Most Americans aren’t particularly drawn to mushroom — except as a pizza-topping.
That’s very different in East Asia, where mushrooms are much more commonly consumed.
Mushrooms are also favored foods in Russia and Eastern Europe, where forest fungi-foraging is a popular seasonal activity.
Certain mushrooms are also considered important medicines and medicinal foods in Russia, China, Japan, and East Asia generally.
The best-known medicinal mushroom species — which enjoy substantial scientific support — include Reishi (Lingzhi), Chaga, Cordyceps, Lion’s Mane, Turkey Tail, and Maitake (Hen of the Woods).
But recent research suggests that some of America’s most commonly consumed mushrooms — including white button, crimini, portobella, and (especially) porcini mushrooms — offer previously unsuspected health benefits.
Two years ago, we summarized encouraging findings about the uncommon antioxidants found in common commercial fungi: see Newly Discovered Magic in Mushrooms.
Now, new findings from Singapore add to prior indications that most mushrooms offer substantial brain-clarity benefits.
This study was designed to look for any links between elements of the participants’ diets and the presence of mild cognitive impairment (MCI) or “brain fog”.
Before we get to the remarkably encouraging results of the study, let’s take a closer look at MCI or brain fog.
Defining terms: What is MCI or brain fog?
Mild cognitive impairment (MCI) is the stage between the cognitive decline associated with normal aging and out right dementia, whose most common is Alzheimer’s disease.
People afflicted with MCI — usually those aged over 55 — typically display some memory loss and may also display declines in other cognitive functions, such as language, attention, and “visuo-spatial” abilities.
However, unlike the dramatic declines seen in Alzheimer’s and other forms of dementia, MCI is characterized by subtle changes. As the study’s lead author, Assistant Professor Lei Feng, said, “People with MCI are still able to carry out their normal daily activities.”
East Asian study links mushrooms to reduced risk for brain fog
The new findings come from a multi-disciplinary team at the National University of Singapore (NUS).
Their six-year study, which ran from 2011 to 2017, analyzed data gathered from 663 ethnically Chinese residents of Singapore aged 60 or above who’d volunteered for the Diet and Healthy Aging (DaHA) study (Feng L et al. 2019).
They compared the brain performances of two groups among the study’s volunteers:
A portion was defined as three quarters of a cup of cooked mushrooms with an average weight of about 5.3 ounces (150 grams). To put that amount in perspective, two 5.3-ounce portions would fill about half of a typical dinner plate.
As Dr. Feng said, “What we had to determine in this study is whether these seniors had poorer performance on standard neuropsychologist tests than other people of the same age and education background.”
The researchers interviewed the study volunteers, measured their basic physical characteristics and study nurses measured each participant’s blood pressure, weight, height, handgrip, and walking speed.
The team also gathered demographic information, medical histories, and information about the volunteers’ psychological factors and overall dietary habits.
Finally, each participant underwent two hours of standard tests proven to effectively measure cognition (thinking and memory) performance, depression, anxiety, and early signs of dementia.
Then, the results of these mental-performance tests were discussed in depth with expert psychiatrists to ensure an accurate diagnosis of each participant’s mental state.
The Singapore team compared the results of the mental tests in the two groups and calculated these apparent benefits:
Importantly, that calculation of the reduced mushroom-related risk for MCI accounted for the known impacts of overall diet, lifestyle, and physical characteristics on mental performance.
And the results of their analysis suggest that even one small portion of mushrooms a week may significantly reduce the risk for MCI.
Mushrooms and mental performance
The researchers believe the reason for the reduced prevalence of MCI among people who eat mushrooms frequently may be down to a specific antioxidant compound found in almost all varieties.
“We're very interested in a compound called ergothioneine (ET),” said Dr. Irwin Cheah, Senior Research Fellow at the NUS Department of Biochemistry. “ET is a unique antioxidant and anti-inflammatory [agent] which humans are unable to synthesize on their own.”
(ET featured prominently in the research we reported in Newly Discovered Magic in Mushrooms.)
An earlier study by the same team revealed that seniors diagnosed with MCI had significantly lower blood levels of ET, compared with than age-matched healthy people (Cheah IK et al. 2016).
The results of that study led the team to suspect that raising someone’s ET intake through increased mushroom consumption might promote cognitive health and reduce the risk for cognitive decline.
They also noted that other mushroom compounds may reduce the risk of cognitive decline. These include ones that — based on the results of studies in rodents — promote the growth of brain cells and connections between them (Phan CW et al. 2012; Phan CW et al. 2013; Ling-Sing Seow S et al. 2013).
And the Singapore group mentioned that other mushroom compounds may protect the brain from neurodegeneration in two ways (Phan CW et al. 2015):
• By inhibiting production of the beta amyloid and phosphorylated tau associated with Alzheimer’s.
• By inhibiting production of the acetylcholinesterase enzyme, which leading Alzheimer’s medications are designed to block.
Next steps in the Singaporeans’ search for anti-fog agents
The Singapore group would like to perform a randomized controlled clinical trial testing pure compound ET and other isolated plant compounds, such as L-theanine and catechins from tea leaves, to determine their efficacy for delaying cognitive decline.
Dr. Feng and his team also hope to identify other dietary factors that could promote healthy brain aging and reduce the risk of age-related conditions.
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• Feng L, Cheah IK, Ng MM, Li J, Chan SM, Lim SL, Mahendran R, Kua EH, Halliwell B. The Association between Mushroom Consumption and Mild Cognitive Impairment: A Community-Based Cross-Sectional Study in Singapore. J Alzheimers Dis. 2019 Feb 11. doi: 10.3233/JAD-180959. [Epub ahead of print]
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