Nootropic Fungi- Does the scientific evidence support the claims?

How do mushrooms Cordyceps, Lions Mare and Reshi affect the brain?

Fungi are a class of organisms that is neither plant nor animal. There has been huge recent hype surrounding mushrooms such as Shiitake, Chaga, Reishi, Lion’s Mane, Turkey tail and Cordyceps with claims for the medicinal benefits for everything from cancer to weight loss and the supplement industry in this area grows year on year. Yet with most of the current evidence low-grade, in small cohorts mainly in vitro (in a lab test tube or cell culture) or in animals and large-scale randomized-controlled-trials (the gold standard of scientific evidence), the evidence does not support many of the claims, especially in the largely unregulated (unlike pharmaceuticals) world of supplements. However new technology has enabled more evidence into these. So how do they help the brain and which ones have the most evidence behind them?

Lions Mane

There are many animal models on the effects of this mushroom on anxiety in mice which show that purified extracts of Hericerin compounds in Lions (63) Mane increase (64) nerve cells in culture and that powdered Lions Mane increases Nerve Growth Factor and Brain Derived Growth Factor (BDGF) in mice. There is huge possibility for this mushroom in future studies.

Nutritionally, mushrooms have many benefits. It is high in blood sugar stabilizing protein. In only 100 g serving of lions mane there is 35 calories, 7 g of carbohydrates and 22 g of protein per 100 g of dry mushrooms. It is also an incredible non animal source of essential amino acids. It contains high amounts of antioxidants, insulin sensitizing beta glucans, and other unique polysaccharides that help boost and support the immune system. Lion’s mane is rich in potassium and iron, vitamin D (as mushrooms are like humans and make vitamin D in their skin) and anti-inflammatory antioxidants, and so, brain cells aside, the mushroom has benefits for physical and mental health.

Shiitake

When mushrooms are powdered in supplements, we break down the food matrix which affects the bioavailability of the nutrient source. Thus, like all mushrooms shiitake mushrooms are best in whole food form and are rich in bioavailable protein and vitamin D. Again there is (65) low-grade evidence for mushrooms (either extracts from basidiocarps/mycelia or isolated compounds) reducing beta amyloid-induced neurotoxicity and had anti-acetylcholinesterase, neurite outgrowth stimulation, nerve growth factor (NGF) synthesis, neuroprotective, antioxidant, and anti-(neuro)inflammatory effects in mice, helping to reduce the symptoms of brain diseases and enhance brain health. Shiitake have long been a large part of Japanese and Chinese herbal medicine. Recent investigations have implicated adenosine in anxiety-triggering mechanisms, while eritadenine, an adenosine brain chemical copy from Shiitake mushroom, show huge potential (66). However, it is unclear whether these effects occur in humans at this stage (67, 68).

Chaga

Chaga is a mushroom which has been shown in (68) trials to support the brain-gut axis and gut health. Again it is rich in vitamin D, protein, iron and antioxidants. However, there is limited evidence that Chaga has any specific brain health benefits at this stage. Despite not being plants, and phytochemicals being the bio-active components of plants, there are polyphenols in mushrooms and these may account for some of the claims for reducing oxidative stress, neuroinflammation, and modulation of acetylcholinesterase activity, protecting neurons or stimulation, and regulating neurotrophins synthesis. However, again the evidence is not there currently.

Reishi

Evidence in animal models looks at mushrooms at different life cycle stages. This includes mycelium (the vegetative stage), sporocarps (the reproductive stage), or spores (the end product of the reproductive stage), and each stage provides a variety of bioactive compounds. These bioactive compounds include glycoproteins, polysaccharides, triterpenoids, meroterpenoids, sesquiterpenoids, steroids, alkaloids, benzopyran derivatives, and benzoic acid derivatives, amongst others which are said to be neuroprotective and protect the brain from disease. These compounds are said to have health benefits. However, it is unclear how exactly at the moment (69).

Cordyceps

This mushroom has been shown to help repair (70) spinal cord barrier (BSCB) disruption by inhibiting matrix metalloprotease activity, leading to improvement of functional outcomes after spinal cord injury. Therefore it is said to have huge potential for treating and improving brain function and injury outcomes. Again though, more research is needed in this area.

Overall?

There is huge potential for future clinical research into fungi, but the claims by supplements at the moment do not support the evidence. There is no harm in trying these as they may have benefit, if even just through their multiple nutritional benefits as they are high in many essential amino acids protein sources, rich in vitamin D for immunity, high fibre, B vitamin rich, iron rich, low carbohydrate and sugar and low fat. All types (even the humble chestnut mushroom) are amazing and should be an everyday part of a healthy diet.

References

1. Abitbol A, Mallard B, Tiralongo E, Tiralongo J. Mushroom Natural Products in Neurodegenerative Disease Drug Discovery. Cells. 2022;11(23).

2. Jayachandran M, Xiao J, Xu B. A Critical Review on Health Promoting Benefits of Edible Mushrooms through Gut Microbiota. Int J Mol Sci. 2017;18(9).

3. Shevchuk Y, Kuypers K, Janssens GE. Fungi as a source of bioactive molecules for the development of longevity medicines. Ageing Res Rev. 2023;87:101929.

4. Lee JY, Choi HY, Baik HH, Ju BG, Kim WK, Yune TY. Cordycepin-enriched WIB-801C from Cordyceps militaris improves functional recovery by attenuating blood-spinal cord barrier disruption after spinal cord injury. J Ethnopharmacol. 2017;203:90–100.