Cancer patients are turning to mega-doses of vitamin and mineral supplements, despite the fact that some research suggests high doses of antioxidants (including vitamins C and E, beta-carotene and selenium) can interfere with radiation and some types of chemotherapy, the New York Times reports. These cancer treatments attack tumor cells by creating free radicals—but vitamin supplements can “clean up” such free radicals, meaning they don’t attack the cancer. Other studies, meanwhile, suggest that just as healthy cells thrive around high doses of antioxidants, cancer cells do too. In the July issue of the medical journal Cancer, Columbia University researchers tracked vitamin use among 764 women. Among the 663 receiving chemotherapy, hormone treatment or radiation for breast cancer, 60.5 per cent said they were taking antioxidants during treatment; 70 per cent of those said they were taking high doses (higher than what’s in a popular multivitamin). The American Cancer Society suggests avoiding vitamin and supplement use during cancer treatment.