Mushrooms are divisive, as far as foods go. Some people love their earthy flavour that seems to absorb the best parts of the food it’s served with. Others complain about their bland, rubbery texture. Most people don’t even realise that mushrooms aren’t vegetables. As fungi, they’re actually more closely related to animals than to plants from an evolutionary standpoint. They are a unique, strange food, and scientists from the National University of Singapore (NUS) may have uncovered an unexpected benefit of eating mushrooms: they may improve memory.
A team from the Department of Psychological Medicine and Department of Biochemistry at the Yong Loo Lin School of Medicine at NUS has found that seniors who consume more than two standard portions of mushrooms weekly may have 50 per cent reduced odds of having mild cognitive impairment (MCI).
MCI is the middle-phase of cognitive impairment that happens to most people as they grow older; it lies somewhere between normal function and more serious issues like dementia and Alzheimer’s. Seniors 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 visuospatial abilities. A key distinction between MCI and dementia is that the issues do not drastically affect the ability to function. However, they can still be very stressful and difficult, as anybody who’s ever lost a set of keys can confirm.
The six-year study, which was conducted from 2011 to 2017, collected data from more than 600 Chinese seniors over the age of 60 living in Singapore. The study involved extensive interviews and tests comparing groups who did or did eat more than two portions of mushrooms per week, with one portion defined as 150 g.
“People with MCI are still able to carry out their normal daily activities. So, what we had to determine in this study is whether these seniors had poorer performance on standard neuropsychologist tests than other people of the same age and education background,” explained Assistant Professor Lei Feng from the NUS Department of Psychological Medicine. “Neuropsychological tests are specifically designed tasks that can measure various aspects of a person’s cognitive abilities. In fact, some of the tests we used in this study are adopted from commonly used IQ test battery, the Wechsler Adult Intelligence Scale (WAIS).”
The researchers believe the reason for the reduced prevalence of MCI in mushroom eaters may be down to a specific compound found in almost all varieties of mushroom. Their findings found that people who ate more mushrooms performed better on tests and showed an overall lower level of MCI. Golden, oyster, shiitake and white button mushrooms, as well as dried and canned mushrooms were evaluated in this study. However, it is likely that other mushrooms around the world would also have beneficial effects.
“We’re very interested in a compound called ergothioneine (ET),” 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.”
The researchers believe that other compounds found in mushroom may be beneficial as well. The next steps for the researchers is to isolate ET and other plant-based compounds to observe their efficacy in delaying cognitive decline. This will allow researchers to locate the source of the benefits more precisely. Assistant Professor Feng and his team also hope to identify other dietary factors that could be associated with healthy brain ageing and reduce risk of age-related conditions in the future.
This post was written by Miles Martin and edited by Karolina Zieba.