A new study by scientists in the United States has revealed that vitamin C may blunt the effectiveness of chemotherapy treatment.
In pre-clinical studies, cancer researchers at Memorial Sloan-Kettering Cancer Center in New York have found that vitamin C appears to substantially reduce the effectiveness of anticancer drugs.
The study found that when human cancer cells were treated with a form of vitamin C in lab dishes, chemotherapy drugs killed 30% to 70% fewer tumour cells than usual and they say the same mechanism may affect patient outcomes as vitamin C supplements may undercut the effectiveness of cancer drugs.
The team led by Dr. Mark Heaney also implanted human cancer cells into mice, and found that when mice were given vitamin C supplements two hours before chemotherapy, the tumours grew more quickly.
The research team, which included researchers from Columbia University, then delved into the mechanism by which vitamin C may be protecting these cells and discovered that it was not because the nutrient was neutralizing oxygen-free radicals.
Five commonly used chemotherapy drugs doxorubicin, cisplatin, methotrexate, vincristine and Gleevec, also known as imatinib, were tested and Dr. Heaney says while the vitamin C did not neutralize the effects of the chemotherapy drugs, it blunted their effects.
The drugs work in different ways to combat tumours and Dr. Heaney says while vitamin C is something everyone needs to have in their diet, he does not recommend taking supplemental vitamin C during chemotherapy treatment and it is the use of large doses of over-the-counter vitamin C that is a concern.
Dr. Heaney believes the protective effect vitamin C has on mitochondria, which generate energy for a cell within cancer cells, may be the culprit rather than the antioxidant properties of the vitamin.