Vitamin C Impedes Tumor Growth In Mice

High doses of vitamin C (ascorbate) slow tumor growth in mice without harming normal cells, researchers report (Proc. Natl. Acad. Sci. USA 2008, 105, 11105). Michael Graham Espey and Mark Levine of the National Institute of Diabetes & Digestive & Kidney Diseases and coworkers first showed that high levels of ascorbate kill cancer cells in vitro without toxicity to normal cells. The body strictly limits the absorption of ingested ascorbate, but the researchers demonstrated that this barrier can be bypassed in vivo by injecting the compound into tumor-bearing mice. They found that the injected ascorbate serves as a prodrug, leading to formation of free radicals and hydrogen peroxide within tumors. The ascorbate treatments reduced tumor growth and weight by about half and prevented the spread of cancer in the mice without adverse side effects. High doses of ascorbate can also be achieved in people, suggesting that ascorbate or its analogs could be promising anticancer therapeutics, a notion the researchers hope to test in clinical trials.