Ergothioneine From Mushrooms May Shield the Brain Against Parkinson's Disease

Parkinson's disease (PD) affects nearly 8 million people worldwide and remains incurable, with existing treatments offering only symptomatic relief. This urgency has intensified interest in neuroprotective nutraceuticals—natural compounds that might slow or prevent neurodegeneration. This review, authored by researchers from Nanyang Technological University and the National University of Singapore, makes a detailed case for ergothioneine (ET) as a uniquely promising candidate.

ET is a naturally occurring thiol/thione derivative of histidine, produced biosynthetically only by fungi and select bacteria. Dietary intake is dominated by mushrooms—especially lion's mane, oyster, cordyceps, and shimeji varieties—though trace amounts appear in garlic, asparagus, tempeh, and dairy. ET is taken up by the body via OCTN1 (encoded by SLC22A4), a transporter expressed broadly across human tissues, with particularly high expression in the midbrain (a region central to PD pathology) and in astrocytes—at levels seven-fold higher than neurons. This dedicated transporter system drives avid intestinal absorption, active renal reabsorption, and accumulation in tissues including the brain, giving ET a half-life of approximately one month—far exceeding most nutraceuticals, which clear within hours to days.

Human bioavailability data are compelling: daily supplementation of 25 mg ET for 7–28 days raised whole-blood ET by 125,000 nM, with less than 4% excreted in urine. In subjects with mild cognitive impairment (MCI), one year of ET supplementation produced an ~8-fold rise in plasma ET. Animal data corroborate this: ET-supplemented Drosophila showed 10–40-fold increases in brain/body ET, and mice showed a ~3-fold brain increase by day 28.

Epidemiological evidence links ET depletion to neurological risk. PD patients show ~45% lower serum ET than age-matched controls. In cognitively healthy individuals, lower baseline ET predicts accelerated decline across memory, attention, language, and executive function. Multi-omics analysis of the Alzheimer's Disease Neuroimaging Initiative cohort found that low ET in MCI patients was associated with a 12% higher rate of AD progression over two years. Low ET also correlates with cardiovascular disease, macular degeneration, and frailty, suggesting systemic physiological relevance.

Mechanistically, ET appears to act through multiple complementary pathways in pre-clinical PD models spanning C. elegans, Drosophila, rodent models, and human neuronal cultures. These include: reduction of alpha-synuclein aggregation (a hallmark PD pathology), restoration of mitochondrial membrane potential and complex I activity, attenuation of reactive oxygen species and oxidative DNA damage, suppression of apoptotic signaling, and dampening of neuroinflammatory cytokine cascades. This multifactorial profile distinguishes ET from single-target antioxidants. Early-phase clinical trials have established ET's safety profile and hinted at cognitive benefits, particularly in elderly populations with MCI. The authors call for larger, longer, placebo-controlled trials specifically in PD populations to establish efficacy and optimal dosing.