Concerns about the safety of ‘healthful‘ plant-based antioxidants’, including those renowned for their apparent ability to prevent cancer have been raised by scientists.

They are calling for more research on the possibility that some antioxidants may actually aggravate or even cause cancer in some individuals.

Their recommendation follows a study in which two such antioxidants – quercetin and ferulic acid – appeared to aggravate kidney cancer in severely diabetic laboratory rats.

Kuan-Chou Chen, Robert Peng, and colleagues note that vegetables, fruits, and other plant-based foods are rich in antioxidants that appear to fight cancer, diabetes, heart disease, and other disorders.

Among those antioxidants is quercetin, especially abundant in onions and black tea, and ferulic acid, found in corn, tomatoes, and rice bran.

Both also are ingredients in certain herbal remedies and dietary supplements. But questions remain about the safety and effectiveness of some antioxidants, with research suggesting that quercetin could contribute to the development of cancer, the scientists note.