Lion's mane (hericium erinaceus) is one of the edible mushrooms widely distributed in Japan and China. I've been seeing it for sale in grocery stores, so I decided to see if had any remarkable benefit.
Nerve growth factor (NGF) belongs to a family of proteins that play a part in maintenance, survival and regeneration of neurons during adult life. As we age, NGF declines, resulting in less efficient brain functioning. In mice, its absence leads to a condition resembling Alzheimer's disease. In 1986, two scientists won a Nobel Prize in Physiology / Medicine for the discovery and isolation of NGF. Since its discovery, researchers have been interested in ways of enhancing the uptake of NGF. Because NGF is unable to cross the blood brain barrier, it cannot be administered as an oral drug. Accordingly, scientists directed their attention to finding bio-active chemicals with a low molecular weight that could penetrate the BBB and could be taken orally to induce synthesis of NGF in the brain.
Enter lion's mane. A class of compounds called hericenones in lion's mane has been discovered to stimulate production of NGF, causing neurons to regrow:
Study: The Inducer of the Synthesis of Nerve Growth Factor From Lion's Mane (Hericium erinaceus)
Other compounds in lion's mane are also believed to be bio-active. A fat-soluable fraction isolated from lion's mane, called Amyloban, was found to protect against endoplasmic reticulum stress and/or oxidative stress dependent neuronal cell death caused by toxic beta amyloid peptide:
Patent Application: Anti-dementia substance from hericium erinaceum and method of extraction
Beta amyloid peptide is the main component of plaque that develops in the brains of Alzheimer's disease patients, causing destruction of neurons as it progresses. So far, Amyloban has been found to contain bio-active dilinoleoyl-phosphatidylethanolamine (DLPE) benzoate compounds:
Study: Dilinoleoyl-phosphatidylethanolamine from Hericium erinaceum protects against ER stress-dependent Neuro2a cell death via protein kinase C pathway.
Study: An endoplasmic reticulum (ER) stress-suppressive compound and its analogues from the mushroom Hericium erinaceum.
Study: Endoplasmic reticulum (ER) stress-suppressive compounds from scrap cultivation beds of the mushroom Hericium erinaceum.
The question remains, has it been tested in humans or animals? It turns out it has been tested. A study at a Chinese pharmaceutical university compared a lion's mane extract standardized to contain hericenones and Ambyloban with a common Alzheimer's drug. One hundred rats were injected with with beta amyloid peptide to create an Alzheimer's type dementia. The rats were then divided into groups to receive either lion's mane extract or the drug once a day for four weeks. At four weeks, an assessment of learning and memory related behavior was made for seven days.
Results showed that rats given the the extract performed a water maze test equally to or better than those given the Alzheimer's drug, depending on dosage. Sacrificing the rats after the examination, it was found the rats who received the lion's mane extract produced significantly more NGF.
Study (in Chinese): Anti-dementia effects of a low polarity fraction extracted from Hericium erinaceum
A clinical study using lion's mane was conducted to investigate its effectiveness against dementia in a rehabilitation hospital in Japan.
Study: Compounds for dementia from Hericium erinaceum
Results showed that after six months of taking lion's mane, six out of seven patients experienced improvements in their overall functional independence measure. In particular, three bedridden patients were able to get up to eat meal after administered.
Another study, this one a double blind, placebo controlled study, demonstrated that lion's mane is effective in patients diagnosed with mild cognitive impairment.
Study: Improving effects of the mushroom Yamabushitake (Hericium erinaceus) on mild cognitive impairment: A double-blind placebo controlled clinical trial.
It was observed that the lion's mane group's score increased with the duration of the intake, and four weeks after terminating the supplement, their scores decreased significantly. Laboratory tests showed no adverse effects of lion's mane.
These studies are very encouraging!