Scientists continue to debate the health impacts of vitamin C, which is one of the most popular health supplements on the market

Boston [06.25.01] -- Millions of Americans take vitamin C to protect their body's cells from cancer, spending $500 million every year on the supplement. But new research seems to indicate that the popular vitamin could actually cause cancer in the cells it's taken to protect. Should consumers be cautious?

   Yes and no, says Tufts' Jeffrey Blumberg, a world-renowned expert on antioxidants like vitamin C.

   According to Blumberg, findings about the vitamin's possible effect on cells are not new. "This is quite consistent with what we know about the chemical nature of vitamin C," Blumberg told the Reuters international news service.

   But that doesn't mean consumers should stop taking the vitamin as a dietary supplement, the Tufts expert said.

   "You have to be careful about using [these findings] to make conclusions about how much vitamin C a person should consume," he told Reuters.

   The reason, said Blumberg, is that dietary recommendations should be based on the vitamin's biological, not chemical properties.

   "This was an experiment done in the lab, not in the biological context," Blumberg told the LA Times.

   To date, the Tufts expert said many studies have been done on the popular supplement, but they haven't shown it to be harmful. "The first thing to point out is that there's no good evidence that vitamin C supplements are actually causing cancer in anyone," he told Reuters.

   Many scientists suggest that vitamin C's antioxidant properties actually protect cells from cancer.

   "A significant number of students have shown vitamin C to either have no effect or a positive impact on DNA, Reuters reported.

   But Blumberg cautions that consumers shouldn't over use the vitamin. People with really good diets -- who get about 200 milligrams of vitamin C through fruits and vegetables each day -- should avoid an extra vitamin C supplement, Blumberg told the international wire service.