On Thu, 25 Nov 1999, Ben Balzer wrote:

> Unfortunately D'Adamo's on leave from his site finishing his 4 th edition.
> His diet is based on eliminating lectins, a sentiment that I agree with -
> but he then recommends soy products which are loaded with
> lectins!!!!!!!!!!!!!!!!! Please explain.

You have it wrong.  ER4YT is not based on on eliminating lectins,
which is in any case impossible.  It is based on the premise that
the *effect* of specific lectins on the body is a function of
blood type.  This is because lectins are *hemagglutinins* and
because the ABO blood types are not "pure" blood types.  That
means that tissues other than blood have ABO properties --
notably the lining of the intestines.

The *theory* behind the lectin part of ER4YT is impeccable.  If
and when lectins enter the bloodstream (and D'Adamo is able to
present sufficient evidence that some do), they either cause the
blood to agglutinate or they don't.  If they do, then the
agglutinated blood cells attract macrophages, an immune response.
They can also "target" the tissues of specific organs, by means
of molecular mimicry, causing an auto-immune response.  He goes
on to argue that certain lectins are actually beneficial for
certain blood types because, for example, they "mimic" cancer
cells, thus *helping* the body to get rid of these, by
stimulating the immune system to attack them.  Thus, he argues
that the apparent protective effect of soy against certain
cancers (e.g., prostate cancer) is a result of a soy lectin that
resembles the particular cancer cell closely enough that the
agglutinating action of the lectin triggers an assault against
the cancer.

So, in D'Adamo's view lectins cannot be regarded as good or bad
in themselves, but only in light of their immunologic effects on
the body, which depend to a significant extent on ABO blood type
because these effects are a result of their hemagglutinating
properties.

On the critical side is the fact that D'Adamo is generally unable
to give a specific account of how particular lectins are linked
to particular health issues.  In this his theory is no worse off
than the "foreign protein" theory of Neanderthin, but it's still
an issue, because theories this vague are hard to put to the
test.  Worse, D'Adamo mixes his lectin theory with a "metabolic
type" theory that has nothing to do with lectins, but is based on
other metabolic differences between the ABO groups.  For example,
type As supposedly secrete less gastric acid (true?) and less
intestinal phosphatase (I gather this one is well established)
than type Os.  D'Adamo thinks this means that they are less
equipped for digesting animal protein.  I am not convinced that
he has a good case for this claim.

One thing that D'Adamo does do, however, is collect evidence that
certain diseases (notably "diseases of civilization") are not
impartial with respect to ABO blood type, but favor certain types
over others.  This evidence, some of which has been kicking
around for decades, does indeed suggest that he is on to
something.  There is no obvious reason why coronary heart disease
and certain cancers should prefer type A blood, but there is
unmistakable statistical evidence that they do.

I have beat my head against this one for a while, but I can't
really say that I have a clue as to what might be going on with
this.

Todd Moody
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