Day 034 - 11 Oct 94 - Page 12


     
     1        impression it makes on me and the impression it has made
     2        on the Surgeon General.
     3
     4   MR. MORRIS:  Yes.
     5
     6   MR. JUSTICE BELL:  That is not to deter you from asking any
     7        other questions.
     8
     9   MR. MORRIS:  Would you like to go through the cohort studies?
    10        A.  Yes.  Briefly to describe, cohort studies simply mean
    11        that a population is identified, their diets are assessed,
    12        they are then followed prospectively and the incidence of
    13        cancer, the prevalence of cancer rather, is assessed at a
    14        later point.  Four such studies have been done.  Three of
    15        them did not detect an association; one, however, did and
    16        that was the relationship with meat -- meat intake and
    17        breast cancer.
    18
    19        Now, it has been already described and is, I presume, well
    20        understood that cohort studies, where the individuals do
    21        not vary a great deal in fat intake, are not likely to
    22        show an association.  Indeed, that has been a common
    23        criticism of Willett's study, also of Jones's study, that
    24        in each case there was simply very little difference
    25        between the subjects and it was impossible to find a
    26        statistical relationship.  I believe we discussed that
    27        some yesterday.
    28
    29   Q.   It may be helpful to comment a bit on the animal studies
    30        very briefly -- you did mention them -- then ask for your
    31        overall -----
    32
    33   MR. JUSTICE BELL:  What would help me, I think, is -- I do not
    34        know, I have not formed a view yet on whether table 4-7 is
    35        a useful bird's eye view.  But, insofar as it does provide
    36        a bird's eye view of a large number of papers, what does
    37        it demonstrate or mean, if anything, to Dr. Barnard?
    38
    39   MR. MORRIS:  Just on the subject of is it a useful bird's eye
    40        view, is this a kind of objective view that the Surgeon
    41        General is looking at the best studies?
    42        A.  As of 1988, I would say yes.
    43
    44   Q.   OK.  So, in your opinion, is this the best table that
    45        could be put down on one piece of paper at that time?
    46        A.  I think it is a reasonable summary of the research to
    47        date at that time.  It does not -- it is limited -- this
    48        only looks at epidemiologic studies.  It has to be
    49        understood this does not look at any of the evidence on
    50        mechanisms, for example, studies in which high fat diets 
    51        caused obesity and in which obesity was linked to cancer, 
    52        or in which high fat/low fibre diets altered the age of 
    53        menarche and in which lower age of menarche increased the
    54        risk of cancer; such studies would not be included here.
    55        Studies showing links between higher oestrogen levels in
    56        the blood and a higher risk of cancer and dietary links.
    57        Those would not be included here.  Animal studies are not
    58        included here -- this is no more than the epidemiologic
    59        data.
    60

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