Day 031 - 05 Oct 94 - Page 15

     
     1        for its growth.  But once you get up to three per cent of
     2        the energy, or thereabouts, you satisfy the requirements
     3        for tumour growth, and above that you get very little
     4        effect by adding more linoleic acid to the diet.
     5
     6   MS. STEEL:   I think you have said anyway (but just to clarify)
     7        that linoleic acid is essential for all cell -- well, for
     8        cell growth, not just for tumours; is that right?
     9        A.  Yes, it is essential for Mammalia reproduction and for
    10        growth.
    11
    12   Q.   So we could not live on a diet completely devoid of
    13        linoleic acid?
    14        A.  No, you could not reproduce on a diet devoid of
    15        linoleic acid.
    16
    17   MR. JUSTICE BELL:  While you have mentioned promotion, if I go
    18        back to the earlier page, the first page, lines 40 to 51,
    19        "There is firm experimental evidence that dietary fats
    20        act as promoters, the evidence for which will have been
         presented to the court already."  What is the evidence you
    22        are referring to?
    23        A.  Well, it is experimental evidence and I was given a
    24        transcript of some of the earlier discussions in the
    25        court, and it seemed to me that there was discussion about
    26        the experimental evidence at an earlier stage when
    27        Dr. Arnott gave his evidence.  I think there was general
    28        agreement that the experimental evidence in summary is
    29        that fat, a high fat diet, will promote tumour
    30        development;  that is, given there is enough linoleic acid
    31        to provide for the requirements for the growth of the
    32        tumour.
    33
    34   MS. STEEL:   Does the evidence that you have just mentioned
    35        about the linoleic acid promoting tumours help in any way
    36        to explain the differences in incidence of cancer
    37        throughout the world?
    38        A.  Yes, I think it does because it is consistent.  If one
    39        turns again to enclosure 1 I gave you, it is consistent
    40        with the epidemiology which shows that vegetable fat does
         not relate to cancer incidence in the breast.  You can
    42        plot much the same kind of graphs as Caroll has done here
    43        for breast cancer.  You can plot much the same kind of
    44        graphs for colon cancer.  It also means that as
    45        practically all diets throughout the world will contain
    46        about three per cent as a minimum of linoleic acid, the
    47        difference in linoleic acid itself is not going to explain
    48        this wide degree of variability.
    49
    50        The difference in linoleic acid intake from country to 
    51        country will not explain the wide degree of variability, 
    52        so you have to look for some alternative explanation for 
    53        that.  It is in a sense a process of elimination; that if
    54        the vegetable fats are not inducing the cancer, and if the
    55        sea animal fats would be protective against the cancers,
    56        you are left with, again by process of elimination, the
    57        land animal fats.
    58
    59   MR. JUSTICE BELL:  What I suggest you do, Ms. Steel, is look
    60        and see if there is anything else you want to raise.