Sunday Nov 24, 2013 (foodconsumer.org) -- A study in Oncology Reports suggests that taking vitamin C or ascorbate as a dietary supplement or administration of vitamin C through an intravenous injection may not interfere with radiotherapy intended to treat cancer and instead it boosts the efficacy of radiotherapy.

Vitamin C is an antioxidant and some alternative clinicians claim vitamin C in high doses can help treat cancer without causing any side effect.  But some doctors caution that antioxidants may scavenge reactive oxygen species (ROS) generated by radiation to kill cancer cells and reduce the efficacy of radiotherapy.

S. Terashima from Hirosaki University Graduate School of Health Sciences in Hirosaki, Aomori, Japan and colleagues conducted the study and found evidence suggesting that vitamin C as an antioxidant actually can help kill cancer cells when used together with radiotherapy.

For the study, the Japanese scientists applied 2.5 mM vitamin C to HL-60 human promyelocytic leukemia cell culture and then irradiated the cells in a dose of 2 Gy.  This treatment resulted in an additive cytotoxic effect against leukemia cells, meaning that vitamin C helps the treatment.

The scientists also found that with the presence of catalase, which can neutralize H2O2 and prevent cells from being damaged by ROS, vitamin C alone in the cancer cell culture does not induce a cytotoxic effect.

Also vitamin C alone and the combination of radiation and vitamin C actually reduced the intercellular ROS, but only slightly when catalase was present.  When the cell cluture was treated with the combination of vitamin C and radiation, mitochondrial membrane potential was decreased and apoptosis or programmed cell deaths was increased, meaning a higher efficacy resulted from the combinational treatment.

The findings suggest that vitamin C does not reduce the efficacy of radiotherapy, but actually helps radiotherapy to kill the leukemia cells.  Vitamin C contributes to the cytotoxic effect because it helps lower the cell membrane potential and increase apoptosis.

The study concluded "a combination of AsA (ascorbate) with radiation treatment is effective in cancer therapy when considering ROS in cancer cells." (David Liu, PHD)