Intravenous Vitamin C for Cancer Therapy Q&A

Vitamin C has essential functions within the body, including vital roles in many anti-cancer mechanisms (Du et al., 2012).Treatment of cancer is thought to require much higher doses of vitamin C than normal dietary intakes (Parrow et al., 2013). In fact, high dose intravenous vitamin C (IVC) has been administered by physicians for many years as an Integrative therapy for oncology patients (Padayatty et al., 2010)

Over the last 20 years, researchers have addressed many of Vitamin C’s important aspects in Cancer patients , such as the best route for administration, safety, interactions with chemotherapy, quality of life, and potential mechanisms of action.

How much, how often and for how long to administer IVC to oncology patients?

Anitra C. Carr and John Cook in a 2018 review tried to identify the current  gap of knowledge about what we know about Intravenous Vitamin C

Do oncology patients have compromised vitamin C status?

Yes, studies consistently show that patients with cancer have lower mean circulating vitamin C levels than healthy volunteers. Cancer patients have higher rates of Vitamin  C deficiency. Increasing the vitamin C status of oncology patients is likely to be of benefit.

Is IV the optimal route for vitamin C administration?

Yes, IV administration of vitamin C can provide significantly higher peak plasma concentrations because it bypasses the regulated intestinal uptake of oral vitamin C. These higher concentrations are believed to be required for some of the proposed anti-cancer mechanisms of vitamin C and may also enhance diffusion of the vitamin into the hypoxic core of solid tumors.

Is IVC safe?

Yes, IVC is remarkably safe, considering the massive (50-75 g) doses that are often administered. However,  caution is warranted in patients with impaired renal function due to their inability to adequately clear high IVC doses from circulation, and patients with G6PD deficiency due to inability to detoxify oxidative stress generated by high dose IVC administration. Caution is also required for patients requiring regular glucose monitoring due to the potential for IVC to interfere with glucose monitors.

Does IVC interfere with chemotherapy or radiotherapy?

Clinical trials indicate that IVC does not adversely interfere with chemotherapy and pre-clinical studies indicate that it may in fact act synergistically in combination with different chemotherapeutic agents. There is as yet limited research around interference with radiotherapy, with conflicting results likely due to the timing of the interventions.

Does IVC decrease the toxic side effects of chemotherapy and improve quality of life?

Both pre-clinical and clinical studies indicate that IVC can decrease the  toxicity of chemotherapeutic agents, likely through its antioxidant and anti-inflammatory activities, without affecting the anti-cancer activities of the chemotherapeutic agents. The reduction in specific chemotherapy-related side-effects results in an overall improvement in the health-related quality of life of oncology patients.

What are the optimal doses, frequency, and duration of IVC therapy?

There is still little consensus as to how much, how often and for how long to administer IVC to oncology patients. Higher doses (>50 g/d) being required for some anti-cancer mechanisms, and lower doses (≤10 g/d) being sufficient for decreasing symptoms and improving quality of life. It is possible that antitumor activity may require long term treatment and follow-up, e.g., over years rather than just the few weeks or months of most clinical trials.

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