Vitamin C has long been known for its effects on immune stimulation and function. Because of vitamin C’s role in maintaining normal immune function, many people use it for treating and preventing infectious conditions such as the common cold. Activity of several major immune cells and the messengers they produce seem to be increased by vitamin C. An additional viewpoint is that vitamin C serves as an antioxidant and increased intake from either foods or dietary supplements may promote good health.
Cancer chemoprevention studies i.e., studies that have looked at the use of chemical agents, drugs, or food supplements to prevent the development of cancer, have used this antioxidant rationale to examine any association between decreased tumor incidence and Vitamin C ingestion. Unfortunately, these studies have not revealed tumor reduction with use of ORAL vitamin C. In contrast to this line of investigation, there is also the hypothesis that high doses of intravenous Vitamin C may create a pro-oxidant or “cell-killing” state within tumors and possibly improve quality of life.
Evolving research speaks to this hypothesis and the use of vitamin C, intravenously, as a cancer fighter. So far, high dose vitamin C has been tested in phase I clinical trials in patients with advanced cancer and was found to be safe and well tolerated. If given at high enough doses Vitamin C is capable of turning into hydrogen peroxide within cancer cells causing these cells to die and thereby promoting tumor regression and improving quality of life.
Research continues to elucidate the mechanism behind pharmacologic concentrations of ascorbic acid and its cytotoxic effects. It has been found that administration of high dose ascorbic acid results in the formation of the ascorbate radical and H2O2 in the extracellular fluid of the tissue parenchyma (spaces around the cells). This production of H2O2 has the ability to degrade DNA integrity, disrupt glucose metabolism and compromise cell membranes in susceptible cells (cancer cells.) Studies support the idea that this production of hydrogen peroxide leads to oxidative stress and subsequent necrotic death of cancer cells and spares healthy cells.
Additional benefits of IV Vitamin C include the promotion of healthy mitochondria function, stimulation of the immune system to produce interferon, increase NK cell numbers, and an increase in phagocytosis (the destruction and ingestion of cancer cells my the immune system) with enhanced migration and killing function. Vitamin C also reduces oxidative damage to the p53 (apoptosis-regulating) gene due to chemo and radiation. This helps prevent the DNA damage and mutation that would otherwise render cancer cell apoptosis and death nonfunctional.
There are now multiple studies underway showing tumor reduction and improved survival with high dose ascorbic acid using pharmacologic doses (intravenous administration.)
Vitamin C is well absorbed by tablet or capsule at low doses, but the absorption of vitamin C decreases as the dose increases. Approximately 87% of a 30 mg oral dose is absorbed, 80% of a 100 mg dose is absorbed, 63 % of a 500 mg dose is absorbed, and less than 50% of a 1250 mg does is absorbed. Most of what is absorbed is excreted in the urine. Decreased absorption with increasing dose and increased excretion in the urine limits the ability of the blood plasma to become high in Vitamin C.
Research in this field has shown that high blood plasma levels of vitamin C allow the nutrient to be carried to the area where tumors exist in the body. When given intravenously, it is possible to elevate blood plasma levels of antioxidant Vitamin C over longer periods of time which may fight cancer and produce health benefits.
It is important to note that normal levels of Vitamin C are important. These levels function to block free radical generation and maintain the oxidation reduction reaction intracellularly; i.e., its principle action is as an anti-oxidant. However, to act as a pro-oxidant, cancer fighter, intravenous administration is imperative.
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