Ergothioneine as an emerging food-derived bioactive compound protecting against age-related diseases: issues needing more research.

Ergothioneine (ET) is a chemically stable, tasteless, odorless, highly water-soluble diet-derived compound that is avidly absorbed and retained by the human body using a selective transporter, organic cation transporter novel 1 (often called the ET transporter). A substantial and growing body of evidence supports a role for ET in maintaining human health and protecting against age-related diseases, especially neurodegenerative diseases, and multiple studies indicate that low blood/plasma/serum ET concentrations increase risk of developing age-related diseases. Despite the growing interest in ET, much fundamental work remains to be done to investigate its metabolism, actions (if any) on the genome, lipidome, metabolome, and proteome, intracellular and intercellular transport (especially in the brain), precise mechanisms of cytoprotection, interactions with the microbiome, mycobiome, and human pathogens, and identifying the factors that control body ET levels. This narrative review explores these issues and suggests what research needs to be done to improve our understanding of ET biology.