Antioxidants are well covered in advertising. They protect cells by neutralizing free radicals before these can cause cellular damage. While some antioxidants, such as certain vitamins, are obtained through the diet, the body can produce its own antioxidants. An international team from the Max Planck Institute and Tohoku University in Sendai has now shown for the first time that mammalian cells produce and store elemental sulfur in a controlled manner in the form of cyclooctasulfur (S₈). This molecule, which consists of eight sulfur atoms, serves as a precursor for an endogenous antioxidant.