Drinking coffee—whether it is regular or decaffeinated—can lower the risk of prostate cancer among men, according to researchers at the Harvard School of Public Health.

In a new study published on May 17, men who regularly drank six or more cups of coffee daily were nearly 20 percent less likely to develop any form of prostate cancer than those who had none. Furthermore, coffee drinkers had a 60 percent lower risk of lethal prostate cancer—the most severe form of the disease, which often spreads to the bones and results in death.

Researchers examined the coffee consumption of 47,911 men every four years from 1986 to 2008 as part of the Health Professionals Follow-Up Study. While consuming six or more cups daily reduced the risk of lethal prostate cancer by 60 percent, even drinking one to three cups can lower the risk by 30 percent.

“But people should not change their coffee habits based on any one study,” said lead author Kathryn M. Wilson, a research fellow in epidemiology at the School of Public Health.

Prostate cancer, the most frequently diagnosed form of cancer, is the second leading cause of death among U.S. men, affecting one in six men during their lifetimes.

Wilson said there has been evidence that physical activity and abstinence from smoking can also help reduce the risk of prostate cancer.

Coffee has different biological effects on insulin, antioxidant, and sex hormone levels that are helpful in determining men’s risk of prostate cancer, Wilson said.

“Coffee is so commonly consumed and it is of interest because of its large intake in our population,” Wilson said.

Prior studies have shown that coffee is also associated with a lower risk of type 2 diabetes, Parkinson’s disease, gallstone disease, and liver cancer.

The study, “Coffee Consumption and Prostate Cancer Risk and Progression in the Health Professionals Follow-up Study,” was published in an online edition of the Journal of the National Cancer Institute.

—Staff writer Jane Seo can be reached at janeseo@college.harvard.edu.