On Tue, 5 Aug 1997, John C. Pavao wrote:

> I have to take issue with the assumption that eating meat causes cancer
> based on studies done on modern peoples eating modern diets.  Does a
> non-meat eating person who starts eating meat raise his/her cancer risk
> "substantially", or do people studied who already were eating meat have a
> higher risk than those who were not?  What other variables were involved?
>  What did their diets look like overall?  Were there other risk factors
> that might have separated the two groups?

I'm not assuming any such thing.  I'm *asking* what might be the
reason for the apparently robust correlation between red meat
intake and colon cancer.  Your questions are all reasonable ones
to ask.

> How
> much stock can we put in any study of the health effects of a particular
>  food on the human physiology when the subjects of the study are eating
> artificial foods which are filled with chemicals and carcinogens and which
> are refined to the point that many are stripped of any intrinsic
> nutritional value?

But the question remains:  If these other things are causing
cancer, then why does the cancer risk correlate with red meat
consumption?

As I mentioned in a previous message concerning carotenoids, it
is certainly possible that the presence or absence of something
else in our typical "civilized" diet makes us vulnerable to
something carcinogenic in red meat that otherwise would not
bother us.

Or it may be that the sort of red meat that we eat, or the way in
which we eat it, is sufficiently different to cause trouble.

Or, as Muriel suggested, it could be that other aspects of
civilization  (our aversion to bleeding?) that are the problem.

While I share your general, and healthy, skepticism about these
kinds of studies, I wouldn't go so far as to conclude that they
should be disregarded.

Now here's another citation: M. Anti, Effect of omega-3 fatty
acids on rectal mucosal cell proliferation in subjects at risk
for colon cancer.  Gastroenterology 1992; 103; 883-891.  This one
shows that n-3 fats decrease the risk.  Aha!  Yet another datum
pointing to the importance of n-3 fats, conspicuously absent from
domestic meats.

Do we see a pattern here?  Many recent studies documenting the
"protective effect" of n-3 and monounsaturated fats are now
recognized as showing that if these fats are present in
sufficient quantities, the allegedly "bad" saturated fats are not
a problem.  This is mainly for heart disease, but now we see
similar evidence regarding colorectal cancer.  And we know from
anthropological and zoological sources that the meat of wild
animals is richer in n-3 fats, and that hunter/gatherers eat
animal monounsaturates that we tend to ignore: marrow, eye socket
fat, etc.

My tentative conclusion: The importance of n-3 and
monounsaturated fats is only beginning to be recognized, but
these will turn out to have far-reaching effects.  If olive oil
and fish oil are the main sources of these available to modern
people, or acceptable to them, then to ignore these sources is
potentially perilous.

Todd Moody
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PS  I heard about the death of that 122 year-old woman this
morning.  They mentioned that her preferred diet was rich in
chocolate and olive oil.