Selenosugars in Animals and Humans: Operational Nomenclature, Analysis, Occurrence, and Metabolic Pathways

Selenosugars are now recognized as the major end metabolites of selenium in mammals and play a central role in selenium detoxification and excretion. Since their discovery in the early 2000s, numerous studies have reported the occurrence of selenosugars in urine, tissues, and biological fluids of humans and animals. However, progress in the field has been hindered by inconsistent nomenclature, analytical limitations, and incomplete understanding of their metabolic origin and biological significance. In this position paper, we provide a comprehensive overview of the chemistry, occurrence, analysis, and metabolism of mammalian selenosugars. We propose a harmonized operational nomenclature that preserves essential structural information while facilitating communication among researchers. We critically evaluate analytical approaches used for selenosugar detection and quantification, including HPLC-ICP-MS, HPLC-ESI-MS, and NMR spectroscopy, and discuss their strengths, limitations, and appropriate applications. Based on accumulated evidence, we recommend minimum analytical criteria for reliable selenosugar identification and reporting. We further review the occurrence of naturally occurring selenosugars in humans and animals and integrate current knowledge into an updated metabolic framework. Adoption of the proposed nomenclature and analytical guidelines should improve consistency across studies and provide a foundation for future investigations into selenium metabolism and homeostasis.