On Mon, 29 Nov 1999, Wally Day wrote:

> I have a couple of questions regarding "foreign"
> proteins.

So do I.

> First, I was under the impression that proteins are
> "disassembled" by our digestive tract into various
> amino acids, which are then assimilated and utilized
> by the body for repair, etc.. If this is true, then
> how do "foreign" proteins have an adverse effect?

The premise is that some proteins have an adverse effect *before*
they are disassembled, and/or some proteins are never in fact
completely broken down to aminos. When there is an actual food
allergy, the protein is causing it before it is digested, just by
contact with cells in the digestive tract. But for various
reasons, other proteins resist complete proteolysis and thus
leave polypeptide residues, and these cause the mischief.
Lectins apparently fall into the latter category, since some of
them are resistant to the digestive enzymes.

> Along the same lines, why would there be a problem
> with eating grain fed vs. free range animals (besides
> the obvious higher fat content)? How could the adverse
> effect of foreign proteins possibly be transmitted to
> us through a grain fed animal?

This is a tougher one.  It is *possible*, I suppose, that if an
animal is grain-fed, some of the grain protein is not fully
digested, leaving residues, as described above.  And it is
*possible* that some of those residues enter the animals blood
and remain there, so that when the animal is slaughtered, the
blood still remaining in its tissues contains those polypeptides,
which we eat when we consume the meat.  As I say, this scenario
is possible in theory, but I don't know of any empirical
confirmation of it.  That is, I don't know of any study that has
found traces of grain proteins in meat.

Todd Moody
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