Kuan-Chou Chen of Taipei Medical University Shuan-Ho Hospital in Taiwan is calling for the U.S. Food and Drug Administration and other health agencies to re-evaluate the safety of plant-based antioxidants because rat studies have shown two actually made cancer worse in rats. Both also are used in some herbal remedies and dietary supplements.
The study, reported in the Journal of Agricultural and Food Chemistry, indicated two of these antioxidants found in plants -- quercetin and ferulic acid -- aggravated kidney cancer in severely diabetic laboratory rats.
"In this study we report that quercetin aggravated, at least, if not directly caused, kidney cancer in rats," Chen and colleagues say in a statement. "Some researchers believe that quercetin should not be used by healthy people for prevention until it can be shown that quercetin does not itself cause cancer."
The researchers say quercetin is especially abundant in onions and black tea and ferulic acid is found in corn, tomatoes, and rice bran.