Intravenous Vitamin C for Cancer Therapy – Identifying the Current Gaps in Our Knowledge

Abstract

The use of intravenous vitamin C (IVC) for cancer therapy has long been an area of intense controversy. Despite this, high dose IVC has been administered for decades by complementary health care practitioners and physicians, with little evidence base resulting in inconsistent clinical practice. In this review we pose a series of questions of relevance to both researchers and clinicians, and also patients themselves, in order to identify current gaps in our knowledge. These questions include: Do oncology patients have compromised vitamin C status? Is intravenous the optimal route of vitamin C administration? Is IVC safe? Does IVC interfere with chemotherapy or radiotherapy? Does IVC decrease the toxic side effects of chemotherapy and improve quality of life? What are the relevant mechanisms of action of IVC? What are the optimal doses, frequency, and duration of IVC therapy? Researchers have made massive strides over the last 20 years and have addressed many of these important aspects, such as the best route for administration, safety, interactions with chemotherapy, quality of life, and potential mechanisms of action. However, we still do not know the answers to a number of fundamental questions around best clinical practice, such as how much, how often and for how long to administer IVC to oncology patients. These questions point the way forward for both basic research and future clinical trials.

Vitamin C promotes the proliferation and effector functions of human γδ T cells

“…Several studies have demonstrated that L-ascorbic acid/VC, in addition to its role in cancer treatment, [35][36][37][38] promotes mammalian cell differentiation and DNA synthesis. 6,27,30,32 However, the impact of VC on the differentiation and effector function of human γδ T cells has not been addressed to date.…”

“…L Kouakanou et al to be investigated if additional features of Vγ9Vδ2 T cells, such as their capacity for B cell help 50 or antigen cross-presentation, 51 are also modulated by VC. Finally, given that VC can also be easily administered in high concentrations in vivo, 35 it might also be considered to support γδ T cell-based immunotherapy with the in vivo application of VC.…”

Vitamin C versus Cancer: Ascorbic Acid Radical and Impairment of Mitochondrial Respiration?

“…In fact, reported concentrations of vitamin C in cells under normal conditions are significantly higher than those of cytochrome c (~10-30 nmol/mg protein versus~0.1-1 nmol/mg protein) [90,92]. In this case, ascorbate and AFR concentrations in cancer cells after treatment with high doses of vitamin C should be much higher than cytochrome c concentrations [93]. This supports the possibility of direct electron transfer from AFR to cytochrome c at Complex IV.…”

Pro- and Antioxidant Effects of Vitamin C in Cancer in correspondence to Its Dietary and Pharmacological Concentrations

“…These problems belong to fundamental aspects of anticancer therapy with high doses of vitamin C that were recently addressed in an excellent review by Carr and Cook [6]. These authors concluded that cancer patients had lower concentration of vitamin C than healthy control, intravenous infusion is the optimal route of administration of high doses of this vitamin, and this is a patient-safe procedure.…”

“…Anticancer properties of vitamin C have been reviewed in several recent papers (e.g., [4,[6][7][8][9][10]). These studies suggest several potential targets of anticancer action of vitamin C-some of them will be described and referenced in the next sections.…”