Ergothioneine is a naturally occurring amino acid derivative with potent antioxidant properties, found in mushrooms and some other dietary sources. Its use to support mitochondrial health is primarily based on emerging scientific evidence rather than traditional medicine. Several preclinical studies have demonstrated that ergothioneine accumulates in mitochondria and protects cells from oxidative stress, a process particularly relevant for mitochondrial health because the mitochondria are both a major source and target of reactive oxygen species (ROS).

Research in cell culture and animal models suggests ergothioneine may preserve mitochondrial function by reducing oxidative damage, improving mitochondrial membrane potential, and enhancing the activity of mitochondrial enzymes. Some studies have shown that ergothioneine supplementation can reduce biomarkers of mitochondrial dysfunction in models of neurodegenerative disease or metabolic stress. However, human trials are limited and have not definitively confirmed these benefits in clinical settings.

The evidence base is still developing; while ergothioneine's biological plausibility and preclinical data are promising, clinical validation is lacking. Therefore, its rating is moderate (3/5) for supporting the mitochondria, reflecting substantial laboratory support but insufficient direct evidence in humans.