Letter to the Chairman from Dr John Marks
(E1 (mc))
I write, as one of those who is quoted in various
reports that are circulating on the matter of the safety of pyridoxine,
to say how appalled I am at the report made by the COT and to
welcome the fact that you are undertaking an enquiry on the matter.
I have been working in the field of nutrition,
particularly the human use of vitamins, since the 1950s and have
written no less than three textbooks on this subject, a monograph
on vitamin safety which has been translated into various other
languages, chapters in other textbooks and various research papers.
I am currently involved in a new edition of one of these textbooks
and writing another.
My interest in the specific matter of Dr Dalton's
un-orthodox views on the dosage at which neuropathy can occur
dates back to the time of her original letter to the Lancet.
At that stage I was writing one of my textbooks and the monograph
on vitamin safety. I sought access to the original clinical reports,
since her conclusions did not agree with those of any of the experts.
I could not get access to that information.
Since then I have kept myself informed of the
substantial body of evidence which demonstrates that Dr Dalton's
conclusions were totally inaccurate. I will not rehearse further
the mass of evidence which leads to this conclusion. I will merely
summarise my reasons for my view that the COT report is fundamentally
flawed:
— Neuropathy at high pyridoxine dosage
was well known to those of us who were working in the field, but
Dr Dalton's clinical description of what she found did not accord
with this, nor did (or does) her reported incidence of side effects
accord with that reported by others. Her original study was substantially
flawed, even by the lower standards which operated at that time.
— Medical history abounds with adverse
effects first recognised by general practitioners, but I know
of no other accepted side effect which has not been confirmed
by specialists. The extent of the literature on the subject testifies
to the efforts which have been made to attempt to validate her
views all without success.
— I support the fundamental scientific
dictum that a single report, unsubstantiated by others should
not be accepted.
— The safety factor ratio devised by
COT to demonstate that animal studies support the views of Dr
Dalton is untenable for nutritional substances and is substantially
outside those normally used for substances of known toxicity.
As a result, I support the views that:
1. COT should indicate which other clinical
studies support Dr Dalton's view.
2. COT should justify their safety factor
by reference to other nutrients.
3. Above all, in view of the dispute, an
independent study should be undertaken to modern standards to
confirm or refute COT conclusions before pyridoxine is subjected
to the new regulations.
If my experience or knowledge are of any value
to your Committee I shall be pleased to make them available to
avoid this travesty.
11 April 1998
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