High-dose injections of vitamin C, also known as ascorbate or ascorbic acid, can stop the spread of cancer and slow the growth of tumours by 50 percent in lab mice tests.

In a study in Tuesday's issue of the Proceedings of the National Academy of Sciences, researchers from the National Institutes of Health (NIH) injected ascorbate into the veins or abdominal cavities of rodents with aggressive brain, ovarian, and pancreatic tumors," delivering "up to four grams per kilogram of body weight daily."

The researchers, however, 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 tumor cells.

By injecting mice with 43 cancer and five 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.

Scientists involved with the study also pointed to evidence that "these high ascorbate concentrations could be achieved in people."

Vitamin C, which is found in fruit and vegetables, plays a critical role in health, and a prolonged deficiency leads to scurvy and eventually to death. It may also act as an antioxidant, protecting cells from the damaging effects of free radicals.

Vitamin C was considered as a possible treatment for cancer three decades ago, but fell out of favour when studies where the vitamin was given orally failed to live up to expectations.

(Agencies via Xinhua August 5, 2008)