Increased mushroom intake may reduce risk of prostate cancer, study finds

08 Oct 2019 --- Regular mushroom consumption may lead to a reduced risk of prostate cancer. This is according to a cohort study conducted by the Tohoku University, which analyzed more than 36,000 Japanese men’s mushroom intake to discover potential health benefits mushrooms provide. Published in the International Journal of Cancer, the study suggests that habitual mushroom intake might help to prevent prostate cancer. The effect was especially pronounced in men aged 50 or older and those with relatively low fruit and vegetable intake and high meat and dairy intake.

“Our study has suggested the promising health effect of mushrooms on humans,” Shu Zhang, an Assistant Professor of Epidemiology in the Department of Health Informatics and Public Health at Tohoku University School of Public Health and lead author of the study telIs NutritionInsight.

“In vivo and in vitro studies have shown that mushrooms have the potential to prevent prostate cancer. However, the relationship between mushroom consumption and incident prostate cancer in humans has never before been investigated. To the best of our knowledge, this is the first cohort study indicating the prostate cancer preventing potential of mushrooms at a population level,” Zhang notes.

The results
Within the median 13.2 years of conducting this cohort study, only 1.204 (3.3 percent) cases of prostate cancer were documented. The relationship between mushroom consumption and prostate cancer persisted among participants up to 50 years old. However, no significant relationship was observed among participants younger than 50. 

Although the difference was insignificant, the risk of incident prostate cancer remained lower for participants who consumed mushrooms more frequently than not. Participants who consumed mushrooms once or twice a week had an 8 percent lower risk of developing prostate cancer, compared to those who ate mushrooms less than once per week. Meanwhile, those who consumed mushrooms three or more times per week had a 17 percent lower risk than those who ate mushrooms less than once a week.

The study followed a total of 36,499 men, aged 40-79 in Miyagi and Ohsaki, Japan, from 1990 and 1994 respectively. The follow-up duration for the Miyagi cohort extended from June 1, 1990 to December 31, 2014 (24.5 years), while the follow-up duration for the Ohsaki cohort extended from January 1, 1995 to March 31, 2008 (13.25 years). 

The study suggests a promising health effect of mushrooms on humans.“The observational study of a specific food-disease association is often sensitive to other food consumption. Surprisingly, although the intake of vegetables, fruit, meat, and dairy products were considered, in our study, the inverse association between mushroom consumption and incident prostate cancer did not change substantially. Moreover, eating mushrooms three times (or more) per week has been shown to be enough to provide a statistically significant, 17 percent lower risk of prostate cancer,” Zhang notes. 

Research obstacles
Zhang notes that the most challenging part of the research was its observational nature. Therefore, it could not totally be free of bias and confounding factors. “To deal with these issues, we used a valid Food Frequency Questionnaire to collect the habitual mushroom consumption,” he explains. The participants submitted their personal information regarding lifestyle choices, including the intake of mushrooms and other food consumption, physical activity, smoking and drinking habits, as well as information on their education, and family and medical history.

“We also used the records of the Miyagi Prefectural Cancer Registry, one of the oldest and most accurate population-based cancer registries in Japan. With that information, we could obtain the incidence of prostate cancer and residential status, adjust a lot of potential confounding factors and did a series of sensitivity analyses,” she says.

Fungi health benefits
Mushrooms have a long history of being consumed as food and used in Asian medicine. To date, an increasing number of in vivo and in vitro studies have suggested the beneficial effects of mushrooms on health, such as antioxidation and anti-inflammation. Additionally, mushrooms also reportedly facilitate the alleviation of mild cognitive impairment (MCI) in seniors by up to 50 percent. 

“Mushrooms are a good source of vitamins, minerals and antioxidants, especially L-ergothioneine,” Zhang affirms. They are believed to mitigate against oxidative stress, a cellular imbalance resulting from poor diet and lifestyle choices and exposure to environmental toxins. Such toxins can lead to chronic inflammation and diseases, as well as cancer. Mushrooms also hold potential for prebiotic diabetes treatment, a US-based study found last year.  

“Based on these findings, further studies that provide more information on dietary intake of mushrooms in other populations and settings are required to confirm this relationship,” Zhang concludes. 

By Anni Schleicher