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

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