Study shows vitamin C's cancer-fighting properties

By Will Dunham

WASHINGTON (Reuters) - Vitamin C can impede the growth of some types of tumors although not in the way some scientists had suspected, researchers reported on Monday.

The new research, published in the journal Cancer Cell, supported the general notion that vitamin C and other so-called antioxidants can slow tumor growth, but pointed to a mechanism different from the one many experts had suspected.

The researchers generated encouraging results when giving vitamin C to mice that had been implanted with human cancer cells -- either the blood cancer lymphoma or prostate cancer. Another antioxidant, N-acetylcysteine, also limited tumor growth in the mice, the researchers said.

Antioxidants are nutrients that prevent some of the damage from unstable molecules known as free radicals, created when the body turns food into energy. Vitamin C, vitamin E and beta-carotene are among well-known antioxidants.

Previous research had suggested that vitamin C may stifle tumor growth by preventing DNA damage from free radicals.

But researchers led by Dr. Chi Dang, a professor of medicine and oncology at Johns Hopkins University in Baltimore, found that antioxidants appear to be working in a different way -- undermining a tumor's ability to grow under certain conditions.

Figuring out how antioxidants impede tumors should help scientists figure out how they might be harnessed to fight cancer, Dang said. In addition to the cancer types involved in this study, others that might be vulnerable to vitamin C include colon cancer and cervical cancer, he said.

Dang said more research is needed and cautioned against taking high doses of vitamin C based on these findings.