Vitamins may thwart cancer-fighting efforts

December 14, 1999
Web posted at: 5:01 PM EST (2201 GMT)

In this story: Unanticipated results Diet and cancer: A new approach RELATEDS

By Camille Mojica Rey

(WebMD) -- Vitamins are thought by many to be a key weapon in the arsenal of disease prevention. But when it comes to cancer, new research presented Monday at the American Society for Cell Biology's annual meeting in Washington, D.C. suggests that using vitamins can backfire, actually helping the disease spread more quickly.

Vitamins A and E, in particular, may interfere with the natural mechanism by which defective or cancerous cells self-destruct, causing concern among researchers who say that cancer patients who pop vitamins during chemotherapy and radiation therapy may unwittingly be sabotaging their own treatment.

"Everyone believes vitamins are very important," said lead researcher Rudolph Salganik, PhD, of the University of North Carolina research team. "The truth is we don't know how useful vitamins are for us."

In the experiments by Salganik and his colleagues, vitamins A and E proved damaging to mice with brain tumors. Mice who were deprived of all but the smallest traces of these vitamins had tumors that were 17 percent smaller than those with normal amounts of the vitamins in their diet. The vitamin-deficient mice also had five times the number of dying cells in their tumors.

Unanticipated results

"Frankly, we didn't believe the results at first," Salganik said.

But the experiments were repeated in the mice, yielding the same results. Preliminary data, also presented by Salganik at the meeting, shows the same trend in mice with breast cancer.

The results may be surprising, but make logical sense on a cellular level, Salganik said. In the body's normal housekeeping, he explained, oxygen in the blood reacts with cells and causes them to die. Antioxidants like vitamins A and E combine with these free oxygen radicals, taking them out of commission and keeping them from killing off cells.

When these free radicals are removed from the bloodstream, healthy cells benefit. But cancerous cells, whose growth is already out of control, benefit as well: The lack of free radicals means even less control over the unchecked growth.

"If you suppress free radicals, you suppress programmed cell death," Salganik said.

Diet and cancer: A new approach

So far most of the research on diet and cancer has focused on preventing the disease in healthy people, said Charles Fuchs, MD, a researcher and oncologist specializing in colon cancer treatment at Harvard University's Dana Farber Cancer Institute.

But Fuchs said physicians don't know much about the diet's affect on cancer once it's diagnosed. Studies on humans and animals so far have shown inconsistent results, making it hard to draw conclusions.

"Frankly, the answers are much less clear," he said. "We can speculate, but we don't know.

"What we need to do is study this in people, and we have to look at each individual cancer. It's naive to think that what's good for one cancer is good for another."

Fuchs and his colleagues are planning a study in which they will track colon cancer patients from diagnosis to recovery to examine the relationship between their diets and supplement use and their progress.

On the other hand, Salganik said he would like to collaborate with clinical researchers to repeat his mice experiments on humans, specifically controlling the amounts of vitamins cancer patients receive.

RELATEDS AT :

Overview of dietary supplements
Vital vitamins

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RELATED SITES:

American Society for Cell Biology
The University of North Carolina
Dana Farber Cancer Institute

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