.

I await more informed opinions with interest.
(Rather, I await with interest more informed opinions.)

Todd Moody
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