It has been evaluated that older adults who consume at least 300 grams a week of mushrooms have reduced the risk of cognitive decline by 50%.
According to the team of researchers from the Department of Physological Medicine and the Department of Biochemistry at the Yong Loo Lin School of Medicine at the National University of Singapore, older adults who eat more than two standard servings (about 150 grams each) of mushrooms a week reduce your risk of mild cognitive impairment (MCI) by up to 50%.
"This correlation surprises and encourages," says Associate Professor Lei Feng, principal investigator on this work. "It appears that an accessible ingredient has a dramatic effect in slowing down cognitive decline." The study was carried out between 2011 and 2017 with more than 600 Chinese patients over 60 years of age. The results have been published in theJournal of Alzheimer's Disease.
ICM is defined as the intermediate step between natural age-related decline and the more severe deterioration leading to senile dementia. It manifests itself in the form of memory loss or difficulty in forming memories, as well as deficits in linguistic, visuospatial and attention span skills. They can be subtle symptoms, much less serious than those linked, for example, to Alzheimer's.
“People with ICM go on with their ordinary lives. What we had to determine was whether these older people had worse results on neuropsychological tests than people of the same age and background, ”Leng explains. "These tests are specifically designed to measure different aspects of a person's cognitive ability." Some are adaptations, he says, of the most widely used IQ test, the Wechsler Intelligence Scale for Adults.
Part of the test includes in-depth interviews with the study subjects, in which demographic information, medical history, psychological factors and dietary habits are collected. Likewise, measurements of blood pressure, weight, height, grip strength and walking speed were taken. Finally, they went through a test to measure levels of cognition, depression and anxiety. At the end of all this, the neuropsychological test took place which lasted two hours and yielded a score of dementia.
The mushrooms mentioned by the participants were of the variety of habitual consumption, both dried and packed, as well as some culinary specialties: shiitake mushrooms, oyster mushrooms or golden mushroom. The researchers note that almost all varieties contain a compound, ergothioneine, which may be behind their benefits for the brain.
"It is a unique antioxidant and anti-inflammatory that humans cannot synthesize on their own, but can be obtained through the diet and of which mushrooms are the main source," explains Dr. Irwin Cheah, chief biochemist. A previous study had already verified that ergothionein was found at lower levels in patients diagnosed with ICM, and the deficiency of this amino acid was linked to a neurodegenerative risk factor.
Other compounds of this food may be advantageous when it comes to preserving mental abilities, they indicate: hericenones and erinacines, for example, can stimulate the synthesis of factors for nerve regeneration. And the mushroom's bioactive components can protect the brain from neurodegeneration by inhibiting the production of harmful substances, such as beta-amyloid.
The next step for Feng's team is to test a synthesis of ergothioneine and other plant-based ingredients, such ascatechins of the green tea leaf, as a treatment against cognitive deterioration to evaluate the therapeutic potential of these phytonutrients. Additionally, interviews with healthy seniors can shed new insights into additional beneficial nutritional habits.