“Further research is still warranted to explore the underlying mechanisms and active compounds in coffee,” they wrote.
Prostate cancer is the most common cancer and the second leading cause of cancer death in men in the United States, according to the American Cancer Society.
Past research has linked coffee consumption to a reduced risk for liver, bowel and breast cancers.
For this report, the Chinese researchers analyzed data from 16 studies, seven conducted in North America, seven in Europe and two in Japan.
Collectively, the studies included more than 1 million adult male participants, nearly 58,000 of whom developed prostate cancer.
Among the studies, 15 compared the risk for prostate cancer among those who consumed high amounts of coffee to those who drank less, while 13 reported on the risk associated with drinking additional daily cup, the researchers said.
The highest level of coffee consumption ranged from two to nine or more cups per day, while the lowest level ranged from none to fewer than two cups per day, they said.
A high level of coffee consumption reduced prostate cancer risk by 9% compared to low-level consumption, with each additional daily cup further lowering risk by 1%, the data showed.
The highest coffee intake was associated with a 7% lower risk for localized prostate cancer compared to the lowest level of consumption, and a 12% to 16% lower risk for advanced and fatal prostate cancer, the researchers said.
However, the design and methods of the included studies varied, so caution is warranted in interpreting the findings, the researchers said.
That said, plausible biological explanations exist for their findings, as coffee improves glucose metabolism, has anti-inflammatory and antioxidant effects and affects sex hormone levels, all of which may influence the development and progression of prostate cancer, they said.
“If the association is further proved to be a causal effect, men might be encouraged to increase their coffee consumption to potentially decrease the risk of prostate cancer,” the researchers wrote.