A cup of java may not be a bad idea for men's health: Drinking lots of coffee may reduce their risk of prostate cancer, researchers report.
The investigators analyzed data from 16 studies conducted around the world. Together, the studies involved more than a million men, about 58,000 of who went on to develop prostate cancer. The team was led by urologist Dr. Kefeng Wang, of China Medical University in Shenyang.
Their analysis couldn't prove cause-and-effect, but compared to men with the lowest coffee consumption, those who drank the most coffee had a 9% lower risk of prostate cancer.
As well, each additional daily cup of coffee was associated with a 1% reduction in risk, according to the research published online Jan. 11 in the journal BMJ Open.
Further analysis showed that compared to those with the lowest consumption, men who drank the most coffee had a 7% lower risk of localized prostate cancer, and a 12% to 16% lower risk of advanced and fatal prostate cancer, respectively.
The highest amounts of coffee consumption ranged from two to nine or more cups a day, while the lowest ranged from none to fewer than 2 cups a day.
"This study suggests that increased coffee consumption may be associated with a reduced risk of prostate cancer," Wang's group wrote. "Further research is still warranted to explore the underlying mechanisms and active compounds in coffee," they added, but "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 said their findings do need to be interpreted with caution because unmeasured or uncontrolled factors in the observational studies could have affected the overall prostate cancer risk estimate.
Still, there are plausible biological explanations for the connection. Wang's team noted that coffee improves blood sugar metabolism, has anti-inflammatory and antioxidant properties, and affects sex hormone levels, all of which may influence the development and progression of prostate cancer.
Two U.S. prostate cancer experts with no involvement in the study concurred that there could be real merit to the findings, although both offered up caveats.
While the findings appear "pretty convincing, there are lots of pitfalls with a meta-analysis [data from multiple studies] that can question the results," said Dr. Phillip Vigneri, chair of radiation medicine at Staten Island University Hospital in New York City. But he said there's other evidence of coffee's goodness against a range of health issues such as heart disease, kidney disease and liver troubles, as well as lowered risks for Alzheimer's disease and colon cancer.
Dr. Art Rastinehad, vice chair of urology at Lenox Hill Hospital in New York City, agreed. "I do believe there is an associated risk reduction in prostate cancer associated with coffee consumption," he said, but the data in a mea-analysis make it tough to make any recommendations as to how much coffee is enough (or too much).
And he stressed that the effects of high coffee intake aren't all benign, since "[excessive] coffee can lead to increased gastroesophageal reflux, anxiety and other medical problems."
Still, Vigneri believes that moderate coffee intake probably isn't a bad thing.
"Enjoy that cup of Joe," he said, but "like most dietary recommendations, too much is as bad as too little. A safe coffee intake is 3-5 cups a day, although those with a caffeine sensitivity may do better with less."