Four 2023 papers that outlined or used different ergothioneine doses, starting with a human/rodent study:

“We found that cognitive function and hippocampal neurogenesis were lower in mice fed an ERGO-free diet than in those fed the control diet. Mice fed an ERGO-free diet were orally administered ERGO (0, 2, and 20 mg/kg) for two weeks which reversed these effects.

Phosphorylated brain-derived neurotrophic factor receptor TrkB, the activated form of TrkB, was also detected in extracellular vesicles (EVs) derived from serum samples of 52 volunteers who had been orally administered ERGO-containing tablets (5 mg/day for 12 weeks). The ratio of serum EV-derived phosphorylated TrkB was significantly higher in the ERGO-treated group than in the placebo-treated group and was positively correlated with both serum ERGO concentrations and several cognitive domain scores from Cognitrax.

The ratio of p-TrkB to TrkB in serum EVs was proposed as a quantitative diagnostic marker of long-term ERGO-induced cognitive improvement.”

https://www.researchsquare.com/article/rs-2626422/v1 “TrkB phosphorylation in serum extracellular vesicles correlates with cognitive function enhanced by ergothioneine in humans”

Human equivalents of all rodent ergothioneine doses were higher than the 5 mg/day for 12 weeks 2020 human study, cited as Reference 21. I couldn’t access that paper, so here’s its Abstract:

Effect of ergothioneine on the cognitive function improvement in healthy volunteers and mild cognitive impairment subjects – a randomized, double-blind, parallel-group comparison study

“These results indicate that continuous intake of ergothioneine improves cognitive function in healthy subjects.”

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A rodent study compared effects of a fermented product with 0.1 and 1.0 mg/g (human equivalent 6 mg (1 mg x .081) x  70 kg) ergothioneine doses:

“Our present study demonstrated for the first time the preventive effect of Rice-koji fermented extracts made by Aspergillus oryzae on anxiety, impaired recognition, and nociception using a psychophysically stressed model. Our results also demonstrated preventive effects of ergothioneine (EGT) on stress-induced anxiety- and pain-like behaviors.

Daily administration of High dose Rice-koji or 0.1 mg/kg EGT decreased anxiety- and pain-like behaviors. These findings suggest that inhibitory effects of Rice-koji on psychological stress might be mediated through the actions of EGT.”

https://www.mdpi.com/2072-6643/15/18/3989 “Preventive Roles of Rice-koji Extracts and Ergothioneine on Anxiety- and Pain-like Responses under Psychophysical Stress Conditions in Male Mice”

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Here’s one of several reviews that cited a 2017 clinical trial (duplicately Reference 39 and 61 for some reason) of 5 and 25 mg ergothioneine doses:

“In this pharmacokinetic study, forty-five healthy humans received placebo, 5, or 25 mg encapsulated ergothioneine/d for 7 d and were followed up for an additional 4 weeks. Ergothioneine was rapidly absorbed and largely retained by the body, with large increases in plasma ergothioneine levels and only minimal increases (<4 %) in urinary excretion observed. While plasma levels of ergothioneine decreased when supplementation was withdrawn, levels in whole blood continued to increase in a dose–response fashion, reaching maximal levels 3 weeks after withdrawal of supplement, which were sustained at 4 weeks follow-up.

A large difference in basal concentrations of ergothioneine in whole blood was observed. Participants with the highest basal levels of ergothioneine also appeared to take up more of supplemented ergothioneine.”

https://www.cambridge.org/core/journals/british-journal-of-nutrition/article/ergothioneine-an-underrecognised-dietary-micronutrient-required-for-healthy-ageing/92CED7FF201A9FB23BEAFF0D3EAD7316 “Ergothioneine: an underrecognised dietary micronutrient required for healthy ageing?”

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Wrapping up with a deep dive into seven mushroom varieties’ compounds:

“Mushrooms contain multiple essential nutrients and health-promoting bioactive compounds, including amino acid L-ergothioneine. We compared metabolomes of fresh raw white button, crimini, portabella, lion’s mane, maitake, oyster, and shiitake mushrooms using untargeted liquid chromatography mass spectrometry (LC/MS)-based metabolomics.

Results indicate significantly higher concentrations of L-ergothioneine in lion’s mane and oyster mushrooms compared to the remaining five mushroom varieties, which had concentrations ranging from 1.94 ± 0.55 to 5.26 ± 1.23 mg/100 g wet weight (mean ± SD). There was also variability in concentration of L-ergothioneine between mushroom varieties of the same farm. Different numbers denote significance (p < 0.05).

Mushrooms and their bioactive extracts are considered functional foods. Mushrooms have several bioactive compounds, including polysaccharides, lectins, terpenoids, sterols, and alkaloids, among others, which may positively impact health.

Cell walls of mushrooms contain polysaccharides, including β-glucans and chitin, which positively affect health, through modulating the immune system and protecting the cardiovascular system through improvements in glucose and lipid metabolism. Effects on the cardiovascular system are also attributable to lovastatin and polyphenols, known for their lipid-lowering and antioxidant properties, respectively.

While the 1344 compounds in common among the seven mushroom varieties support some level of similarity, detection of hundreds of unique-to-mushroom-variety compounds and differences in amino acid profiles indicate that not all mushrooms are chemically comparable. Given detection of >400 unique-to-mushroom-variety compounds in lion’s mane, maitake, oyster, and shiitake mushrooms, we suggest further targeted investigations on compounds detected and potential health benefits.”

https://www.mdpi.com/2304-8158/12/16/2985 “Metabolomics Profiling of White Button, Crimini, Portabella, Lion’s Mane, Maitake, Oyster, and Shiitake Mushrooms Using Untargeted Metabolomics and Targeted Amino Acid Analysis”

I eat around 200 grams of mushrooms daily, having temporarily overridden the boredom of eating AGE-less chicken vegetable soup every day. I prep all the top package’s frozen umami bomb (283 grams) and half of the bottom’s fresh mushrooms (340 grams) into the soup:

It makes servings for three days, including one for prep day dinner. I’d guess from “concentrations ranging from 1.94 ± 0.55 to 5.26 ± 1.23 mg/100 g (mean ± SD)” that my daily mushroom ergothioneine dose is around 7 mg ((1.94 mg + 5.26 mg) / 2) = 3.6 mg per 100 grams x 2 (for 200 grams).

Continued in Part 2.