University McGill UniversityThe popular dietary supplement ubiquinone, also known as Coenzyme Q10, is widely believed to function as an antioxidant, protecting cells against damage from free radicals. But a new study in Nature Communications finds that ubiquinone is not a crucial antioxidant—and that consuming it is unlikely to provide any benefit. Cells need it to produce energy from nutrients and oxygen—a function performed by tiny structures, known as mitochondria, within cells. Because of ubiquinone’s role in energy production, loss of the substance in the mice led to severe sickness and early death. At the same time, the research yielded new insights into the importance of ubiquinone in helping mitochondria produce energy.