Whether vitamin C (ascorbate) has a role to play as an anti-cancer agent has been debated for decades. Ascorbate has been used by cancer patients in an unregulated environment, either as a dietary supplement or in pharmacological doses administered by infusion, with numerous reports of clinical benefit, but in the absence of rigorous clinical trial data. The design of appropriate clinical trials has been hindered by a lack of understanding of the mechanism(s) of action that would inform the choice of effective dose, timing of administration and likely responsive cancer models. More recently, expanded understanding of the biological activities of ascorbate has led to a number of plausible hypotheses for mechanisms of anti-cancer activity.
Recent discoveries have expanded our knowledge of the biological functions of ascorbate, and have highlighted a number of interesting hypotheses that suggest there is a good rationale to investigate the feasibility of using ascorbate as an adjunct treatment for cancer. We believe that the research progress described in this review will soon lead to the development of effective protocols for the use of ascorbate in the cancer clinical setting. Clinical studies underway will help identify which patients might benefit from ascorbate treatment. Given its lack of toxicity, ready availability and low cost, it is our hope that good information on the mechanism(s) of action will aid translation of the new information into clinical practice.