Cancer researchers in the US are currently studying the effects of treatment combining chemotherapy or radiotherapy with high doses of vitamin C administered intravenously. The first results, focusing on lung cancer and pancreatic cancer the two of the disease's most deadly forms -- appear to be encouraging.
Vitamin C levels in the blood can be 100 to 500 times higher when administered intravenously, researchers from the University of Iowa, USA, explain in a study published in Redox Biology.
This super-high concentration of vitamin C in the blood is understood to be crucial in its ability to fight cancer cells.
Vitamin C, or ascorbic acid, is an antioxidant compound found in a wide range of fruit and vegetables (oranges, grapefruits, lemons, cabbages). It can also be taken as a dietary supplement, either alone or as part of a multivitamin complex.
A preliminary clinical trial, involving lung cancer and pancreatic cancer patients, saw initial encouraging results when combining high-dose intravenous vitamin C with chemotherapy or radiotherapy. The overall health of patients was found to improve and the treatment was well tolerated.
The scientists established that vitamin C breaks down to form hydrogen peroxide (H2O2) that can damage DNA and tissue.
The study reveals that unlike "normal" cells, cancer cells have difficulty removing hydrogen peroxide, and can struggle to survive its effects. This phenomenon explains how very high levels of vitamin C, used in the clinical trials, can effectively attack cancer cells.
According to the study, hydrogen peroxide doesn't appear to be harmful to healthy, non cancerous cells, which contain an enzyme called catalase that allows them to keep levels of hydrogen peroxide, caused by the decomposition of vitamin C, very low by removing it.
"Our results suggest that cancers with low levels of catalase are likely to be the most responsive to high-dose vitamin C therapy, whereas cancers with relatively high levels of catalase may be the least responsive," said Garry Buettner, professor of radiation oncology at the University of Iowa.
The researchers now hope to establish whether this kind of treatment can improve survival rates for cancer patients.