Japan—Mushroom consumption may reduce the risk of development of prostate cancer among middle-aged and elderly Japanese men, according to a study published in theInternational Journal of Cancer.

36,499 men, aged 40-79 years, who participated in the Miyagi Cohort Study in 1990 and the Ohsaki Cohort Study in 1994 were followed for a median of 13.2 years. 3.3% of participants developed prostate cancer.

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Compared with mushroom consumption of less than once per week, consumption once or twice a week was associated with an 8% lower risk of prostate cancer. Consumption three or more times per week was associated with a 17% lower risk.

The study’s weak point: “Since information on mushroom species was not collected, it is difficult to know which specific mushrooms contributed to our findings,” said Shu Zhang, Ph.D., of the Tohoku University School of Public Health, in a press release. “Also, the mechanism of the beneficial effects of mushrooms on prostate cancer remains uncertain.”