Does Lion’s Mane Mushroom Powder Have Benefits for Dementia?

I've talked about the benefits of nitrate-rich vegetables for improving cognitive function. Do any other vegetables stand out? Mushrooms aren't a class of their own, literally. In fact, a kingdom of their own, belonging to the fungi rather than the plant kingdom. Epidemiological studies in Japan, Singapore, Norway, the Netherlands, and the United States have found associations between mushroom consumption and superior cognitive function. Compared to people who don't eat mushrooms, those in the highest category of mushroom intake in the U.S. had a higher performance on various cognitive tests, and that highest intake was only averaging about one mushroom a day. This result appeared to be independent of other dietary and lifestyle factors. The researchers suggested it may be the unique mushroom antioxidant ergothioneine that I've profiled previously, and indeed a study out of France found blood ergothioneine levels associated with lower odds of cognitive decline. The U.S. research team suggested that regular mushroom consumption may reduce the risk of cognitive decline, but it was just a cross-sectional snapshot in time, so you don't know which came first. Japanese researchers performed a prospective study following more than 10,000 men and women aged 65 and older for about 6 years. In that time, about 1 in 12 was diagnosed with dementia. What seemed a lower risk of falling into that faction? Mushroom consumption. Compared to those who ate mushrooms less than once a week, those who ate mushrooms three or more times a week had a 19% lower chance of becoming demented. The cross-sectional study in Singapore found 57% lower odds of having cognitive impairment among those eating more than two portions a week. As always, though, cause and effect can only be established with interventional trials. A 6-month randomized, double-blind, placebo-controlled trial randomizing older men and women to plain white button mushrooms or placebo found no difference in cognitive function, but the dose was only about 200 mg a day of dried mushroom powder. That's the fresh weight equivalent of less than a quarter of a single small mushroom a day. This enabled the researchers to stuff the mushrooms into capsules so they could be blinded against placebo, but offers little insight to what even a single daily serving of mushrooms might do, which would constitute 50 times the study dose. What about fancier fungi, like the gourmet edible mushroom called lion's mane, or less palatably, bearded tooth fungus? In 2009, a pilot study found that older men and women diagnosed with mild cognitive impairment randomized to a few grams of dried lion's mushroom powder a day experienced a significant improvement in cognitive function compared to placebo starting as soon as month two. Despite the promising results, an attempt to replicate the results wasn't published for another decade. Researchers tried about 3 grams of powdered lion's mane mushroom a day in cognitive healthy older adults. A significant improvement over placebo was found in one of three cognitive measures. Finally, in 2020, a study was published on lion's mane mushroom for early Alzheimer's disease, a nearly year-long randomized double-blind placebo-controlled trial of about a gram a day of dried and powdered lab-grown lion's mane. Sadly, it found no cognitive benefits compared to placebo, but it did perhaps improve the ability to perform activities of daily living, a measure of independence.