A new study was published in The Journal of Alzheimer's Disease showing a reduced risk of mild cognitive impairment (MCI) in people who ate mushrooms more often, as compared to those who ate mushrooms less or not at all. The study has a strong statistical power with a large cohort of 633 subjects and contributes to other high quality studies showing similar results.
The researcher's note in their introduction, "We hypothesized that mushroom consumption is associated with reduced odds of having MCI, and this association is independent of potential confounders such as age, gender, education level, lifestyle factors, and certain medical condition that are associated with cognitive impairment" (Feng et al., 2019, p. 2).
This research aimed to add additional data to similar studies that showed similar results. The researchers found that "The reduction [of risk] was significant for participants who consumed greater than 2 portions of mushrooms per week. Our findings are consistent with earlier studies that have examined the relations between mushroom consumption and cognitive health in aging among community-living elderly. Using data from the Hordaland study, Nurk and colleagues found that mushroom consumers had better performance on all six cognitive tests as compared with non-consumers; the dose-response association of mushrooms on cognitive performance tended to be linear" (Feng et al., 2019, p. 5).
"The reduction [of risk] was significant for participants who consumed greater than 2 portions of mushrooms per week. Our findings are consistent with earlier studies that have examined the relations between mushroom consumption and cognitive health in aging among community-living elderly."
The Hordaland study referenced in the new study was performed in Norway and published in the British Journal of Nutrition in 2010. The study did not specifically study the effects of mushroom consumption on cognitive health alone, but included all fruits and vegetables, which they note have been shown to reduce risk for cardiovascular disease, and cancer.
The researchers introduced their study noting the protective cognitive effects of phytochemicals in fruits and vegetables, especially antioxidants, "... it is acknowledged that fruits and vegetables are rich in antioxidants and bioactive compounds that may reduce disease risk stemming from reactive oxygen species and are also associated with cognitive benefits" (Nurk et al., 2010, p. 1190). Their very complex and detailed study revealed interesting results, notably, "Total vegetable consumption had the strongest associations with executive function, perceptual speed, global cognition and semantic memory" (p. 1198). They also noted a fairly consistently linear relationship between cognitive benefits and fruits and mushroom consumption. In their conclusion, they summarize mushroom consumption on cognitive performance, noting the results are supported in a placebo-controlled trial:
"Although only about one-quarter of the present study population reported consumption of mushrooms, we found that this was strongly positively associated with perceptual speed, executive function and semantic memory (m-DST and S-task) and there were also better test scores related to episodic memory and executive function (KOLT and TMT-A) among mushroom eaters as compared with non-eaters. Recently, in a double-blind placebo-controlled trial, intake of tablets containing 96 % of mushrooms (Hericium erinaceus) was effective in improving mild cognitive impairment reversibly." (p. 1198)
Mushroom Consumption Details: "What should I aim for?"
In the Singapore study, they specified the types of mushrooms:
"The questionnaire included six mushrooms that are commonly consumed in Singapore: 1) mushroom, golden; 2) mushroom, oyster; 3) mushroom, shiitake; 4) mushroom, white button; 5) mushroom, dried; 6) mushroom, button, canned, drained. For each item, the participants were asked to report the frequency of consumption at portion unit. A portion was defined as a standard serving, that is one three-quarter cup of cooked mushrooms with an average weight of around 150 g." (p. 2)
So based on these results, it would encourage us to eat a minimum of two portions of your preferred or a variety of mushrooms, per week, to reduce risks for cognitive decline and/or improve cognitive performance. We should note that when the researchers speak of 'risk' they generally refer to relative risk, which means small incremental effects on overall absolute risk of a disease occurring.
To clarify about the difference between relative and absolute risk:
"Absolute risk is the actual risk of some event happening given the current exposure. For example, if 1 in 10 individuals with exposure develops the disease then the absolute risk of developing the disease with exposure is 10% or 1:10. If only 1 in 100 individuals without exposure develop the disease, then the absolute risk for developing the disease without exposure would be 1% or 1:100. Thus the relative risk of developing the disease would be 0.1 / 0.01 = 10. Therefore, an individual has a 10% chance of developing the disease with exposure (absolute risk), 1% chance of developing the disease without exposure (absolute risk), and they are 10 times more likely to develop the disease if they have exposure (relative risk)." (Tenny & Hoffman., n.d.)
They summarize: "Our cross-sectional data support the potential role of mushrooms and their bioactive compounds in delaying neurodegeneration."
So basically: drink tea, and eat fruits, vegetables, and mushrooms in abundance along with other healthy, organic, and fresh sources of fats and proteins to protect yourself from chronic and debilitating diseases.
Feng, L., Cheah, I. K. M., Ng, M. M. X., Li, J., Chan, S. M., Lim, S. L., ... & Halliwell, B. (2019). The Association between Mushroom Consumption and Mild Cognitive Impairment: A Community-Based Cross-Sectional Study in Singapore. Journal of Alzheimer's Disease, (Preprint), 1-7.
Nurk, E., Refsum, H., Drevon, C. A., Tell, G. S., Nygaard, H. A., Engedal, K., & Smith, A. D. (2010). Cognitive performance among the elderly in relation to the intake of plant foods. The Hordaland Health Study. British journal of nutrition, 104(8), 1190-1201.
Tenny S, Hoffman MR. Relative Risk. [Updated 2019 Jan 19]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK430824/
Note: Nothing in this post is intended to diagnose or treat disease or illness. Consume mushrooms with discretion and avoid wild-picked or non-commercial mushrooms without expert guidance. Seek professional medical guidance to address your questions and medical concerns.