University of Iowa (UI) researchers believe that they have found out why the use of vitamin C as cancer therapy has had issues in the past. The UI scientists have shown that giving vitamin C intravenously, rather than the traditional method of administering it orally, can bypass the gut metabolism and excretion pathways and result in blood levels that are 100 to 500 times higher than levels seen with oral ingestion. It is this super-high concentration in the blood that is crucial to vitamin C’s ability to attack cancer cells.

Earlier phase 1 trials by UI redox biology expert Garry Buettner indicated that combining high-dose, intravenous vitamin C with standard chemotherapy or radiation is safe and well-tolerated and hinted that the therapy improves patient outcomes. In a new study published recently in the December issue of the journal Redox Biology, Buettner and his colleagues have homed in on the biological details of how high-dose vitamin C kills cancer cells.

The study shows that vitamin C breaks down easily, generating hydrogen peroxide, a so-called reactive oxygen species that can damage tissue and DNA. The study also shows that tumor cells are much less capable of removing the damaging hydrogen peroxide than normal cells.