The Effect of Ergothioneine Supplementation on Cognitive Function, Memory, and Sleep in Older Adults with Subjective Memory Complaints: A Randomized Placebo-Controlled Trial

Ergothioneine is a diet-derived antioxidant with emerging evidence of neuroprotective benefits, but no dose-ranging study has evaluated its effects in healthy older adults. In this 16-week randomized, double-blind, placebo-controlled trial, 147 adults aged 55–79 with subjective memory complaints received ergothioneine (10 mg or 25 mg/day ErgoActive^®) or placebo. The primary outcome was the change in composite memory (CNS Vital Signs). Secondary outcomes included other cognitive domains, subjective memory and sleep quality, and blood biomarkers. At baseline, participants showed slightly above-average cognitive function (neurocognitive index median = 105), with plasma ergothioneine levels of median = 1154 nM (interquartile range = 889.9). Plasma ergothioneine increased by ~3- and ~6-fold for 10 mg, and ~6- and ~16-fold for 25 mg, at weeks 4 and 16, respectively (p < 0.001). 25 mg ergothioneine showed a within-group improvement in composite memory at week 4 (p < 0.05), although this was not sustained. Reaction time improved in both groups, dependent on time. Other domains showed null or limited effects. Subjective prospective memory and sleep initiation improved dose-dependently, with significant effects at 25 mg (p < 0.05). Liver function improved and a within-group increase in telomere length was noted. In conclusion, ergothioneine supplementation was safe and well tolerated, with evidence suggesting some benefits in this cohort of healthy older adults. Longer trials in individuals with lower baseline ergothioneine or cognitive function are warranted.