Day 017 - 25 Jul 94 - Page 49
1 "uncertainty factor". There is a mention of calcium in
this column. Can I just read the paragraph beginning "The
2 promoting effects of faecal bile acids". Do you have that
one?
3 A. Yes.
4 Q. It is after reference 45. "The promoting effects of
faecal bile acids are thought to be due to cytotoxic
5 injury leading to regeneration with accompany increased
cell turnover. Ionized fatty acids of dietary origin will
6 also irritate colonic epithelium; a high fat diet might
therefore be linked in a more direct way with colorectal
7 carcinogenesis. Similarly, dietary cholesterol has been
proposed as a direct tumour promoter. In the presence of
8 calcium ions the toxic effects of ionised fatty acids and
faecal bile acids would be abolished through their
9 conversion to insoluble calcium soaps. Abnormal patterns
of cellular proliferation in high risk individuals for
10 colorectal cancer disappeared when their diets were
supplemented with calcium carbonate." What conclusion
11 might we draw from that passage?
A. I think that his choice of words is very apt. For
12 example, he talks about the promoting effects of faecal
bile acids are thought to be due to cytotoxic injury.
13 What he is saying is that there are these theories which
have been put forward to try to explain why there might be
14 a relationship between bile acids, fat in the diet and the
possible causation of colorectal cancer. But what he is
15 saying is that we cannot go any further forward than
that. We have not the evidence to say there is a direct
16 causal relationship. These are purely theories which have
been put forward to try to explain what some people have
17 suggested is an effect.
18 Q. Does it follow from that that he is not suggesting that
the popular media should come out with headlines saying:
19 "Drink more milk and you will not get colorectal cancer"?
A. Well, I think the media have a lot to answer for in
20 the -----
21 Q. I am not going to ask you about that, not more the moment
at least. Can you just pass your eye across to the column
22 on the opposite side of the page where there is a
reference after reference 52 to selenium. Do you see
23 that?
A. Yes.
24
Q. Selenium a rare trace element reduces the incidence and
25 progression of cancer in animals exposed to carcinogens.
Low blood selenium levels have been correlated with a
26 reduced activity of glutathione"?
A. Yes, glutathione perioxidase.
27
Q. Failure to remove perioxdase may lead to oxidated damage
28 of DNA. Dietary deficiency of selenium has been linked to
the increasing incidence of right-sided colonic cancer."
29 Pausing there, but not to left, so ascending but not
descending?
30 A. That is absolutely right.
