Washington, Aug 5 (ANI): In a new study, high-dose injections of vitamin C - also known as ascorbate or ascorbic acid - were found to reduce the size of tumours and slow cancerous growths by about 50 percent in laboratory mice.
Researchers at the National Institutes of Health noted the phenomenon in brain, ovarian and pancreatic cancers.
The researchers traced ascorbate’’s anti-cancer effect to the formation of hydrogen peroxide in the extracellular fluid surrounding the tumours. Normal cells were unaffected.
Natural physiologic controls precisely regulate the amount of ascorbate absorbed by the body when it is taken orally.
“When you eat foods containing more than 200 milligrams of vitamin C a day–for example, 2 oranges and a serving of broccoli–your body prevents blood levels of ascorbate from exceeding a narrow range,” said Mark Levine, M.D., the study’’s lead author and chief of the Molecular and Clinical Nutrition Section of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of the NIH.
To bypass these normal controls, researchers injected ascorbate into the veins or abdominal cavities of rodents with aggressive brain, ovarian, and pancreatic tumors.
By doing so, they were able to deliver high doses of ascorbate, up to 4 grams per kilogram of body weight daily.
“At these high injected doses, we hoped to see drug-like activity that might be useful in cancer treatment,” said Levine.
Vitamin C plays a critical role in health, and a prolonged deficiency leads to scurvy and eventually to death. Some proteins known as enzymes, which have vital biochemical functions, require the vitamin to work properly.
Vitamin C may also act as an antioxidant, protecting cells from the damaging effects of free radicals.
However, the researchers tested the idea that ascorbate, when injected at high doses, may have prooxidant instead of antioxidant activity.
Prooxidants would generate free radicals and the formation of hydrogen peroxide, which, the scientists hypothesized, might kill tumour cells.
In their laboratory experiments on 43 cancer and 5 normal cell lines, the researchers discovered that high concentrations of ascorbate had anticancer effects in 75 percent of cancer cell lines tested, while sparing normal cells.
Researchers also showed that these high ascorbate concentrations could be achieved in people.
The team then tested ascorbate injections in immune-deficient mice with rapidly spreading ovarian, pancreatic, and glioblastoma (brain) tumours.
The ascorbate injections reduced tumour growth and weight by 41 to 53 percent. In 30 percent of glioblastoma controls, the cancer had spread to other organs, but the ascorbate-treated animals had no signs of disseminated cancer.
“These pre-clinical data provide the first firm basis for advancing pharmacologic ascorbate in cancer treatment in humans,” the researchers conclude.
The study is published in the August 5, 2008, issue of the Proceedings of the National Academy of Sciences. (ANI)