Vitamin C Linked to Cancer Drug Ineffectiveness

by Debbie Marsh

If you’re taking vitamin C supplements while undergoing chemotherapy, chances are you should stop. According to a new study led by Dr. Mark Heaney at Memorial Sloan-Kettering Cancer Center in New York, vitamin C reduced the effectiveness of chemotherapy drugs in animal studies by 30 – 70 percent.

Heaney and his team tested a wide variety of drugs – both those that produce oxygen-free radicals and others that don’t – on cancer cells. They found that the ability of every drug, including Adriamycin, Platinol, Oncovin, methotrexate and Gleevec, to battle the cancer cells was substantially reduced.

Vitamin C is an antioxidant, and some previous researchers encouraged its use by cancer patients to maintain general good health. In the study, however, it appeared that the vitamin protects mitochondria, which normally serve as the power plant of the cells. Chemotherapy drugs target mitochondria in cancer cells, attempting to weaken them enough to send a signal to the cell to die.

The study group, which included researchers from Columbia University, found that tumors in mice pretreated with Vitamin C grew more rapidly than those that didn’t contain the vitamin. Previous research at Sloan-Kettering showed that the vitamin appears to accumulate more quickly in cancer cells than in normal ones.

Heaney noted that healthy cells probably do benefit from the effect of the vitamin and cancer patients should eat a balanced diet, including foods rich in vitamin C. Its large supplemental doses of the antioxidant that are troublesome, he said.

Read more
For further information: “Vitamin C Antagonizes the Cytotoxic Effects of Antineoplastic Drugs,” by Heaney, Mark L.; Gardner, Jeffrey R.; Karasavvas, Nicos; Golde, David W., Scheinberg, David A.; Smith, Emily A.; and O’Connor, Owen A., Cancer Research, Oct. 2008, 68: 8031-8038.