martes, 16 de octubre de 2007

Vitamin C and Cancer

Vía: Cancer Monthly

Vitamin C whether intravenous or oral is one of the most prevalent types of alternative and complimentary cancer therapies. Yet, this nutrient is still considered “controversial” by mainstream oncology. Since two time Nobel Prize winner (in chemistry and peace) Dr. Linus Pauling advocated its use in cancer starting in the late 1970’s, evidence to its efficacy has been quietly and steadily mounting.

Humans Do Not Make Vitamin C

Almost all animals and plants synthesize their own vitamin C except humans and a small number of other animals, including, apes, guinea pigs, the red-vented bulbul, a fruit-eating bat and a species of trout.

Vitamin C and Cancer - Early Work

Pure L-ascorbic acid (vitamin C) was first prepared in 1928 by the Nobel prize winning biochemist Albert Szent-Gyorgyi and in 1932 it was shown that this substance was vitamin C. In 1954 and 1959 Dr. W. J. McCormick, a Canadian physician, hypothesized that cancer is a collagen disease, secondary to a vitamin C deficiency. His theory was based on the fact that collagen is the “mortar” that binds cells together and if cells stick together, tumors would have a more difficult time breaking away and metastasizing. This concept was expanded upon when, in 1966, Dr. Ewan Cameron wrote a book entitled “Hyaluronidase and Cancer.” In it he pointed out that the ground substance or “intercellular cement” that binds cells of normal tissues contains various molecules that strengthen it including glycosaminoglycans and fibrils of collagen. Dr. Cameron discussed how tumors can produce enzymes that breakdown these molecules (i.e. hyaluronidase and collagenase).

Linus Pauling, Ph.D. (chemistry) had been interested in vitamin C for many years and had written previously how people required large amounts of vitamin C (1). Working with Dr. Cameron, Dr. Pauling pointed out that Vitamin C could: A) stimulate normal cells to produce increased amounts of a hyaluronidase inhibitor and; B) increase the number of collagen fibrils made (2). Based on these theories, Drs. Pauling and Cameron embarked on a number of studies to test the efficacy of vitamin C in cancer patients.

Pauling and Cameron Studies Find Improvement in Survival and Quality of Life

In 1976, Drs. Pauling and Cameron reported the survival times of 100 terminal cancer patients who were given supplemental ascorbate (10 grams/daily intravenously) and those of a control group of 1,000 patients of similar status treated by the same clinicians in the same hospital (Vale of Leven Hospital in Scotland) who had been managed identically except for the ascorbate. The 1,000 controls were matched by sex, age, primary tumor type, and clinical status. By August 10, 1976 all 1,000 of the controls had died while 18 of the 100 ascorbate-treated patients were still living. As of September 15, 1979, five ascorbate treated patients were still alive and “living normal lives.” The 100 acorbate-treated patients lived, on the average, 300 days longer than their matched controls with better quality of life (measured from the time all patients were considered “untreatable”).

A second study was performed in 1978 with 100 new ascorbate-treated patients and 1,000 matched controls (about half of the controls were in the original set) (3). This analysis broke out the improved survival times by cancer type. For each type of cancer there was an improvement in survival.

Mayo Clinic Studies Do Not Show Significant Benefit

Pauling’s and Cameron’s studies were not considered the gold standard in clinical studies. The gold standard was and remains the randomized, prospective, double-blind study in which half the patients are randomized to one arm of a study, half to another arm and neither the patient nor the doctor knows who is getting what.

To test whether ascorbate was effective, Dr. Charles Moertel and his colleagues at the Mayo Clinic conducted two randomized placebo controlled studies of patients each with advanced cancer (published in 1979 and 1985) (4). Patients randomized to the treatment group were given 10 grams of oral ascorbate, and neither study showed significant benefit. (In the first Mayo study, median survival was improved two weeks with the ascorbate group.) Because Moertel’s studies were taken as definitive, ascorbate treatment was considered useless. There were however, at least three significant differences between the Mayo Clinic’s “definitive” studies and those of Drs. Pauling and Cameron.

Why the Mayo Clinic Studies Did Not Replicate the Studies by Pauling and Cameron: Difference #1 - In First Mayo Study Most Patients Were Pretreated With Chemo

The overwhelming majority - 87% (52 of 60 patients) of the patients in the first Mayo study had received chemotherapy before the study began. In contrast, only 4% of the patients in Pauling and Cameron study had received chemo. Pauling wrote, “It is known that cytotoxic chemotherapy damages the immune system and might prevent the vitamin C from being effective, inasmuch as it functions mainly by potentiating this system.(5)”

This is a valid critique. A Pubmed search for vitamin C reveals a large number of peer reviewed medical and scientific journal articles that demonstrate that vitamin C scavenges free radicals when it acts as an antioxidant (6), helps neutralize carcinogenic chemicals such as nitrosamine and nitrites (7), enhances lymphocyte function and mobilization of phagocytes (8), improves natural killer cell activities (9), modulates cell growth and differentiation (10), and enhances IgA, IgG and IgM antibody levels (11). Several of these mechanisms are directly related to the body’s immune system and to cancer resistance. Cytotoxic (cell-killing) chemotherapy is notorious for seriously compromising the patient’s immune system by killing the cells that mediate immunity. (Note: in the 1985 Mayo clinic study, this difference was removed as none of the Mayo patients were administered prior chemotherapy.)

Difference #2 - Pauling and Cameron Administered Intravenous Vitamin C, the Mayo Studies Used Only Oral Vitamin C

A commentary published by doctors from the National Institute of Health (NIH) in 2000 pointed out that there was a second significant difference in study design that may have accounted for the different results in the Mayo Clinic studies (12). The authors explained that intravenous (IV) administration (used by Pauling and Cameron) was superior to oral administration (used by Moertel) in respect to bioavailability of the vitamin. The NIH authors said, “It is now clear that intravenous administration of ascorbate can yield very high plasma levels, while oral treatment does not.” The NIH authors concluded that, “Moertel’s results were not comparable to those of Cameron, as ascorbate was given orally and not intravenously. In retrospect, the route of administration may have been key.”(13)

This observation was repeated in another peer reviewed paper published in 2004 in the Annals of Internal Medicine which stated “Because efficacy of vitamin C treatment cannot be judged from clinical trials that use only oral dosing, the role of vitamin C in cancer treatment should be reevaluated.” (14)

Difference #3 - In Pauling’s and Cameron’s Studies, Vitamin C Therapy Continued For the Life of the Patient

And yet a third difference with the Mayo Clinic study was that vitamin C administration was discontinued immediately after a patient could no longer take oral medications or there was progression of the disease. Apparently, in the Pauling and Cameron studies the IV doses continued regardless of the patient’s changing status. Vitamin C was provided during the life of the patient. However, in Moertel’s studies, because it was administered orally, vitamin C was discontinued in a large number of patients whenever there was a sign of worsening. According to writer Ralph Moss, “Because of the odd departure from Cameron’s protocol, patients in the treatment arm of the experiment (in Moertel’s second study) received vitamin C for a median time of only 10 weeks. None of the Mayo patients died while receiving it. Their deaths occurred after the vitamin had been taken away from them.”(15)

Were the Goal of the Mayo Studies to Try to Replicate Pauling and Cameron’s Work or Just Denounce It?

Obviously if the Mayo Clinic studies were designed to test the outcomes of Drs. Pauling and Cameron studies then they should have replicated their methodology of administration (as long as it was scientifically reliable and clinically appropriate). Why didn’t Moertel’s group administer the vitamin intravenously throughout the life of the patient? We don’t know. Any one of these discrepancies described above should have been sufficient for a complete reevaluation, but as is so often the case, the cancer establishment had successfully “proved” that a mere vitamin was of no value in cancer and the case was closed. Or was it?

Vitamin C Therapy is Still Used Today

In the intervening 20 years since Moertel’s last study two trends have continued: 1) patients are being administered IV vitamin C in various cancer clinics around the world and many are showing benefit; 2) the overall plausibility of ascorbic acid administered intravenously as a cancer therapy is being better understood by recent insights into clinical pharmacokinetics and its in vitro cancer-specific cytotoxicity.

Clinical Examples from the National Cancer Institute

A reading of Drs. Cameron and Pauling’s book “Cancer and Vitamin C” provides 26 case histories of patients with various cancers who received a benefit from vitamin C including: brain, breast, prostate, bladder, lung, stomach, ovarian cancer, leukemia and mesothelioma. But, since Cameron and Pauling have been considered advocates of vitamin C, here is another more disinterested source. Three case examples come from a peer reviewed article whose authors come from the National Cancer Institute, the National Institutes of Health, and universities. In a March 2006 article entitled “Intravenously administered vitamin C as cancer therapy: three cases” the authors examined clinical details of three cases in accordance with National Cancer Institute (NCI) Best Case Series guidelines (16). Tumor pathology was verified by pathologists at the NCI who were unaware of diagnosis or treatment. In all three cases (metastatic renal cancer, bladder cancer, and lymphoma), vitamin C demonstrated efficacy.

Although these case histories by themselves are insufficient to prove that vitamin C is an effective treatment for cancer, in the words of these authors, these histories “increase the clinical plausibility of the notion that vitamin C administered intravenously might have effects on cancer under certain circumstances.(17)”

Biological Mechanisms of Vitmain C Are Better Understood Today

The number of peer reviewed journal articles continues to grow that describe the clinical pharmacokinetics and in vitro cancer-specific cytotoxicity of vitamin C. In other words, how Vitamin C is absorbed by the body and can kill cancer cells. For example, an article published in the Annals of Internal Medicine set out the pharmacokinetics of intravenous vitamin C (18); another article in the journal Nature discussed how vitamin C preferentially killed melanoma cells (19); and there have been several articles in Anticancer Research(20), and Oncology (21) that described how ascorbate killed various other cancer cell lines in vitro.

Vitamin C and Collagen

You may recall that Drs. Cameron and Pauling pointed out that Vitamin C could increase the number of collagen fibrils made. In the last 20 years biochemists have described the molecular basis of scurvy and in doing so have helped us understand how vitamin C and collagen are related. Apparently vitamin C plays a role in collagen metabolism by acting as a cofactor in the enzymatic reactions involved in the hydroxylation of praline and lysine. Without this hydroxylation, proper aligned stable helices of the alpha chains are not formed, so the procollagen that is formed is unstable and degraded (22).

Vitamin C May Prolong Life

Vitamin C has many roles that may be associated with fighting cancer including: acting as an anti-oxidant and scavenging free radicals, supporting the various immune cells, modulating cell growth and differentiation, helping to synthesize carnitine which is essential for the transport of fat to mitochondria, and possibly even strengthening collagen. The mounting evidence does suggest that Drs. Pauling and Cameron were right and that vitamin C is a benefit to cancer patients. We will conclude, therefore, with their words, “Vitamin C is not a miraculous cure for cancer, but…it significantly prolongs the life of the cancer patient…We believe that supplemental ascorbate can be of real help to all cancer patients and of quite dramatic benefit to a fortunate few.”(23)

Perhaps our health authorities will recognize the benefit of this “mere” vitamin. But, maybe the issue all along was not the fact that vitamin C is an effective and non-toxic therapy, but rather that drug companies cannot make millions of dollars from it because as a vitamin it is difficult to patent. If this is the case, it would be another example of how economics not medicine decides what therapies are made available for cancer.

Learn more about the economics, politics, and science of cancer by subscribing to CancerWire. It’s free!

End Notes

1 See for example: Pauling L., “Evolution and the need for ascorbic acid” Proc Natl Acad Sci 1970 Dec;67(4):1643-8. Available at: And see Pauling L., “The significance of the evidence about ascorbic acid and the common cold” Proc Natl Acad Sci 1971 Nov;68(11):2678-81 Available at:

2 Ewan Cameron and Linus Pauling, “Cancer and Vitamin C” 1979; see also original research – Cameron E, Pauling L. “Supplemental ascorbate in the supportive treatment of cancer: Prolongation of survival times in terminal human cancer” Proc Natl Acad Sci 1976 Oct;73(10):3685-9. Available at:

3 Ewan Cameron and Linus Pauling, “Cancer and Vitamin C” 1979; see also original research – Cameron E, Pauling L. “Supplemental ascorbate in the supportive treatment of cancer: reevaluation of prolongation of survival times in terminal human cancer.” Proc Natl Acad Sci 1978 Sep;75(9):4538-42. Available at:

4 Moertel CG, et al., “Failure of high-dose vitamin C (ascorbic acid) therapy to benefit patients with advanced cancer. A controlled trial” N Engl J Med. 1979 Sep 27;301(13):687-90. Moertel CG, et al., “High-dose vitamin C versus placebo in the treatment of patients with advanced cancer who have had no prior chemotherapy. A randomized double-blind comparison” N Engl J Med. 1985 Jan 17;312(3):137-41.

5 Ewan Cameron and Linus Pauling, “Cancer and Vitamin C” 1979, pp. 142-3.

6 See for example: Duarte TL, Lunec J. “When is an antioxidant not an antioxidant? A review of novel actions and reactions of vitamin C.” Free Radic Res. 2005 Jul;39(7):671-86.

7 See for example: Tannenbaum SR, et al., “Inhibition of nitrosamine formation by ascorbic acid.” Am J Clin Nutr. 1991 Jan;53(1 Suppl):247S-250S.

8 See for example: Hernanz A, et al., “Effect of age, culture medium and lymphocyte presence on ascorbate content of peritoneal macrophages from mice and guinea pigs during phagocytosis” Int Arch Allergy Appl Immunol. 1990;91(2):166-70.

9 See for example: Heuser G and Vojdani A.. “Enhancement of natural killer cell activity and T and B cell function by buffered vitamin C in patients exposed to toxic chemicals: the role of protein kinase-C” Immunopharmacol Immunotoxicol. 1997 Aug;19(3):291-312.

10 See for example: Mitsumoto Y, et al., A long-lasting vitamin C derivative, ascorbic acid 2-phosphate, increases myogenin gene expression and promotes differentiation in L6 muscle cells.Biochem Biophys Res Commun. 1994 Feb 28;199(1):394-402.

11 See for example: Mitsuzumi H, et al., “Requirement of cytokines for augmentation of the antigen-specific antibody responses by ascorbate in cultured murine T-cell-depleted splenocytes.” Jpn J Pharmacol. 1998 Oct;78(2):169-79.

12 Padayatty SJ, and Levine M. “Reevaluation of ascorbate in cancer treatment: emerging evidence, open minds and serendipity.” J Am Coll Nutr. 2000 Aug;19(4):423-5. Available here:

13 Padayatty SJ, and Levine M. “Reevaluation of ascorbate in cancer treatment: emerging evidence, open minds and serendipity.” J Am Coll Nutr. 2000 Aug;19(4):423-5. See p. 423. Available here:

14 Padayatty SJ,et al., Vitamin C pharmacokinetics: implications for oral and intravenous use. Ann Intern Med. 2004 Apr 6;140(7):533-7. Available here:

15 Ralph W. Moss, The Cancer Industry 1989 p. 224.

16 Padayatty SJ, et al., “Intravenously administered vitamin C as cancer therapy: three cases.” CMAJ. 2006 Mar 28;174(7):937-42. Available here:

17 Padayatty SJ, et al., “Intravenously administered vitamin C as cancer therapy: three cases.” CMAJ. 2006 Mar 28;174(7):937-42. See p. 940.

18 Padayatty SJ,et al., Vitamin C pharmacokinetics: implications for oral and intravenous use. Ann Intern Med. 2004 Apr 6;140(7):533-7. Available here:

19 Bram S, et al., “Vitamin C preferential toxicity for malignant melanoma cells” Nature 1980;284:629-31.

20 Leung PY, et al., “Cytotoxic effect of ascorbate and its derivatives on cultured malignant and nonmalignant cell lines” Anticancer Res1993;13:475-80.

21 Benade L, et al., Synergistic killing of Ehrlich ascites carcinoma cells by ascorbate and 3-amino-1,2,4,-triazole. Oncology 1969;23:33-43.

22 See for example: Davidson, V and Sittman D, The National Medical Series for Independent Study – Biochemistry 3rd Edition 1994, p. 316.

23 Ewan Cameron and Linus Pauling, “Cancer and Vitamin C” 1979 p. 130.

Learn more about the economics, politics, and science of cancer by subscribing to CancerWire. It’s free!

1 comentario:

stavenmorris dijo...

It is regarded that cytotoxic radiation problems the protected technique and might reduce the vitamin C from staying powerful, inasmuch as it capabilities mostly by potentiating this process.

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