WASHINGTON, Dec 15 (Reuters Health) -- While antioxidants such as vitamins
A and E can be helpful in healthy people, these vitamins may not be good for
cancer patients on chemotherapy. They appear to reduce the effectiveness of
cancer therapy by counteracting the way cancer drugs work, according to a report
presented Monday at the annual meeting of the American Society for Cell Biology.
In particular, vitamins A and E may negatively impact cancer chemotherapy,
said Dr. Rudolph Salganik from the University of North Carolina, Chapel Hill.
"Almost all anticancer drugs kill cancer cells by way of apoptosis," he
said, "and antioxidants like vitamin A and vitamin E dramatically reduce
apoptosis in cancer cells."
Apoptosis is a natural cell suicide program, which causes cells to
self-destruct after they have sustained significant damage to their DNA.
He described experiments in genetically engineered mice that develop brain
tumors. A diet free of vitamins A and E increased the proportion of apoptotic
brain cancer cells from 3% with a normal diet to 19%.
"Cancer patients, especially those receiving chemotherapy or radiation
therapy, might do better on an antioxidant-free diet," Salganik concluded.
The finding may explain the results of previous studies that found higher
rates of lung cancer in smokers who ate diets high in antioxidants, the
researchers suggest.
To further test their findings, Salganik and his team now plan to conduct
studies in humans.
