Day 033 - 10 Oct 94 - Page 22
1 colon.
2
3 Studies of Americans have shown the same thing. Cohort
4 studies are different in that one prospectively follows a
5 group of people whose diet is already known in advance.
6 Walter Willett's nurses' study did identify an association
7 with meat consumption; that regular meat consumption
8 was associated with higher rates of colon cancer. The
9 mechanisms, however, have been elaborated since Dr.
10 Burkitt's early work, I guess, 20, 30 years ago.
11
12 We also know that not only as Dr. Burkitt suggested that
13 fibre can delude carcinogens and absorb carcinogens, but,
14 in addition, when meat is heated in the process of cooking
15 carcinogens form on its surface and these are presented,
16 if you will, the beach head in the body where carcinogens
17 enter may be the colon, because it is the digestive tract
18 that absorbs nutrients and water from foods. It is now
19 quite well known that when meat is heated carcinogens form
20 on its surface and these are presented to the digestive
21 tract. By carcinogens I mean cancer causing hydrocarbons
22 that are in meat and arise in the process of cooking.
23
24 One additional mechanism is also important and has been
25 the subject of a number of studies, and that is that a
26 diet that is high in fibre and low in fat (because I think
27 the two probably work together) modifies the digestive
28 flora, the bacteria that normally inhabit the intestinal
29 tract, such that when the diet is high in fat and low in
30 fibre there are more the type of bacteria that will
31 convert bile acids, which are in the digestive tract, to
32 help absorb fat, to convert these to carcinogenic
33 secondary bile acids.
34
35 So, one has not only international between countries
36 correlations, one also has case-control studies, cohort
37 studies, and mechanisms that are well established and that
38 would help explain this association.
39
40 Again, like breast cancer, there have been some studies
41 that have found no relationship, but the preponderance of
42 evidence has been such that cancer authorities in the
43 United States have felt that it is long past the time to
44 make recommendations that Americans increase fibre
45 consumption and reduce fat consumption.
46
47 Q. In order to avoid colon cancer?
48 A. In order to avoid colon cancer, yes.
49
50 Q. Just going back to the carcinogens forming on the surface
51 of meat; when you say it is well known, it is not
52 something that is generally, I believe, well known in this
53 country. Do you want to explain the status of that point
54 of view in America?
55 A. Yes. I believe it is probably well known in this
56 country amongst cancer researchers. Regrettably, many of
57 these reports have been gathering dust in medical
58 libraries or on the desks of cancer researchers and have
59 not, by and large, been made available to individuals who
60 might be interested in modifying their diets or be
