BEIJING, Sept. 13 (Xinhuanet) -- High doses of vitamin C injected into the bloodstream can fight cancer -- at least in the laboratory, researchers report.

    Scientists found that vitamin C in the form of ascorbate killed cancer cells in the laboratory. But the effective dose was so high it could only be delivered by infusion into the blood.

    The findings appear to contradict earlier studies showing no cancer benefit from vitamin C. However, the researchers point out that those trials only investigated orally taken vitamins.

    Earlier work in the 1970s which used both intravenous and oral ascorbate had hinted at an anti-cancer effect. 

    After those initial, failed studies using oral vitamin C, "the conclusion was that this therapy should be shelved, that it doesn't work," said lead researcher Dr. Mark Levine, chief of the molecular and clinical nutrition section and senior staff physician, National Institute of Diabetes & Digestive & Kidney Diseases.

    As part of those studies they examined the body's absorption of the nutrient and found that while oral intake does reach a saturation point, "when you give doses intravenously they go through the roof in the blood and then they are cleared," lead researcher Dr. Mark Levine, chief of the molecular and clinical nutrition section and senior staff physician, National Institute of Diabetes & Digestive & Kidney Diseases explained.

    According to Levine, a 10 gram dose of vitamin C given intravenously produces bloodstream concentrations more than 25-fold higher than concentrations achieved from the same oral dose.

    A study published in the Sept. 12-16 issue of the Proceedings of the National Academy of Sciences suggested vitamin C led to the formation of hydrogen peroxide, a chemical that can kill cells. This suggests a potential mechanism for therapy, Levine said.

    "The mechanism has to be validated in animals -- the effects tested in animals to see if this is true," he said. Enditem

    (Agencies)