Mushrooms against Alzheimer's disease
Alzheimer's disease (AD) stands as a prevailing neurodegenerative condition (NDs), leading to the gradual deterioration of brain cells and subsequent declines in memory, thinking, behavior, and emotion.
Despite the intensive research efforts and advances, an effective curative treatment for the disease has not yet been found.
Mushrooms, esteemed globally for their exquisite flavors and abundant nutritional benefits, also hold a wealth of health-promoting compounds that contribute to improving AD health.
These compounds encompass polysaccharides, proteins, lipids, terpenoids, phenols, and various other bioactive substances.
Particularly noteworthy are the potent neuroprotective small molecules found in mushrooms, such as ergothioneine, erinacine, flavonoids, alkaloids, ergosterol, and melanin, which warrant dedicated scrutiny for their therapeutic potential in combating AD.
In a new review (Foods 2023, 12(15), 2972) summarizes such positive effects of mushroom bioactive compounds on AD, with a hope to contribute to the development of functional foods as an early dietary intervention for this neurodegenerative disease.
Recent in vitro and in vivo studies have identified anticancer, antioxidant, antimicrobial, and neuro-protective properties in mushroom biomolecules, implying that mushroom consumption shows potential in delaying or even preventing cognitive impairment (CI) associated with AD.
Cohort studies on Japanese and Singaporean individuals above 65 have elucidated that frequent mushroom consumption significantly decreases dementia risk. The Singaporean cohort study revealed that as little as 300 g of mushrooms per week (two or three mushrooms) was sufficient to reduce mild cognitive impairment (MCI) risk by 50%.
Studies on Hericium erinaceus (lion's mane mushroom) have shown that its extracts and biomolecules effectively reversed cognitive and behavioral deficits in both preclinical animal trials and, remarkably, in clinical human trials.
Polysaccharide extracts from Coprinus comatus (shaggy mane mushroom) and Coprinellus truncorum were rich in β-glucans which exerted AChE inhibitory activity without the typical side effects associated with synthesis medicines.
Similar in vitro studies on murine models using polysaccharide extracts from Grifola frondosa (Maitake mushrooms), Pleurotus eryngii (king trumpet mushroom), and H. erinaceus all described neuroprotective and antioxidant properties in aging rats. The rats showed significantly improved cognition implying a reversal of neurodegeneration.
Inflammation, supported by glial cell activity, is one of the best-studied factors associated with AD and dementia. Mushrooms have a surprisingly high protein content, much higher than most food crops and vegetables. These proteins are comprised of novel peptides, some of which have been shown to possess potent anti-inflammatory properties.
While the lipid content of mushrooms is relatively low (0.1 – 16.3%), the oleic and linolenic acids that mushrooms contain have been shown to have similar anti-inflammatory effects as their peptides. Alpha linoleic acid was observed to protect murine neurons from Aβ-induced glial-cell-mediated neuroinflammation effectively. Mice in the test cohort (consuming the alpha-linoleic acid) showed significantly reduced neuronal cell loss compared to controls in an Aβ-infused mouse model.
Melatonin, ergosterol, terpenoids, and phenolic compounds extracted from mushrooms have been found to exhibit a whole spectrum of anti-AD benefits, ranging from neuro-protective to anti-inflammatory properties, especially in terms of neurons in the brain. Evidence points to brain inflammation as the primary cause of neurodegenerative disorders, including AD.
Consumption of these mushrooms or their extracts might pave the way for future therapies and interventions which replace conventional synthetic compounds with naturally derived, cheap, and nutritious alternatives, aiding in the campaign against AD and other age-related cognitive conditions.