High Doses of Antioxidants Including Vitamin C Do
Not Decrease the Efficacy of Chemotherapy
The idea that the use of antioxidants decreases the
efficacy of chemotherapy is being used more and more by orthodox oncologists.
It is based upon their hypothesis that anything which decreases the
oxidant effect of drugs will decrease the efficacy of chemotherapy.
More and more I hear this from my patients after they are diagnosed
and chemotherapy is discussed with them by their oncologists. This opinion
is not universal, but my guess is that about 75% of oncologists hold
Their view is that chemotherapy destroys tumor tissue
because it introduces powerful oxidation products, free radicals, and
that anything which decreases that must interfere with treatment. They
know they are using sub-lethal amounts of toxic compounds which would
never pass FDA standards in any different context. The aim is to kill
all the tumor tissue without killing all the other tissues in the body.
This is always a close call. Therefore, since vitamin C is a good antioxidant
it must not be given with chemotherapy. One of my patients was told
by his oncologist that if he took vitamin C he would not be given any
Well, what are the facts? The first fact is that there
are no clinical series which show that patients given vitamin C and
chemotherapy fare worse than those not given this vitamin. On the contrary,
all the published series show just the opposite. I have treated over
1,100 cases with large doses of vitamin C and most of them had chemotherapy.1-4
I have examined the follow up data and find that the mean difference
on prolongation of life was heavily in favor of the use of the
vitamins. In the first series I published with Linus Pauling those patients
on my program lived 10 to 20 times as long as the patients not receiving
Recently Kedar N. Prasad et al.5 after reviewing
71 scientific papers, found no evidence that antioxidants did interfere
with the therapeutic effect of chemotherapy and, on the contrary, suggest
the hypothesis that it would increase the efficacy. He is properly cautious,
but anyone reading his paper knows that it is clear the probability
that these antioxidants prevent the therapeutic activity of chemotherapy
is very low, and the probability that they do the opposite, i.e enhance
the action of these toxic drugs, is relatively high. Prasad et al.6
concluded, "Antioxidants such as retinoids, vitamin E, vitamin C and
carotenoids inhibit the growth of cancer cells. These antioxidants individually,
and in combination, enhance the effects of x-irradiation, chemotherapeutic
agents, and certain biological response modifiers such as hyperthermia,
sodium butyrate and interferon, on cancer cells. Antioxidants individually
protect normal cells against some of the toxicities produced by these
therapeutic agents. Therefore, the fear of oncologists and radiation
therapists that these antioxidants may protect cancer cells against
free radicals that are generated by these agents is unfounded. It should
be pointed out that other antioxidants such as sulfhydryl compounds
will protect cancer cells at least against radiation damage. This is
not true for any of the proposed antioxidant vitamins and carotenoids."
Even earlier Charles B. Simone et al.7 on
the basis of a large number of clinical studies (he also examined 71
scientific papers) came to the same conclusion. He reported, "In a recent
study of 50 patients with early-stage breast cancer I evaluated the
treatment side effects of radiation alone, or radiation combined with
chemotherapy, while the patients took therapeutic doses of nutrients.
Patients also followed the Simone Ten Point Plan. Patients were asked
to evaluate their own response to the treatment in terms of its impact
on their quality of life. The results of the study were impressive:
"More than 90% of both groups noted improvement in their physical symptoms,
cognitive ability, performance, sexual function, general well-being
and life satisfaction. Not one subject in either group reported a worsening
of symptoms." He concluded, "...cancer patients should modify their
lifestyles using the Ten Point Plan, which included modifying nutritional
factors and taking certain vitamins and minerals especially if they
are receiving chemotherapy, and/or radiation." (my emphasis)
Labriola et al.8 concluded that vitamin
C may prevent the therapeutic effect of chemotherapy if given concurrently
and recommended that antioxidants be withheld until after the chemotherapy
is completed. It is not clear whether they meant that the antioxidants
should be withheld throughout the entire series of chemotherapy sessions
or that it should be withheld only for the day that chemotherapy is
being given. If the latter is his suggestion, there is no harm done
to the patients. Most of them cannot take anything, including vitamins,
during these sessions. He based his conclusion on one case which suggested
this had happened and upon a hypothetical examination of the role of
free radicals and antioxidants on the action of chemotherapy on cancer
His report elicited two rebuttals, Reilly9
and Gignac.10 I will not repeat the arguments, but it was
evident that Dr. Labriola was not convinced by the points put forward
by Reilly and Gignac. I think the factoid repeated by Dr. Labriola would
have a much better chance of becoming a fact if he had considered the
(1) What is the therapeutic value of chemotherapy without
any antioxidants? Even within the field of standard oncology there is
a debate whether chemotherapy has any merit except for a small number
of cancers (Moss).11 Before one can claim that a treatment
has been inhibited, surely there must be pretty good evidence that the
treatment has any merit to begin with. It is possible (we do not know
the probability for this) that chemotherapy interferes with the therapeutic
value of the antioxidants. Almost all the studies testing large doses
of vitamin C yielded positive results while there is no such unanimity
with respect to chemotherapy.
(2) The difference between possibility and probability.
Most people do not distinguish between these two. Theoretically anything
is possible, and it is certainly possible that taking vitamin C might
prevent the toxic “beneficial” effect of chemotherapy. In the same way
when one buys a lottery ticket, it is possible they may win. People
confuse these two terms, which is why lotteries are so popular. The
real statistic is the probability. What is the probability that patients
receiving vitamin C during their chemotherapy will not fare as well?
The lottery ticket may give one a probability of winning of one in a
million, and the possibility that vitamin C may prevent the therapeutic
effect of chemotherapy may be equally low. We can only assume from the
literature reviewed by Simone, by Prasad, by Lamson and Brignall, and
more recently by Moss12 that the real probability must be
extremely low. As I have pointed out earlier, I have seen no evidence
that adding vitamin C inhibited the therapeutic effect of chemotherapy.
Just the opposite. Patients on my orthomolecular program live substantially
longer and about 40% achieved over four year cure rates.13
(3) If he had not tried to bolster his argument by referring
so frequently to the peer-reviewed journal in which his paper appeared.
This is certainly no guarantee of fact. The first factoid that vitamin
C caused kidney stones appeared in eminently peer-reviewed journals.
All the factoids regarding vitamins appeared first in peer-reviewed
journals. You may recall Linus Pauling's joke that peers are people
who pee together. I can assure you that articles attacking the use of
vitamins have very ready access to peer-reviewed journals, but they
would not have accepted their report had they tried to conclude from
one patient that vitamin C taken during chemotherapy was therapeutic.
This would not even be sent to the peer review committee because they
do not accept anecdotes - unless of course they become scientific when
they contain something adverse against vitamins.
(4) Moss points out that oncologists have no objection
to using xenobiotic antioxidants during chemotherapy. This includes
Amifostine which decreases the toxicity of radiation but is too toxic
on its own and is not used; Mesna, a drug used around the world to protect
against the toxic side effects of ifosfamide which damages the urinary
system; and Cardiozane, which counters Adriamycin's toxicity. There
are over 500 papers showing the safety of the latter drug. In one clinical
trial using a drug similar to Adriamycin, one-quarter of the patients
suffered damage to their hearts. When given Cardiozane concurrently
only 7% did. Thus it appears that only orthomolecular or natural antioxidants
are potentially dangerous. Synthetic antioxidants protect against the
toxic effect of drugs but do not increase their therapeutic value. In
sharp contrast, natural antioxidants not only protect against the toxic
effect of drugs but also increase their efficacy in destroying
(5) Dr. Labriola emphasizes that long term studies must
be used. I agree, and for this reason I followed up my patients since
1977. In my series, hardly any patients receiving chemotherapy but not
antioxidants survived very long. But chemotherapy is used by many oncologists
who know it will not extend life, because there is nothing else that
they can do and they feel they have to do something.
A. Hoffer MD PhD FRCP(C)
Suite 3 - 2727 Quadra Street
Victoria, British Columbia V8T 4E5 Canada
1. Hoffer A & Pauling L: Hardin Jones biostatistical
analysis of mortality data for cohorts of cancer patients with a large
fraction surviving at the termination of the study and a comparison
of survival times of cancer patients receiving large regular oral doses
of vitamin C and other nutrients with similar patients not receiving
those doses. J Orthomolecular Medicine 5:143-154, 1990. Reprinted
in, Cancer and Vitamin C, E Cameron and L Pauling, Camino Books,
Inc. P.O. Box 59026, Phil. PA, 19102, 1993.
2. Hoffer A & Pauling L: Hardin Jones biostatistical
analysis of mortality data for a second set of cohorts of cancer patients
with a large fraction surviving at the termination of the study and
a comparison of survival times of cancer patients receiving large regular
oral doses of vitamin C and other nutrients with similar patients not
receiving these doses. J of Orthomolecular Medicine, 8:1547-167,
3. Hoffer A: Orthomolecular Oncology. In, Adjuvant
Nutrition in Cancer Treatment, Eds. P Quillin & RM Williams.
1992 Symposium Proceedings, Sponsored by Cancer Treatment Research Foundation
and American College of Nutrition. Cancer Treatment Research Foundation,
3455 Salt Creek Lane, Suite 200, Arlington Heights, IL 60005-1090, 331-362,
4. Hoffer A. One Patient's Recovery From Lymphoma. Townsend
Letter for Doctors and Patients #160:50-51, 1996.
5. Prasad KN, Kumar A, Kochupillai V & Cole WC.
High Doses of Multiple Antioxidant Vitamins: Essential Ingredients in
Improving the Efficacy of Standard Cancer Therapy. Journal American
College of Nutrition 18:13-25, 1999.
6. Prasad KN, Cole WC & Prasad JE. Multiple Antioxidant
Vitamins as an Adjunct to Standard and Experimental Cancer Therapies.
Z.Onkol/J. of Oncol 31:1201-1078, 1999.
7. Simone CB, Simone NL & Simone CB. Nutrients and
Cancer Treatment. International Journal of Integrative Medicine
8. Labriola D & Livingston R. Possible Interactions
Between Dietary Antioxidants and Chemotherapy. Oncology 13:1003-1008,
1999, and Editorial to Townsend Letter for Doctors and Patients,
9. Reilly P. Dr. Labriola's Editorial on Antioxidants
and Chemotherapy, Townsend Letter for Doctors and Patients Feb/Mar
10. Gignac MA. Antioxidants and Chemotherapy. What You
Need to Know Before Following Dr. Labriola's Advice. Townsend Letter
for Doctors and Patients Feb/March 2000, 88-89.
11. Moss RW. Questioning Chemotherapy. Equinox
Press, Brooklyn, New York.
12. Moss RW. Antioxidants Against Cancer. Equinox
Presss Inc. Brooklyn, New York, 1999.
13. Hoffer A. Vitamin C and Cancer. Quarry Press,
Kingston, ON 2000.