X-rays may not heal broken bones, but low doses of ionizing radiation may spark other health benefits, a new study of mice suggests. Radiation in high doses has well-known harmful effects. Scientists had thought low doses would do less extensive damage but could add up to big problems later. But radiation acts differently at low doses, producing health benefits for mice with an unusual genetic makeup, Randy Jirtle of the University of Wisconsin–Madison and colleagues report online November 1 in the FASEB Journal. Antioxidant vitamins, such as vitamins C and E, erased those health gains. “What goes on at high...