A new clinical trial tests the effect of high-dose vitamin C in combination with standard treatment on health outcomes for patients with cancer.
The new research was led by scientists at the University of Iowa in Iowa City, and the results were published in the journal Cell Press.
Each infusion raised the patients’ blood levels of vitamin C to 20,000 micromoles (µM). The average level of vitamin C in adults is approximately 70 µM.
Overall, the treatment was tolerated well. The team noted very few minor side effects, such as dry mouth or rare and brief episodes of high blood pressure.
This safety test was the first phase of a series of clinical trials that will investigate whether high-dose vitamin C can effectively increase the lifespan and quality of life for patients that are being treated with chemotherapy and radiation therapy.
For now, the data from the phase I trial show that patients with glioblastoma survived for 4 to 6 months longer than the average survival time noticed in patients who undergo conventional treatment alone. Specifically, patients who also received high doses of ascorbic acid survived for 18 to 22 months compared with 14 to 16 months, which is the typical survival rate for glioblastoma.
The mechanism that might explain the potential efficacy of vitamin C in treating lung and brain cancer relates to the cancer cells’ metabolism.
As a consequence of the faulty metabolism that occurs inside the cancer cells’ mitochondria, these cells produce abnormally high levels of so-called redox active iron molecules. These molecules react with vitamin C and form hydrogen peroxide and hydrogen peroxide-derived free radicals.
Scientists think that these free radicals drive cancer cell death by damaging the cells’ DNA. The free radicals are also thought to weaken the cancer cells and make them more vulnerable to radiation therapy and chemotherapy.
Garry Buettner, study co-author said that “This paper reveals a metabolic frailty in cancer cells that is based on their own production of oxidising agents that allows us to utilise existing redox active compounds, like vitamin C, to sensitise cancer cells to radiation [therapy] and chemotherapy.”
Co-senior author Douglas Spitz also comments on the significance of the findings, “This is a significant example of how knowing details of potential mechanisms and the basic science of redox active compounds in cancer versus normal cells can be leveraged clinically in cancer therapy,” he explains. “Here, we verified convincingly that increased redox active metal ions in cancer cells were responsible for this differential sensitivity of cancer versus normal cells to very high doses of vitamin C.”