Vitamin C, cancer and chemotherapy treatment is either a good or bad combination, depending on the research that’s making news.

Since this essential vitamin is known to be an antioxidant, many experts suggest it may help in the fight against cancer. But when chemotherapy drugs are involved, vitamin C may not be the supplement to use, according to a team of New York scientists whose findings are soon to appear in the journal Cancer Research.

The work, conducted in the test tube and on live mice, showed that levels of vitamin C reduced the effectiveness of some cancer drugs. These drugs are known to produce oxygen free radicals that are meant to kill the cancer cells.

If you supplement with vitamin C while taking these medications, the vitamin C is suspected of soaking up the free radicals intended for the cancer cells — letting them continue to live and grow.

“What we found is that vitamin C blunted the effectiveness of all the chemotherapy drugs we studied,” says Mark Heaney, MD, PhD, associate attending physician at Memorial Sloan-Kettering Cancer Center and the study’s lead author. “What vitamin C does is protect the cancer cells from the chemotherapy mainly by protecting their mitochondria [the cell’s power sources],”

Chemotherapy medications are meant to damage the mitochondria in the cancer cells, signaling the cell to die.

Here’s how the research was done. The team pretreated some leukemia and lymphoma cells (and did not treat others) with the form vitamin C takes when it enters a cell. Both sets of cells were then exposed to a range of chemo drugs including Adriamycin, Platinol, Oncovin, methotrexate and Gleevec. The effects were then measured and a 30% to 70% cut in effectiveness was observed.

Chemotherapy just was not as effective.

Next, the cancer cells were implanted into mice. Here the tumors pretreated with vitamin C grew more quickly than those that had not been exposed to the vitamin.

It seems that just like healthy cells, cancer cells might be able to benefit from the protective effects of vitamin C. The team felt that the buildup of vitamin C levels in cells was similar to what would result if a patient took large doses of vitamin C supplements.

The idea that vitamin C could be used to treat cancer was first put forward in the 1970s by American scientist Linus Pauling, awarded the Nobel Prize for chemistry in 1954. Still the link wasn’t born out by three separate Mayo Clinic studies during the 1980s — all well designed, controlled, double blind experiments.

However, although the recent study seemed damning cancer expert, Balz Frei, PhD. the director and chair of the Linus Pauling Institute, looked at the work of the New York researchers, and mentioned some problems with the study:

– Doses of vitamin C used were very high.
– Mice produce vitamin C naturally, and even more when they are ill.
– Only leukemia and lymphoma cancers were studied.
– Only some chemotherapy agents were studied.

Frei continues to believe that very high concentrations of vitamin C, as the late Linus Pauling advocated, could well prove toxic to cancer cells. He does admit that vitamin C may be contra-indicated during some types of chemo. And while the New York researchers may discourage vitamin C supplements during chemotherapy, Frie believes that in daily doses up to 500mg it can be more helpful than harmful.

In the meantime, all sides agree that more study is needed. The recommended intake of vitamin C is 75 milligrams for women, 90 for men. Supplements come in many forms, but natural sources are always best… especially if you are undergoing chemotherapy treatment for cancer. If you’re using any of the drugs used in the study, talk with your own doctor about how much vitamin C is right for you.