High-dose antioxidant supplements, such as vitamins C and E, may raise cancer risks

-- Jeff Muise

Thursday, May 13, 2010 (Last Updated: 05/14/2010)

THURSDAY, May 13 (HealthDay News) -- Taking excessive amounts of antioxidants, such as high-dose supplements of vitamin C and E, can increase genetic abnormalities in cells, which may raise the risk for developing cancer, according to a study published online May 4 in Stem Cells.

Tao-Sheng Li, M.D., and Eduardo Marbán, M.D., of Cedars-Sinai Medical Center in Los Angeles, added high-dose antioxidants to cardiac stem cells being cultured in the typical laboratory culture of 20 percent oxygen in an effort to reduce oxidative stress, which was blamed for causing genetic abnormalities in 9 percent of cells generated. The researchers tested four culture environments: one with 20 percent oxygen, one with 5 percent oxygen (a physiological level), one to which a high dose of a commercial proprietary antioxidant was added, and one to which a high dose of a "homemade antioxidant cocktail" was added.

The researchers found that intracellular reactive oxygen species (ROS) levels were moderately reduced in the 5 percent oxygen environment, but they unexpectedly observed aneuploidy in the stem cells treated with the high doses of antioxidants. The researchers determined that while antioxidants suppress DNA damage at low concentrations, very high doses appear to increase damage. They stressed that antioxidant foods pose no danger but warned that excessive supplementation can.

"These results indicate that physiological levels of intracellular ROS are required to activate the DNA repair pathway for maintaining genomic stability in stem cells. The concept of an 'oxidative optimum' for genomic stability has broad implications for stem cell biology and carcinogenesis," the authors write.

One study author is a founder and holds equity in Capricor Inc., which develops stem cell products.

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Specialties Urology
Hematology & Oncology
Family Practice
Internal Medicine

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