Examination of Witness (Questions 180 - 199)
TUESDAY 19 MAY 1998
PROFESSOR H F WOODS
180. But did nutritional evaluation in terms of its effects
for those who take it enter into its evaluation in any way?
(Professor Woods) I understand now exactly what you
mean. You are asking me whether or not we considered the efficacy.
181. Yes.
(Professor Woods) No. The efficacy of this particular
compound for whatever use was not a part of our assessment and
is not usually a part of our assessment. The efficacy of a compound
such as this used therapeutically is a matter for the Committee
on Safety of Medicines.
182. So that should not have coloured your views in any way.
Have you examined any other naturally occurring essential nutrients
in this kind of way?
(Professor Woods) Yes, I have mentioned to Mr Todd
that we have recently finished an examination of the effects of
certain metals, particularly metals in water, and certain of those
metals are certainly essential nutrients; they are trace elements
that you and I need.
183. So it is fairly rare for you to consider the toxicity
of essential nutrients?
(Professor Woods) Relatively rare, yes.
184. Does it carry the implication if you are saying that
the minimum intake should be 10 mg, since you can get, say, much
more than a 200 mg dose out of a sack of potatoes, that the sack
of potatoes should then carry warnings that it would be a mistake
to eat this sack all at once because it would mean ingesting more
than 10 mg of vitamin B6?
(Professor Woods) No, and I do not accept your extrapolation.
185. But is that not the kind of reductio ad absurdum
that you are going to be open to if you introduce that kind of
minimum level?
(Professor Woods) Well, Mr Mitchell, I have not heard
that argument until this afternoon.
186. But it is a valid one, is it not?
(Professor Woods) It is an argument, but I am not
sure about its validity.
187. You did not do any original research in considering
the toxicity of B6?
(Professor Woods) Myself or my Committee?
188. No, the Committee.
(Professor Woods) I myself have done original research
on vitamin B6 and if you examine the literature between 1972 and
1976, you will see a series of four papers, including one in Nature
in which the group in which I was working looked at certain aspects
of vitamin B6 metabolism, particularly in relation to high dose
oral contraceptives and the effect of those sorts of preparations
on aromatic and amino acid metabolism in man.
189. What did that tell us about the minimum or maximum dosage?
(Professor Woods) It told you nothing about that,
but it answers your question in relation to whether or not I or
others have done research.
190. But since most of the research you examined, and I understand
that you looked at about 100 or so papers of which only two had
any recommendations on maximum dosage levels and on the effects
of high dosages, it does seem a fairly small sample to base your
conclusions on.
(Professor Woods) Well, we did not base our conclusions
on one sample. I think that you raise, sir, a very important point
and I think it is a point that has caused difficulty for the Committee
on Toxicity and that is that at the time when we carried out these
assessments, the rules of procedure under which we were working
did not allow us to publish our full working documents and because
we were not able to publish our full working documents, there
is no doubt that some people have assumed that we only based our
conclusions on a very small number of papers and did not, as we
did do, survey a very large amount of literature.
191. That is assassination by innuendo. How many of the papers
you examined indicated problems with doses of less than 100 mg?
How many?
(Professor Woods) We have indicated what we looked
upon as being the two key studies in this regard and that is the
Dalton and Dalton paper—I do not refer to the Dalton and
Dalton letter, but I refer to the paper in the peer review journal—and
also the dog study that Phillips and colleagues undertook.
192. And Dr Ian Munro, who was one of the people doing the
dog study, said that you have misused his data.
(Professor Woods) Well, he is entitled to that opinion,
sir.
193. Well, have you misused his data?
(Professor Woods) No, we have not misused his data.
194. So he is wrong in saying that his data which he gathered
was misused?
(Professor Woods) He is, in our opinion, wrong to
say that, yes.
195. Okay. Now, you brought that dog study into your second
look at the issue. In your first look at the issue you said that
your Committee agreed that it was not necessary to consider the
animal toxicity data, which is the dog study, "since adequate
human data were available". That is correct, is it not?
(Professor Woods) We looked at the dog study, but,
as I have said, sir—
196. But it was not considered.
(Professor Woods) I wonder if I might be allowed to
finish my statement. We used both animal and human data and what
we found was important in relation to the dog study was that the
dog study gave an indication which supported our interpretation
and usage of the human data.
197. But in the first report you said that it was not necessary
to consider the animal toxicity data "since adequate human
data were available". That is what you said.
(Professor Woods) Yes.
198. So it influenced your view, but you did not consider
it, is what you are saying?
(Professor Woods) No. It influenced our view, but
we did not use it in order to calculate the dosage level that
we arrived at; we used the human study.
199. Which is my point of course. However, in the second
review, that dog study had moved into an essential supporting
role because by that stage the Dalton and Dalton Report was becoming
discredited. Indeed we shall go on to look at the way it has been
discredited this afternoon. In the second report, you say that
animal toxicity data, particularly the 1978 Phillips study, are
seen as integral to support your recommendations, and indeed you
say that the Dalton and Dalton study "would not have been
used by itself to derive a numerical recommended intake, if this
were the only information available". Right?
(Professor Woods) Yes.
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