Day 269 - 25 Jun 96 - Page 10


     
     1        what Dr. Arnott said that epidemiological evidence requires
     2        support from independent sources the best of which is
     3        experiment which provide a rational mechanism?
     4        A.   Yes, I think so.  I mean, there was a stage when there
     5        was a very strong correlation between the sale of nylon
     6        stockings and the rise in coronary heart disease in Denmark
     7        after the last war, but you really require to have a
     8        logical biological mechanism to explain the connection and
     9        nobody came up with a biological mechanism to explain the
    10        connection with the sale of nylon stockings.  And, in fact,
    11        the epidemiological evidence proved that it was wrong
    12        because on follow-up it did not pan out.  The sale of nylon
    13        stockings leveled off and coronary heart disease still
    14        continued to rise.
    15
    16        But I think most people in science would say we need a bit
    17        more than an association between high risk; we need an
    18        explanation for that, and the explanations come from the
    19        experimental laboratory.  I think what I am saying is that
    20        there is a very heavy weight of evidence showing that in
    21        virtually all experimental animal models saturated fats, a
    22        high saturated fat diet will induce changes in the blood
    23        vessels which, although not identical because there are
    24        species differences, are enough to make people believe that
    25        these are an explanation for what is happening in the
    26        human.
    27
    28        There were studies, I believe it was Whistler, some time
    29        ago done in primates where he used the actual canteen diets
    30        that were rich in this kind of saturated fat diets that we
    31        are talking about and compared them with prudent diets
    32        which were being recommended by the American Heart
    33        Association, and there was a very clear difference in the
    34        genesis of atherosclerosis which was almost identical.  You
    35        could not really tell the difference in the primate with
    36        the human atheroma in the primates fed the canteen diet as
    37        opposed to those fed the prudent diet.
    38
    39        So I think you need that kind of supporting evidence, my
    40        Lord, to translate what you see as a difference between two
    41        populations and what you suspect from measuring the risk
    42        factors in those populations to translate it into a
    43        mechanism at the biological level.
    44
    45   MS. STEEL:  Right.  So you are looking for some kind of
    46        plausible biological mechanism?
    47        A.   Yes, and I think we have that.  You essentially have
    48        to test your hypothesis in some way and it is exceedingly
    49        difficult to test a hypothesis in a human population, for
    50        obvious reasons, so you have resort to the experimental
    51        laboratory.
    52
    53   Q.   Right, okay.
    54
    55        "In the lower socio-economic groups one in three men will
    56        have a heart attack or stroke before they reach the age of
    57        retirement.  To get an idea of the contribution to risk one
    58        can use the factorial calculation of the proportions which
    59        gives at 70% of risk a figure of 63,500 heart attacks and
    60        31,750 at a minimum.  If saturated fats and trans-isomers

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