We all have our childhood heroes. One of my favourite heroes (apart from Scooby Doo) will be unknown to many of you. His name was Richard Evans Schultes and he was truly the last of his kind. He was essentially an ‘Indiana Jones’ type figure, one of the most important explorers of the 20th century who is regarded as the father of Ethnobotany. An ethnobotanist studies how indigenous peoples use plants for medical, rituals, and practical purposes. This man was described as one of the last great explorers in the Victorian tradition and he did in fact even wear a pith helmet! He was considered the preeminent authority on hallucinogenic and medicinal plants. He died in 2001 at the age of 86, he collected more than 24,000 species of plants in the Amazon basin, 120 of which bear his name, and he even has 2.2 million tract of protected rainforest in Columbia named after him. He famously said in 1992 ‘I do not believe in hostile Indians. All that is required to bring out their gentlemanliness is reciprocal gentlemanliness’. That statement tells us all we need to know! Many of our common medicines were first discovered from plants, then later synthesised to make them more available. The Amazon is of course of treasure trove, it has been estimated there are up to 80,000 different plant species, a truly staggering diversity.
Research continues to reveal interesting new avenues of investigation and we don’t necessarily have to be in the Amazon basin up to our knees in mud and surrounded by clouds of insects, as rich an environment as it might be. It isn’t only plants that confer medicinal benefits. As unlikely as it may seem the humble mushroom also contains diverse yet exclusive bioactive compounds that are not found in plants. Evidence is beginning to indicate that a dietary intake of mushroom or mushroom-based extracts might have beneficial effects on human health and even improve brain function. This was first suggested in the Journal of Medicinal Food (2017) in a study titled ‘Edible and Medicinal Mushrooms: Emerging Brain Food for the Mitigation of Neurodegenerative Diseases’. I recently wrote a short piece on dementia and current estimates suggest that there are about 850,000 cases in the UK, although with the current population age profile, this will rise to two million by 2051.The Medical Research Council website states “there is currently no cure for any of the neurodegenerative conditions that give rise to dementia, this represents one of the toughest medical and economic challenged our facing society today”.
It was thought that nerve regeneration in the mammalian central nervous system was not possible. However, it is becoming apparent that damaged neurons have to capacity to regenerate under the presence of stimulatory substances such as nerve growth factor (NGF) and brain derived neurotrophic factor (BDNF). Interestingly the article in the Journal of Medicinal Food we just mentioned suggested that “selected edible and medicinal mushrooms may effectively enhance neurite outgrowth in the brain by stimulating NGF production, mimicking the NGF reactivity, or by protecting neurons from neurotoxicants-induced cell death. Mushrooms may fulfil a preventive function against the development of Alzheimer’s disease.” The study concluding by suggesting that regular consumption of the mushrooms may possibly reduce or delay development of age-related neurodegeneration. Very interesting!
This pioneering research appears to be supported by further study, the results of which have just been published this month. This new exciting study from National University of Singapore (NUS) found that elderly participants who consumed more than two standard portions of mushrooms per week appeared to have a 50 per cent reduced odds of having what they called ‘mild cognitive impairment’ (or MCI). A portion was defined as roughly three quarters of a cup of cooked mushrooms. This six-year study, was conducted from 2011 to 2017, collected data from more than 600 Chinese seniors over the age of 60 living in Singapore. The results were published online in the Journal of Alzheimer’s Disease on 12th March 2019. The lead author of the work Professor Lei Feng said ‘The correlation is surprising and encouraging. It seems that a commonly available single ingredient could have a dramatic effect on cognitive decline.’
Mild cognitive impairment (MCI) is typically viewed as the stage between the cognitive decline of normal ageing and the more serious decline of dementia. MCI is essentially a condition in which someone has minor problems with cognition – their mental abilities such as memory or thinking. In MCI these difficulties are worse than would normally be expected for a healthy person of their age. However, the symptoms are not severe enough to interfere significantly with daily life, and so are not defined as dementia. It is estimated that between 5 and 20% of people aged over 65 have MCI. It is not specifically a type of dementia, but a person with MCI is more likely to go on to develop dementia. People afflicted with MCI often display some form of memory loss or forgetfulness and may also show deficit on other cognitive function such as language, attention and visual/spatial abilities. However, the changes can be subtle, as they do not experience disabling cognitive deficits that affect everyday life activities, which is characteristic of Alzheimer’s and other forms of dementia.
In the study at NUS six commonly consumed mushrooms were referenced. They were golden, oyster, shiitake and white button mushrooms, as well as dried and canned mushrooms. However, it is likely that other mushrooms not referenced would also have beneficial effects. The researchers suspected the reason for the reduced prevalence of MCI may be to do with a specific compound found in almost all varieties of mushrooms. “We’re very interested in a compound called ergothioneine ” said Dr Irwin Cheah, Senior Research Fellow at the NUS Department of Biochemistry. “ET is a unique antioxidant and anti-inflammatory which humans are unable to synthesise on their own. But it can be obtained from dietary sources, one of the main ones being mushrooms.”
Ergothioneine (or ET) is an unusual sulphur-containing amino acid discovered a century ago in the rye ergot. The only organisms known to synthesize it are a few bacteria and most mushrooms. We acquire ET solely through diet. We concentrate ET in cells and tissues frequently exposed to oxidative stress with highest levels being in blood, lens of the eye, liver, bone marrow and seminal fluid. What is very interesting is that an earlier study at the University of Singapore demonstrated that people with MCI had significantly lower plasma levels of ET than lower than age-matched healthy individuals. This deficiency in ET may be a risk factor for neurodegeneration and increasing ET intake through mushroom consumption might possibly promote cognitive health. The potential next stage of research for the team at NUS is to perform a randomised controlled trial with the pure compound of ET and other plant-based ingredients, such as L-theanine and catechins which both come from tea leaves, to determine the efficacy in delaying cognitive decline.
It is worth mentioning that there are other compounds contained within mushrooms that may also be advantageous for decreasing the risk of cognitive decline. Certain hericenones, erinacines, scabronines and dictyophorines may promote the synthesis of nerve growth factors. Bioactive compounds in mushrooms may also protect the brain from neurodegeneration by inhibiting production of beta amyloid sheets and tangles of tau (these plaques formations contribute to Alzheimer’s disease)
So, the moral of the story is perhaps the full English breakfast (obviously including mushrooms), whilst high in saturated fats, has one highly desirable component. H E Bates one of our most prolific writers, most famous for ‘Love for Lydia’ and the ‘Darling Buds of May’, was a great advocate of walking through the Northamptonshire country side and picking mushrooms. He once said, “The cookery books will give you a thousand finicky devices, mushrooms in this, mushrooms in that, but there is only one way—to fry them, simply with bacon, until they swim in their black fragrant juice.” He probably didn’t realise the full benefits that these wonderfully tasty mushrooms conferred!