High-dose vitamin C makes cancer treatment more effective, trial shows
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In the 1970s and 1980s, Nobel Prize winner Linus Pauling, together with surgeon Ewan Cameron, first hypothesized the clinical benefits of vitamin 100 for treating people with cancer .
Since then, further studies in animals and cancer cell cultures suggested that a high concentration of ascorbic acid might prevent and treat cancer.
More recent studies have examined the combined effect of high-dose vitamin C and conventional cancer treatment. Some of this research showed that patients who received the combined treatment had a slower progression of the disease, while others have suggested that the side effects of chemotherapy were less pronounced among those who also took high doses of vitamin C.
To obtain a high dose in these studies, vitamin C is usually administered using intravenous infusion. Vitamin C has a short half-life of only 2 hours in the human body, which is why it must be administered in high doses as a treatment.
A new clinical trial studies the effect of giving between 800 and 1,000 times the daily recommended dose of vitamin C to patients with brain and lung cancer.
The new research was led by scientists at the University of Iowa in Iowa City, and the results were published in the journal Cancer Cell.
As part of the human safety trial, 11 patients with brain cancer who were undergoing standard chemotherapy and radiation therapy were also administered three weekly intravenous infusions of vitamin C for 2 months, and then two weekly infusions for 7 months.
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.
For the upcoming phase II of the clinical trials, the scientists will examine the effects of vitamin C in participants with stage 4 lung cancer as well as in those with highly aggressive brain tumors, such as glioblastoma.
How vitamin C weakens cancer cells
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.
