The ongoing fight against cancer has featured the usage of various therapies in an effort to discover ones that may eventually lead to cures. The most notable treatments include chemotherapy, immunotherapy, radiation therapy, and surgery; however, other less known treatment options have been shown to be effective in targeting cancer cells. Unfortunately, many of these remain controversial for their lack of consistency and general understanding as to how they work. One such therapy involves the usage of vitamin C.
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While vitamin C has been shown in clinical studies to improve the prognosis of patients with terminal cancer, other studies were unable to reproduce these results. However, this discrepancy could be explained by the difference in administration. Studies that found vitamin C to be beneficial had patients take the compound intravenously, whereas studies that found no such correlation used oral vitamin C supplementation. This difference could be explained by first-pass metabolism, which refers to the detoxification of compounds after administration and occurs when compounds are given orally or within the abdominal cavity, but not when given intravenously. As a result of inconsistent administration in these studies, the amount of vitamin C in the blood was far less in patients who took the compound orally compared to those who took it intravenously; the difference in vitamin C concentrations would explain its effectiveness, or lack thereof, when administered to cancer patients.
Past studies were able to demonstrate the ability of vitamin C to both inhibit the growth of tumors and to produce hydrogen peroxide, which is selectively toxic towards cancer cells. This was reaffirmed by a recent study that demonstrated the inability of tumor cells to metabolize hydrogen peroxide as effectively as normal cells. Hydrogen peroxide is a toxic reactive oxygen species that can cause cellular damage through oxidative stress at certain amounts. In normal cells, hydrogen peroxide can be detoxified by metabolic pathways, but in cancer cells, the toxic compound is unable to be removed and eventually leads to their death. The novelty of this study stems from its identification of the enzyme catalase, which plays an important role in hydrogen peroxide metabolism, as being present in normal cells but lacking in some cancer cells. The researchers believe that the variability in catalase levels in cancer cells can also account for the inconsistency of vitamin C as a cancer therapy; specifically, only cancer cells with low levels of catalase would be susceptible to high dosages of vitamin C.
The results of this study provide further support of vitamin C being an effective cancer therapy. Although it is unlikely that vitamin C can cure cancer, such findings may contribute to the discovery of cures by elucidating the differences between normal and cancerous cells.
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