Lee Swanson Research Update

Vitamin C Injections Slow Tumor Growth in Mice

Here’s a report I just received from the National Institutes of Health about a groundbreaking vitamin C discovery.

High-dose injections of vitamin C, also known as ascorbate or ascorbic acid, reduced tumor weight and growth rate by about 50% in mouse models of brain, ovarian and pancreatic cancers, researchers from the National Institutes of Health (NIH) report in the Aug. 5 issue of the Proceedings of the National Academy of Sciences. The researchers traced ascorbate’s anti-cancer effect to the formation of hydrogen peroxide in the extracellular fluid surrounding the tumors. 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 mg of vitamin C a day—for example, two oranges and a serving of broccoli—your body prevents blood levels of ascorbate from exceeding a narrow range,” says 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, NIH scientists 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 four 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. The NIH 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. In their laboratory experiments on 43 cancer and five normal cell lines, the researchers discovered that high concentrations of ascorbate had anticancer effects in 75% of cancer cell lines tested, while sparing normal cells. In their paper, the 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) tumors. The ascorbate injections reduced tumor growth and weight by 41 to 53%. In 30% 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.

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