Examination of Witnesses (Questions 20
- 39)
TUESDAY 19 MAY 1998
Mrs Susan Croft, Professor André McLean,
Dr John Marks and Dr Jean Monro
20. It does not need to be the issue, does it,
if it is a food? It is up to the consumer to make that choice,
whether they think it is effective for them or not. To ask it
to jump the medical hurdle or prove claims is to ask it to jump
a hurdle that is effectively too high. As long as there are warnings
about any possibly safety, it can be treated as coffee.
(Professor McLean) Yes, I agree with you. I think
that this is one of the difficulties which COT got into. They
did not really think about what this was being used for and how
to deal with it. It was dealt with as a routine.
Mr Todd
21. As I understand it, you are saying that
we do not stop people from buying salt, sugar and coffee in particular
quantities so there is no particular reason why we should regulate
this in the same way. That would imply that even the 200 mg limit
is something which we should leave to people's own judgment, subject
to some information about the implications.
(Professor McLean) I think that is the truth of the
matter. If you allow people to go and buy 50 mg, there is nothing
to stop them taking 25 tablets.
Mr Todd: That would be fine provided it were
not marketed in any sense as a medical solution. Is there evidence
from within your membership that this is understood to be a medical
solution to some?
Chairman: We are going to move on to that next
with Fiona Jones's questions.
Ms Jones
22. CHC have claimed various benefits in relation
to vitamin B6, especially in relation to premenstrual syndrome.
I understand that Professor McLean said that there are good arguments
to suggest that the evidence for the efficiency of it is minor
or insufficient. I wonder whether you think that you harm your
case by claiming unproven benefits for vitamin B6?
(Dr Marks) I would say that at the moment it is not
proven. I happen to believe that it is effective in some cases
certainly of PMT or PMS, whichever term you like to use. That
is the one where I have advised its use most and I am quite convinced
it had some effect. I have a considerable measure of deja vu in
coming to this Committee because it is almost exactly 40 years
ago that I sat on a similar committee in the other place where
they were considering vitamin E, where they were wanting to say
this was not a vitamin. I was defending it being allowed to still
be used, as I am here now, because I was convinced myself, having
clinical experience, that it had a place. I could not prove it.
We won our case. It continued and it is now known to be a very
valuable antioxidant, probably one of the most valuable of the
antioxidants. The situation is very like that. I cannot prove
it. The work has not been done. There is a lot of recent work
which suggests how it may work in PMT, which is a biochemical
effect within the brain on the GABAA receptors. I think I probably
will not go into it in detail but in at least some people with
PMT there is an aberrant metabolism of the progesterone type of
steroid. It goes through a different pathway. This will affect
adversely cells within the brain that have GABAA receptors on
them. Of course, one of the functions of pyridoxine is to influence
the GABA activity and I believe that that may be—I am not
putting it any higher than that—the mechanism by which it
works. I believe it does work. I cannot prove it to you. I totally
accept that, but we have a tremendous number of people who are
using it, not just for a month and giving it up because it is
no good. As you can see from quite a lot of the written material
produced to you, they are using it for 10 or 20 years. On the
whole, consumers do not use stuff that does not work for that
length of time. Consumers are not crazy, particularly if they
are having to pay for the stuff anyway.
23. So there is no scientific evidence as such
available at this time to suggest—?
(Professor McLean) The level of evidence that is required
for a substance to get a product licence is really very high.
The kind of trials and studies which have been done, I would say,
are close to the evidence which was enough to get a product licence
for, say, efamol in eczema. However, there is nobody coordinating
them; there is no big, financial group which has the necessary
strength to put that together. Overall, the evidence suggests
rather strongly to me that there are some people who get considerable
benefit. The question is how many and can that evidence be put
together. At the moment, it has not been put together but if we
were talking about efficacy, which I understand we are not at
the moment, then I would say I think it is almost certainly efficacious.
Another thing that I think needs to be said is that the degree
of uncertainty in science and nutrition is inevitably rather great.
For instance, 20 years ago, we would say that an ordinary diet
provided enough vitamins for anybody. That is what I used to teach
my students. Now, it is perfectly clear that that is not true.
That is not how we have evolved because evolution does not deal
with people who are more than about 30 years old. For instance,
we certainly need about five times as much folic acid as we thought
we needed 20 years ago. The same is true for vitamin E and many
other things. The confident statements which regulatory committees
make about vitamins have to be taken with a considerable degree
of mistrust because they can only tell us what has been shown
very clearly so far and that often is inadequate.
(Dr Monro) Although we are not considering efficacy
in disease, we are considering efficacy in healthy states which
are not actually a fixed point. They are a continuum into disease.
People have the opportunity of assisting themselves with nutrition,
which is part of a lifestyle, into a more healthy state. I think
that is something which should be considered because there is
a lot of evidence that many things will rob vitamin B6 from our
bodies. For example, smoking. Also, people who have the contraceptive
pill or who are on hormone replacement have an extra requirement
for B6. These are not natural substances necessarily; they are
taken to induce a particular state of wellbeing. There are a lot
of things which will rob vitamin B6 without it being necessarily
something that has to be prescribed as a remedy to put things
right.
(Mrs Croft) About 70 per cent of my database are women
and about 70 per cent of those do take vitamin B6 because they
believe it helps them with PMS. The average amount they take is
100 mg a day. We must not lose sight of the fact that this is
a food. I have to tell you I take vitamin B6. I have taken it
for more than 12 years. I take 125 mg a day or 110 mg a day, certainly
more than 100 mg a day. I do not take it for PMS; I take it because
I was told a very, very long time ago that it would reduce the
severity of my migraine and it does. It does not stop me getting
them but they are not so severe. This is a food supplement. I
do not know how it works; I do not know how it helps me, but I
do know that it does and we should not be denied these natural
substances that do help. We may not know how they work but that
does not mean they do not work.
24. Can we move on to large intakes? Is it plausible,
scientifically, that doses of up to 200 times the Reference Nutrient
Intakes for individuals can be of any benefit to people's health?
(Dr Marks) The answer to that is yes. There is quite
a lot of evidence on that. Apart from anything else, that reference
value intake may be wrong anyway. It is probably right by a factor
of two to four, something of that sort. I totally accept that
there are many things that influence it. I return to the same
matter of vitamin E, where now the dose which is believed to be
appropriate is of the order of 40 to 50 times—all right,
not 200; I accept that—the reputed ordinary daily dose.
Folic acid is now somewhere round about 100 times, if you are
trying to prevent the homocysteine effect on cardiac disease.
It is of that order. At that level of difference, 50 or 100, yes,
there is quite a lot of evidence now in this group of general
substances.
25. Would you view it as a possible compromise
if the actual recommended safety level for B6 was lowered? Would
you view it as an acceptable compromise if the recommended daily
intake was lowered?
(Dr Marks) Do you mean raised?
26. The upper safety level.
(Dr Marks) If the recommended daily intake was—?
27. If we changed the upper safety level, would
you view that as an acceptable compromise?
(Dr Marks) Yes, if it were changed to not more than,
say, 200 mg a day. I would say totally, 100 per cent. There is
a toxic dose. The toxicity has been demonstrated. It is well known.
It is not what was described by Dr Dalton. I think she made a
very good observation, but it was not a pyridoxine toxicity—
Chairman: We had better abandon this now because
we want to come on to the Dalton study in a moment.
Mr Todd
28. I was certainly interested in the scientific
analysis of how people understand this may work or not, but I
would take the point that many people take many different things
they think work for them and we do not interfere. I am more interested
in how it is marketed to your members, how it is actually presented
in the health shops and so on that they go to. Is it marketed
as a food supplement or is it marketed as something which is going
to solve what they perceive as a medical problem?
(Mrs Croft) It is marketed as a food supplement and
makes no claims.
29. It makes no claims for its own efficacy;
it leaves people to make their own judgment as to whether it works
or not?
(Mrs Croft) Yes. There are places where they can seek
advice from practitioners, even in some of the stores where they
have trained staff. Nevertheless, they are sold without any claims
being made.
Mrs Organ
30. I am a little concerned to find that no
work has been done to prove the efficacy of vitamin B6 for women
with PMS.
(Professor McLean) But there has. There have been
several studies.
31. It has not been proven? Is that what you
are saying?
(Dr Marks) It depends upon the level of proof that
you demand. I would demand a very high level of proof if you were
saying that I make a solid claim as a medicine. Then you need
a certain proof, but a lot of work has been done and many thousands
of people studied.
32. But we are not selling this product as a
medicine; we are marketing it as a food supplement so the proven
link between its ability to help women with PMS does not have
to be such a high level.
(Dr Marks) No, because I answered the question, "Can
you prove that it works in PMS?" PMS is a medical condition
and therefore I have to go on to the Medicines Act proof.
33. Obviously, the manufacturers who are marketing
this are large, wealthy pharmaceutical companies.
(Mrs Croft) No, that is not true. The majority of
them are very small companies, not attached to the pharmaceutical
industry at all.
34. In America they are probably.
(Mrs Croft) Maybe.
Mrs Organ: You are saying that, in America,
large companies that are marketing vitamin B6 have not been doing
considerable studies to actually be able to prove a link at the
level that is required for medicines?
Chairman
35. That is precisely your point, is it not,
about the costs involved in doing that kind of work?
(Dr Monro) Yes, but where a medicine's efficacy has
been proved, it is usually a pharmacological agent that is not
part of our normal repertoire of foods that we ingest. The difficulty
about doing a food study is that the complexity of introducing
a single substance and observing effects is much more difficult.
With a drug, you can have an intervention or do a cross over double
blind study. With a food substance, it is already in the food
chain. It is already there as part of a person's normal diet to
some extent. The requirements vary from individual to individual,
depending upon the pollutants they meet, for example. It is far
more difficult to establish cause and effect, although it has
been done. In fact, there is a huge study, not to do with PMS
but to do with coronary heart disease, which came from Harvard,
published in the journal of the American Medical Association,
in 14 years, 80,000 people, showing that the higher the intake
of vitamin B6 as a supplement in the diets of these people the
fewer the coronaries and there is an absolute correlation. That
was published in February of this year.
Mr Mitchell
36. We are going down a dead end street here
because the fact of the matter is that it is a diet supplement.
It does not have to prove any medicinal claims that are made for
it. Those are what the consumer believes them to be. I have been
taking massive doses of vitamin C each day since I had an interview
in the early seventies with Linus Pauley who convinced me that
that was beneficial. It is my right to do that. Unless there are
harmful effects that can be demonstrated or that I need to be
warned about, it is a matter of my choice of what I take.
(Mrs Croft) Quite right.
Mr Hayes
37. I have had a lot of conversations and meetings
about this and generally speaking I have been impressed by the
case that has been made by organisations like yours. However,
this does need to be tested a little more thoroughly. The government
state in their memorandum that there has been little criticism
of the COT review in the mainstream scientific community as evidenced
by a marked lack of correspondence in the pages of the Lancet
and the British Medical Journal. Neither have mainstream consumer
groups or organisations, such as the Nutrition Society, the British
Dietetic Society and the British Medical Association, expressed
concern about the proposed controls, despite having been given
a clear opportunity to do so. There does not seem to have been,
from the mainstream consumer groups, a great deal of protest.
What are your comments on that?
(Mrs Croft) I think that statement is, to a large
extent, untrue. There have been representations. You probably
have seen this document by a group calling themselves the vitamin
B6 Scientific Task Group. That is a group of 200 scientists and
doctors who, four times, have gone back either to COT or to Mr
Rooker to say, "You have got it wrong. This is how you got
it wrong and where you got it wrong and why." Just because
they have not chosen to make this public through mainstream press
does not mean that they have not made their criticisms. This is
a very important piece of evidence to say that this restriction
is wrong. You say that these other groups have not criticised
the government. They have not applauded the government either,
as far as I can see. This is an important document. There are
200 British scientists and doctors who have criticised. Do not
forget, there is also the American document that was published,
I believe, on 7 April from the American Academy of Sciences. They
have come out and said that 200 mg is the safe level but, erring
on the side of caution, they will use a factor of two and are
recommending 100 mg for safety. Why is there this huge discrepancy?
To say there is no criticism is absolutely wrong. Dr John Marks
is one of those 200 doctors.
38. I did not say there had been no criticism.
I named specific groups. I cannot speak for my colleagues but
all of the correspondence that I have had on this in my own constituency,
South Lincolnshire, has been from consumers. I have had no correspondence
from doctors expressing concern about this. It has all come from
the health food lobby, we might argue, and I have been most impressed
by it, as I said at the beginning of my remarks, but I have to
say that it has not come from professionals. In the press, it
has only begun to emerge from professionals, notwithstanding this
report, very recently. Why is that?
(Dr Marks) I am not surprised at all because since
it is a dietary supplement it is not something that doctors, on
the whole, are concerned about. I considered at one stage writing
to the BMJ with an argument and I thought no; that is the wrong
medium. They are just not concerned about it. In Cambridge, the
average medical student gets two and a half hours in the whole
of his course on nutrition. I find it very sad indeed. I have
tried unsuccessfully to increase the amount but it is not regarded
as being important.
39. That is a compelling case. What about the
Nutrition Society?
(Dr Marks) The Nutrition Society is also, I would
have said, much more interested in what happens in mice and rats.
If you look at the Nutrition Society Journal, it is filled largely
with giving X to rats and mice. There are other groups which perhaps
could have come in, but I think there are some of us who prefer
to work with humans.
Chairman: It may interest you to know that the
BMA declined the opportunity to provide this Committee with evidence
on this inquiry, so I think that backs up your argument.
|
