On Wed, 11 Oct 2000, Mary Craddock wrote:

> Todd,
> Speaking of a diet dominated by meat...I read yesterday that a study done by
> a cancer research group(don't have specifics with me) said that people that
> eat red meat 7 times a week or more have significant increases in the risk of
> cancers of the digestive system...colon, rectal, etc.
> This was a blurb in a natural health type magazine.
> Is there an increased risk just from the meat itself or because of what is
> eaten along with the meat? Is it because of the chemical changes that occur
> in cooked meat?
> They did not go in to details...only said that meat that is cooked at high
> temps is carcinogenic.
> I try not to be concerned when I read these kinds of things, but they linger
> in my mind. Can you or anyone shed some light on this concern?

I wish I could.  It is a fact that a number of epidemiological
studies have found a strong correlation between red meat
consumption and colorectal cancer.  At least one study has failed
to find such a correlation, however.  Even Bruce Ames, the
scientist that Ray likes to cite when he is casting aspersions
against peanuts and the like, takes this very seriously, as does
Walter Willett, one of the best-known epidemiologists in the
world.  Still, while I don't take quite as dim a view of
epidemiological conclusions as Ken Stuart does, I do agree that
they are far from giving us the whole story.

Obviously, if meat consumption is itself correlated with some
other factor, then that factor too will be correlated with
colorectal cancer, and the task is to figure out whether it is
the meat or that other factor that is causing the colorectal
cancer (if either is).  Epidemiologists know this and try to
control for it, by multivariate analysis.  But they can only
control so many variables.  We don't know if it's the meat
itself, the cooking of it, or something else -- or whether the
whole thing is a statistical illusion.

But it lingers in my mind too, especially since my mother had
colon cancer not long ago.

Todd Moody
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