Coffee reduces prostate cancer risk

By Dr. Ananya Mandal, MDMay 17 2011

According to latest research, drinking more cups of coffee could more than halve the odds of developing a deadly prostate tumors.

In the 20-year study of almost 50,000 men, researchers noted that those who drank at least six cups a day were 20 per cent less likely to get prostate cancer than those who never took coffee. Strikingly, they were 60 per cent less likely than the non-coffee drinkers to die of the disease. The researchers also say that decaffeinated coffee is just as effective.

The research is significant because prostate cancer, the most common cancer among British men, affects 37,000 a year and kills more than 10,000. However, the Harvard University researchers say that non-coffee drinkers shouldn’t change their habits based on this study alone.

For this study the American team compared the coffee intake of men quizzed about their diets every four years between 1986 and 2006 with their medical records. Two-thirds of those taking part drank at least one cup of coffee a day and 5 per cent got through at least six, the Journal of the National Cancer Institute reports. Some 5,035 of the 47,911 men developed prostate cancer, with 642 of the tumors classed as potentially fatal.

Even relatively small amounts of coffee – one to three cups per day – lowered the risk of lethal prostate cancer by 30 per cent. And bigger amounts had a bigger effect. The researchers carefully adjusted for other factors so that the link cannot be explained away by the coffee drinkers having healthier lifestyles. In fact, they were more likely to smoke and did less exercise.

Caffeine is credited with a host of health benefits, including cutting the odds of asthma, Alzheimer’s and multiple sclerosis. But in this case, the researchers believe that other plant chemicals in coffee are behind the benefits. They think compounds such as anti-oxidants may cut the odds of prostate cancer and reduce the likelihood of deadly tumors by altering levels of sex hormones, regulating blood sugar levels and cutting inflammation. “An association between coffee and lower risk of advanced prostate cancer is biologically plausible,” they reported.

Kathryn Wilson, the study’s lead author, said, “If our findings are validated, coffee could represent one modifiable factor that may lower the risk of developing the most harmful form of prostate cancer.” But British experts said other studies had failed to find that coffee protected against prostate cancer.

Dr Helen Rippon, head of research management at the Prostate Cancer Charity, added, “It is important to remember that studying diet is difficult because you are not studying a standardized product – coffee can be prepared in many different ways from many different varieties of bean. That is why it is so important that studies like this are repeated by others, to see if the result stands up in other groups of men. Although this study is a welcome addition to our knowledge, it is far from definitive and we would not recommend men who are not already habitual coffee drinkers to become so in the hope of preventing prostate cancer.”  She warned that heavy caffeine intake is associated with other health problems.

The findings were the same in both caffeinated and decaffeinated coffee drinkers, said Lorelei Mucci, associate professor of epidemiology at the Harvard School of Public Health and co-author of the study. ”We're not sure exactly what helps the association,” said Mucci. “Coffee is one of the strongest antioxidants.” Coffee also helps with insulin and glucose metabolism, and may help regulate sex hormone levels, which all play a role in prostate cancer, she also explained.

Just one week ago, a Swedish study showed women who drink five or more cups of coffee a day had a much lower risk of developing an aggressive form of breast cancer. “Coffee now has been associated with a lower risk of diabetes, a lower risk of Parkinson's disease, a lower risk of cirrhosis and liver disease,” said Mucci.

But many experts, including Mucci, admit they're not willing to say that coffee is healthy. “This study is in isolation,” said Howard Soule, chief science officer at the Prostate Cancer Foundation. “Their finding does not impinge on pancreatic cancer, or other health effects that coffee may or may not be related to.” “All the epidemiological studies on risks and benefits of coffee look promising,” said Soule. “But then we're seeing the findings didn't hold up in prospective studies…The disclaimer is that it requires a prospective randomized trial over 20 years, which likely will never be done,” he said.