Vitamin C or Ascorbic Acid (AA) was first implicated as an anti-cancer agent through the research of nobel Prize Winner Dr. Linus Pauling PhD and Dr. Ewan Cameron MD. Their first clinical trial began in 1971 and the results of this and other research was published in the book “Cancer and Vitamin C” in 1979. In their clinical trial they found a four-fold increase in survival time by those individuals treated with 10,000 mg of AA intravenously.
It has been shown that Vitamin C (ascorbic acid/ascorbate) may improve the outcome in cancer through its function in several critical areas:
Vitamin C increases the resistance to infectious agents by improving lymphocyte function, enhancing bactericidal activity, and modulating complement protein thereby strengthening cellular immunity.
Augmentative treatment to medical therapies
Vitamin C may be able to enhance the toxicity of chemotherapy and radiation against cancer cells. The use of chemotherapeutic agents alone in the treatment of cancer often suppresses the immune system and has numerous side effects due to its toxicity to healthy cells.
Slowing the growth or reversing the cancer process
Vitamin C generates large amounts of hydrogen peroxide (H2O2) which acts as a potent free radical and is toxic to cells. Healthy cells produce a 10-100 fold greater content than in tumour cells of an enzyme called catalase. Catalase protects against the effects of H2O2. When Vitamin C is given at correct dosages there is a preferential cytotoxicity of cancer cells with negligible effects to the host. Studies have indicated that the intravenous infusion of ascorbic acid to achieve a plasma concentration of 400 mg/dL is lethal to most tumour cells.
Vitamin C strengthens the integrity of the extracellular matrix. This increases stromal resistance and effectively “walls off” the tumour thus preventing its growth and metastasis.
Why Intravenous Versus Oral Dosing of Ascorbic Acid?
Oral AA is absorbed through the intestinal lumen in an energy and dose dependent process. It rapidly peaks so that at doses over 2g orally less than 20% is actually absorbed. Large quantities of Ascorbic Acid in the intestinal tract bring water with it leading to gastrointestinal discomfort and diarrhea. Research has shown that high doses of vitamin C have significant cyto-toxic effects. These doses can only be achieved in humans by high dose intravenous administration.
Precautions and Potential Side Effects
The side effects experienced with intravenous administration of Vitamin C are infrequent and are generally related to effects that maybe experienced to intravenous treatments in general.
- Therapy is initiated with a small dose infusion and increased gradually to ensure patient tolerance and safety. Die off of cancer cells may occur too quickly if the increase is too rapid.
- Hemolysis (breaking of red blood cells) may occur in doses greater than 25 grams in individuals with a deficiency of glucose-6-phosphate dehydrogenase (G6PD). The presence of this enzyme is assessed initially and if it is not present treatment with high doses is contraindicated.
- Any condition which could be adversely affected by increased fluid is a relative contraindication to treatment. Renal function is assessed prior to treatment.
- Those who are predisposed to the frequent formation of oxalate kidney stones maybe unable to take Vitamin C intravenously.
- As with any intravenous treatment, localized pain may occur at the infusion site if the rate is too rapid or if intravenous fluid infiltrates into the surrounding tissue. These effects are easily and quickly remedied as necessary.
The Mechanism of Action of Vitamin C in Cancer
Vitamin C is an important extracellular anti-oxidant and plays a role in a host of biochemical reactions in the body. Vitamin C has been validated as supportive therapy in Case studies, Preclinical trials and cancer cell research. The results of these studies show that vitamin C acts in the following ways:
- Selective Cytotoxicity (cancer cell killing) Effect
Vitamin C in high doses leads to the production of large amounts of hydrogen peroxide in the connective tissue of the body. Hydrogen peroxide is an important oxidative molecule involved in many immune reactions in the body. In healthy cells, the hydrogen peroxide is absorbed and then quenched with intra-cellular anti-oxidants, but in cancer cells they often lack sufficient levels of anti-oxidants so hydrogen peroxide will build up. As levels of hydrogen peroxide rise in cancer cells they eventually go through apoptosis (programmed cell death).
- Inhibition of Tumour Growth and Metastasis
Most tumours require the activity of various enzymes in order to invade and metastasize. Ascorbic Acid inhibits the activity of these enzymes and promotes the production of collagen which may play a role in stabilizing the tumour and preventing local tissue invasion.
Ascorbic Acid has been tested in tissue cultures and animal models in combination with many different chemotherapeutics to evaluate a combined effect on tumours. Most well designed trials have shown a generally positive enhancement of chemotherapeutic success in studies where chemotherapy is combined with Ascorbic Acid.