Importance of Vitamin C in fighting cancer

Vitamin C, a natural substance found in many foods and dietary supplements, has long been known to carry several important health benefits. Most notable among these benefits is its critical role in the formation and health maintenance of collagen. [1] Therefore, Vitamin C is important for the health of skin and connective tissues throughout the body.

Intravenous Vitamin C has, in fact, been used for aesthetic purposes such as skin rejuvenation and skin whitening. [2] Vitamin C also is important for the health of bone, cartilage, and teeth, and also plays a very important role in iron absorption; thus impacting overall body health in the many critical ways iron does.

Probably the most controversial, yet exceedingly exciting, a benefit of Vitamin C is its suggested role in fighting cancer. The basis of attributing to Vitamin C this cancer-fighting ability is predicated on two main observations: Vitamin C’s property as an antioxidant and its property as a factor that helps enhance the function of the immune system. Several studies have documented the fact that Vitamin C acts as a natural antioxidant.

This property has been shown in laboratory studies to result in Vitamin C being an effective anti-cancer agent when high concentrations are reached in cells. [3,4] This Vitamin C-induced anti-cancer activity is mediated through the production of hydrogen peroxide (H2O2). H2O2 is an oxygen radical that induces apoptosis (programmed cell death) in cancer cells thus resulting in their elimination. [5,6] It is thought that this effect results from the H2O2 damaging the cells’ DNA; cells that do not immediately undergo apoptosis are damaged and rendered more vulnerable to the anti-cancer effects of chemotherapy and radiation.

The significant role that Vitamin C plays in the proper functioning of the immune system is now well documented. [7] Not only is Vitamin C present in high concentrations in immune cells, such as T cells, it has also been shown to be necessary for these cells’ proper functioning. [8] Vitamin C is also known to be consumed in the body at much higher rates in the presence of infection. The immune system, while commonly and automatically associated with guarding against and fighting infections plays critical roles in health maintenance that span far beyond those confines.

Immune system functioning works not only to prevent and fight infections, help the body’s tissues heal after injury, but also works to combat cancer. The immune system’s role in fighting cancer is a versatile and multifaceted one, involved in not only fighting cancer but also preventing it from taking hold in the first place. [9] The important role that Vitamin C plays in supporting immune function, therefore, highlights the important function of Vitamin C as an anti-cancer agent.

Oral vs. Intravenous Vitamin C

Since Vitamin C cannot be synthesized by the body, it needs to be taken in from outside sources. This is an interesting peculiarity of human physiology since Vitamin C can be synthesized by most animals and plants from the more basic compounds of D-Glucose and D-Galactose. [1] Typically, Vitamin C is taken in orally through ingestion of various foods and dietary supplements. Intravenous administration is another method to take in this compound and has been used and studied as a way to reach a higher concentration of  Vitamin C in the bloodstream, in order to achieve better therapeutic effects. [10]

This turns out to be a consideration of practical significance as studies have shown that oral Vitamin C does not improve survival in cancer [11,12]. Intravenous administration is required in order to achieve the high enough blood concentrations required for the anti-cancer effect of Vitamin C, [13] This is, in large part, due to the variability in the reliability of oral absorption of Vitamin C which results in lower blood concentrations, in general, compared to intravenous administration. [14,15]

The Half-life of Vitamin C in the body is also relatively short (about 2 hours), hence making it difficult for a high enough concentration to be reached at any point in time when the dependence is on gradual absorption through the oral route. As a result of all of these observations, it is now accepted that any significant benefit from Vitamin C in fighting cancer would have to be delivered in the form of high dose intravenous administration of the compound.

Evidence for treatment of cancer

Laboratory studies have shown that Vitamin C is directly toxic to cancer cells as long as certain concentration levels are achieved. [16,17] Animal studies have demonstrated the anti-cancer effects of Vitamin C for cancers of the pancreas, liver, colon, prostate, ovary in addition to mesotheliomas and neuroblastomas.

Until recently, human trials have shown little consistency in confirming the conclusion reached, based on laboratory and animal data, that Vitamin C can help in treating cancer. Early data from a University of Iowa trial on Glioblastoma Multiforme (an aggressive form of brain cancer that is the most common among adults) has recently become available. The results showed that when conventional treatment with chemotherapy and radiation was combined with high dose intravenous Vitamin C, the survival time was increased by 4-6 months compared to conventional treatment without Vitamin C.

In addition to its own anti-cancer properties, Vitamin C has also been shown to increase the effectiveness of certain chemotherapy agents in fighting cancer. Examples include Cisplatin, Dacarbazine, Doxorubicin, and Paclitaxel, in addition to the anti-estrogen agent used in treating breast cancer, Tamoxifen. [18-21] Another beneficial effect of Vitamin C is its ability to reduce the toxicity and side effects associated with chemotherapy. Intravenous high dose Vitamin C has, in fact, been shown to improve quality of life and lessen the side effects of chemotherapy and radiation in breast cancer patients. [21]


In conclusion, high dose Vitamin C therapy remains controversial and not uniformly accepted as a reliable cancer treatment within the mainstream medical dogma.

Despite this, however, a positive view of this therapy combined with increasing evidence for its effectiveness is gathering momentum. There is the agreement that high dose Vitamin C therapy is overall a very safe treatment in cancer patients.

While concerns over interaction with chemotherapy are frequently expressed, studies have in fact shown that it is not only safe with most chemotherapeutic agents but that it also may improve the effectiveness and reduce the side effects of chemotherapy.


  1. K.A. Naidu Vitamin C in human health and disease is still a mystery? an overview: 308 Nutr J, p. 7
  2. Malathi M, Thappa DM. Systemic skin whitening/lightening agents: what is the evidence? Indian J Dermatol Venereol Leprol. 2013;79:842-846
  3. Bram S, Froussard P, Guichard M, Jasmin C, Augery Y, Sinoussi-Barre F, Wray W: Vitamin C preferential toxicity for malignant melanoma cells. Nature 284: 629-631, 1980
  4. Leung PY, Miyashita K, Young M, Tsao CS: Cytotoxic effect of ascorbate and its derivatives on cultured malignant and nonmalignant cell lines. Anticancer Res 13: 475-480, 1993
  5. Claire M. Doskey, Visarut Buranasudja, Brett A. Wagner, Justin G. Wilkes, Juan Du, Joseph J. Cullen, Garry R. Buettner. Tumor cells have decreased ability to metabolize H2O2: Implications for pharmacological ascorbate in cancer therapy. Redox Biology, 2016; 10: 274 DOI: 10.1016/j.redox.2016.10.010
  6. Putchala MC, Ramani P, Sherlin HJ, Premkumar P, Natesan A. Ascorbic acid and its prooxidant activity as a therapy for tumours of oral cavity: a systematic review. Arch Oral Biol. 2013;58:563-574
  7. Ströhle A1, Hahn A. Vitamin C and immune function. Med Monatsschr Pharm. 2009 Feb; 32(2):49-54
  8. Maggini S1, Wintergerst ES, Beveridge S, Hornig DH. Selected vitamins and trace elements support immune function by strengthening epithelial barriers and cellular and humoral immune responses. Br J Nutr. 2007 Oct;98 Suppl 1:S29-35.
  9. Candeias SM1, Gaipl US. The Immune System in Cancer Prevention, Development and Therapy. Anticancer Agents Med Chem. 2016;16(1):101-7
  10. Padayatty SJ, Sun H, Wang Y, Riordan HD, Hewitt SM, Katz A, Wesley RA, Levine M: Vitamin C pharmacokinetics: implications for oral and intravenous use. Ann Intern Med 140: 533-537, 2004
  11. Creagan ET, Moertel CG, O’Fallon JR, Schutt AJ, O’Connell MJ, Rubin J, Frytak S: Failure of high-dose vitamin C (ascorbic acid) therapy to benefit patients with advanced cancer. A controlled trial. N Engl J Med 301: 687-690, 1979 Fritz H, Flower G, Weeks L, et al. Intravenous vitamin C and cancer: a systematic review. Integr Cancer Ther. 2014;13:280-300
  12. Moertel CG, Fleming TR, Creagan ET, Rubin J, O’Connell MJ, Ames MM: 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 312: 137-141, 1985
  13. Park S. The effects of high concentrations of vitamin C on cancer cells. Nutrients. 2013;5:3496-3505
  14. Chen Q, Espey MG, Krishna MC, Mitchell JB, Corpe CP, Buettner GR, Shacter E, Levine M: Pharmacologic ascorbic acid concentrations selectively kill cancer cells: action as a pro-drug to deliver hydrogen peroxide to tissues. Proc Natl Acad Sci USA 102: 13604-13609, 2005
  15. Chen Q, Espey MG, Sun AY, Lee JH, Krishna MC, Shacter E, Choyke PL, Pooput C, Kirk KL, Buettner GR, Levine M: Ascorbate in pharmacologic concentrations selectively generates ascorbate radical and hydrogen peroxide in extracellular fluid in vivo. Proc Natl Acad Sci USA 104: 8749-8754, 2007
  16. Deubzer B, Mayer F, Kuci Z, et al. H(2)O(2)-mediated cyto- toxicity of pharmacologic ascorbate concentrations to neu- roblastoma cells: potential role of lactate and ferritin. Cell Physiol Biochem. 2010;25:767-774
  17. Benade L, Howard T, Burk D: Synergistic killing of Ehrlich ascites carcinoma cells by ascorbate and 3-amino-1,2,4,-triazole. Oncology 23: 33-43, 1969
  18. Prasad KN, Hernandez C, Edwards-Prasad J, Nelson J, Borus T, Robinson WA: Modification of the effect of tamoxifen, cisplatin, DTIC, and interferon-alpha 2b on human melanoma cells in culture by a mixture of vitamins. Nutr Cancer 22: 233-245, 1994
  19. Kurbacher CM, Wagner U, Kolster B, Andreotti PE, Krebs D, Bruckner HW: Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Lett 103: 183-189, 1996
  20. Taper HS, de Gerlache J, Lans M, Roberfroid M: Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 40: 575-579, 1987
  21. Anitra C. Carr, Margreet C. M. Vissers, and John S. Cook. The Effect of Intravenous Vitamin C on Cancer- and Chemotherapy-Related Fatigue and Quality of Life. Front Oncol. 2014; 4: 283