Vitamin C: Epigenetic roles and cancer

Vitamin C, which exists predominantly as ascorbate anion under physiological pH conditions, is an essential micronutrient for humans. Inadequate vitamin C consumption, certain genetic variation in transporters, and cancer-associated oxidative stress may collectively contribute to the intracellular vitamin C deficiency in cancer cells. In addition to being a well-known antioxidant, vitamin C serves as cofactor for various functionally important enzymes such as ten-eleven translocation methylcytosine dioxygenase and hypoxia-inducible factor-1α hydroxylase. Due to the pivotal role of these enzymes in cancer, compensation for the intracellular vitamin C deficiency is implicated in therapeutic potentials for cancer treatment. Furthermore, vitamin C is also considered as a prodrug to deliver free radicals to preferentially damage cancer cells by intravenous infusion of high doses. Although using vitamin C to treat cancer has a long controversial history, the recently uncovered function of vitamin C in regulating the demethylation of DNA and histone likely revitalizes the hope for this easily accessible and inexpensive vitamin in cancer patient care.