Mushrooms are much more than just a culinary delight; they are gaining significant scientific attention for their potential health benefits, especially when it comes to brain function. Often called "functional mushrooms," these fungi contain unique compounds like polysaccharides, terpenoids, polyphenols, and peptides, which contribute to their ability to support our immune system, act as antioxidants, reduce inflammation, and even fight microbes. The market for these beneficial mushrooms is booming, with sales in North America expected to grow by 15% annually from 2024 to 2030.

Let's explore some of these fascinating fungi and their potential impact on cognitive health.

Lion's Mane: The Brain's Best Friend?

Lion's Mane (scientific name: Hericium erinaceus), also known as Yamabushitake, is easily recognizable by its unique, long, white spines that resemble a lion's mane. This mushroom primarily grows on hardwood trees in temperate forests across North America, Europe, and Asia. For centuries, it has been valued in Asia for both its taste and its medicinal properties.

Modern research is particularly interested in Lion's Mane for its potential to support brain health. Studies suggest it can help promote the growth of new brain cells (neurogenesis), improve memory and concentration, and even offer protection against diseases that affect the brain.

What makes Lion's Mane so special? It's packed with bioactive compounds, including polysaccharides, terpenoids, and phenolic compounds.

• Polysaccharides, especially beta-glucans, are known for their ability to support the immune system and protect brain cells.
• Terpenoids, specifically hericenones and erinacines, are particularly exciting. They have been shown to stimulate the production of Nerve Growth Factor (NGF). NGF is a vital protein for the growth, maintenance, and survival of neurons (brain cells), making it highly relevant for conditions like Alzheimer's (AD) and Parkinson's disease (PD). Erinacines are particularly notable as they can cross the blood-brain barrier and exert strong protective effects on neurons. For example, Erinacine A has been shown to increase NGF levels in the brain, encouraging the growth of new neurons and the survival of existing ones. Hericenones, on the other hand, have shown potential in improving cognitive function and memory.
• Phenolic compounds in Lion's Mane act as powerful antioxidants, helping to reduce oxidative stress and inflammation in the brain.

Lion's Mane also contains ergothioneine, another beneficial compound. Compared to other medicinal mushrooms, Lion's Mane is particularly recognized for its neuroprotective properties. It also offers gut benefits, as its prebiotic polysaccharides feed beneficial gut bacteria, promoting a healthy gut environment.

Human Studies on Lion's Mane:

• Mild Cognitive Impairment: A study involving Japanese adults aged 50-80 with mild cognitive impairment showed significant improvement in cognitive function after taking 1000 mg of Lion's Mane three times a day for 16 weeks, compared to a placebo group. However, these improvements decreased after stopping supplementation.
• Cognitive Function, Stress, and Mood in Young Adults: A study on healthy adults aged 18-45 found that a single dose of 1.8g of Hericium erinaceus led to quicker performance on a cognitive task. After 28 days of supplementation, there was a trend towards reduced subjective stress.
• Cognitive Function in Healthy Adults over 50: In a 12-week study, participants over 50 taking 3.2 grams of Lion's Mane extract daily showed significant improvements in cognitive functions, particularly in a mini-mental status exam, and it helped prevent short-term memory deterioration.
• Early Alzheimer's Disease: A double-blind study on patients with mild AD found that those taking an erinacine A-enriched Lion's Mane extract showed significant improvements in cognitive assessments and daily living activities compared to a placebo group. A review of both human and animal studies further suggests that Hericium erinaceus, especially the erinacine-A-enriched form, could be a promising candidate for future therapeutic treatment and delayed progression of Alzheimer's disease.

Reishi: The "Mushroom of Immortality"

Ganoderma lucidum, commonly known as Reishi or Lingzhi in Asian countries, has been used in traditional Chinese medicine for thousands of years. It's often called the "mushroom of immortality" ²⁴ due to its long history of use for immune-enhancing and anti-aging properties. Reishi is also known for its antioxidant properties and its ability to protect the liver, and it's used as an adaptogen, helping the body adapt to stress.

Reishi contains a vast array of beneficial compounds, including over 432 secondary metabolites and more than 200 different types of polysaccharides. Among these are over 380 terpenoids and more than 30 steroidal groups.

Reishi and Alzheimer's Disease:

• Research indicates that Reishi's active components can help inhibit the aggregation of amyloid (a protein linked to AD), prevent the formation of tangles in brain cells, and suppress inflammatory pathways.
• Reishi also has activity that counters one of the primary mechanisms of neuronal damage in AD, potentially alleviating pathological changes.
• Studies have evaluated Reishi's safety, confirming its low toxicity.
• In one study, patients with mild AD who received Reishi spore powder combined with memantine (a common AD medication) showed improved behavioral and cognitive abilities and a significantly better quality of life compared to those receiving memantine alone.
• Another study found that an oral Reishi polysaccharide extract was well-tolerated and led to significant reductions in severity and fatigue scores in patients with AD.
• Overall, research suggests that G. lucidum can positively impact cognitive function, symptoms, and quality of life in AD patients, possibly due to its anti-amyloidogenic, antioxidant, anti-inflammatory, neuroprotective, and immune-modulating properties.

Ergothioneine: The Longevity Vitamin

Ergothioneine (ET) is a unique sulfur-containing compound that our bodies cannot produce; we must get it from our diet. Mushrooms are the leading source of ET, with oyster mushrooms having particularly high levels. Other sources include chicken liver and kidney, grains, beans, garlic, and broccoli.

Scientists have observed a connection between ET levels and cognitive health:

• A decline in ET levels has been linked to increasing severity of cognitive impairment in humans.
• Low plasma ET levels have been shown to predict accelerated cognitive decline in individuals who are otherwise cognitively normal, suggesting that low ET may precede cognitive problems.
• ET may protect against mitochondrial dysfunction, counteract inflammation, and act as an antioxidant.
• Low ET levels may predispose individuals to neurodegeneration.
• Importantly, ET can cross the blood-brain barrier and is highly distributed in the brain. It also has anti-aging properties and helps regulate aging-related signaling pathways.

Human Studies on Ergothioneine:

• Mild Cognitive Decline: In a study of individuals aged 60 or older with mild cognitive impairment, those who received 25 mg of ergothioneine three times a week for one year showed improved learning ability and stabilized plasma levels of a neurofilament light chain (a marker of neuronal damage), compared to a placebo group who saw no improvement and an increase in the marker. The study also confirmed ET's safety, with no adverse effects on blood counts, kidney, or liver function.
• Cognitive Decline in the Elderly: A study examining 470 elderly subjects found that lower plasma ET levels were associated with poorer cognitive performance at the start of the study and faster rates of decline in overall function and various cognitive areas, including memory, executive function, attention, and language, over five years.
• Neurodegeneration and Cerebrovascular Disease: A cross-sectional study of nearly 500 participants found that plasma ET concentrations were lowest in individuals with dementia. Lower ET levels were also linked to white matter hyperintensities and brain atrophy (reduced global cortical thickness and hippocampal volumes), which are markers of brain damage. The decreasing ET levels along the continuum from no cognitive impairment to dementia suggest that low ET could be a biomarker for cognitive impairment and may contribute to neurodegeneration and cerebrovascular disease-associated cognitive impairments, possibly by worsening oxidative stress.

A Fungal Future for Brain Health?

The research on functional mushrooms like Lion's Mane, Reishi, and the compound ergothioneine is exciting. These natural compounds show significant promise in supporting cognitive function, protecting against neurodegenerative diseases, and promoting overall brain health. As we continue to learn more about these powerful fungi, they may play an increasingly important role in maintaining our mental sharpness and well-being.

‍