Researchers from Japan believed they were the first to investigate this link, and that their work is “the first cohort study indicating the prostate cancer-preventive potential of mushrooms at a population level.”
They published their findings on the International Journal of Cancer.
Recruitment
In this study, 36,499 cancer-free men aged 40 to 79 years were followed for a median period of 13 years. Participants were part of two ongoing cohort studies: Miyagi and Ohsaki (total: 51,760).
The study excluded participants who were diagnosed before follow up, those who died, as well as those with missing values of mushroom consumption.
A food frequency questionnaire was used to collect data on mushroom consumption as well as other food and beverage items (categorised as <1, 1 to 2, ≥3 times/week).
Mushroom intake
During the follow up, 1,204 cases (1,204) of prostate cancer were identified.
It was reported that compared to participants with mushroom consumption below one time a week, frequent mushroom intake (one or more times a week) was associated with a significant lower risk of prostate cancer (p=0.023).
The mechanism of the beneficial effects of mushrooms on prostate cancer remained uncertain, but researchers have provided some possible answers.
They said, L-ergothioneine, an antioxidant present in large amounts in shiitake mushrooms, oyster mushrooms, maitake mushrooms and king oyster mushrooms, might mitigate oxidative stress/damage.
In a Phase 1 clinical trial, white button mushrooms also appeared to have anti-prostate cancer activity through immune modulation, although the active compounds are still unclear.
The researchers said: “We assume these bioactive components might play a role in the observed inverse relationship between mushroom consumption and incident prostate cancer, because shiitake, oyster mushrooms, maitake and white button mushrooms are commonly consumed in the study areas.”
Significant in older participants
The inverse relationship was especially obvious among participants aged over 50 years and did not differ by clinical stage of cancer and intake of vegetables, fruit, meat and dairy products.
This meant that a higher mushroom consumption was related to a lower risk of incident prostate cancer, especially among participants who had a lower consumption of vegetables and fruits as well as those who had a higher consumption of meat and dairy products.
However, no significant relationship between mushroom consumption and incident prostate cancer was observed among men aged under 50 years.
Limitations
The researchers admitted to several limitations in the study. First, mushroom consumption was only assessed once at baseline, so mushroom intake might have changed during follow up.
Secondly, since information on mushroom species was not collected, it was difficult to know which specific mushroom(s) contributed to the findings.
The researchers concluded that their study is the first present prospective cohort study with long-term follow-up, which observed an inverse relationship between mushroom consumption and incident prostate cancer, and suggested that habitual mushroom intake might help to prevent prostate cancer.
They recommended further studies in other populations and settings are required to confirm this relationship.
Source: International Journal of Cancer
https://doi.org/10.1002/ijc.32591
“Mushroom consumption and incident risk of prostate cancer in Japan: A pooled analysis of the Miyagi Cohort Study and the Ohsaki Cohort Study”
Authors: Shu Zhang, et al.