Paper
Abstract A novel selenium form, nano red elemental selenium (Nano‐Se) was prepared by adding bovine serum albumin to the redox system of selenite and glutathione. Nano‐Se has a 7‐fold lower acute toxicity than sodium selenite in mice (LD 50 113 and 15 mg Se/kg body weight respectively). In Se‐deficient rat, both Nano‐Se and selenite can increase tissue selenium and GPx activity. The biological activities of Nano‐Se and selenite were compared in terms of cell proliferation, enzyme induction and protection against free racial‐mediated damage in human hepatoma HepG2 cells. Nano‐Se and selenite are similarly cell growth inhibited and stimulated synthesis of glutathione peroxidase (GPx), phospholipid hydroperoxide glutathione peroxidase (PHGPx) and thioredoxin reductase (TR). When HepG2 cells were co‐treated with selenium and glutathione, Nano‐Se showed less pro‐oxidative effects than selenite, as measured by cell growth. These results demonstrate that Nano‐Se has a similar bioavailability in the rat and antioxidant effects on cells.