Coffee drinkers can be reassured about the health risks of enjoying their cup of java, doctors say.

In a study of more than 402,000 men and women aged 50 to 71 in the U.S., researchers looked at the association between coffee consumption and mortality.

Compared with men who did not drink coffee, those who drank six or more cups a day had a 10 per cent lower risk of death, Neal Freedman of the nutritional epidemiology branch at the U.S. National Institutes of Health and his co-authors reported in Wednesday's issue of the New England Journal of Medicine.

"Our results provide reassurance with respect to the concern that coffee drinking might adversely affect health," the researchers concluded.

Participants who had cancer or cardiovascular disease when the study began were excluded from the analysis.

Coffee contains more than 1,000 compounds besides caffeine that might be important to health. (Adeel Halim/Reuters)

The 13-year long observational study could not conclude if the inverse relationship between between coffee consumption and mortality reflects cause and effect, the authors said.

The beverage contains more than 1,000 compounds besides caffeine that might be important to health.

"There continues to be no good evidence that coffee drinking is harmful in really any way," said Dr. Martin Myers, a cardiologist at Sunnybrook Health Sciences Centre in Toronto.

Myers' research concluded caffeine doesn't increase blood pressure or cause heart rhythm problems.

Coffee and cancer

In previous studies, heart attacks were actually related to smoking rather than coffee. The latest paper also showed significant interactions between smoking and coffee consumption for risk of death from cancer.

There was an association between coffee consumption and deaths from cancer in men.

"It is not clear to us why there was a modest positive association in men but not women in our study," Freedman said in an email. "Differences in men and women for this outcome could reflect chance, as previous studies have generally not found an association."

Regular consumption of coffee might be helpful for Type 2 diabetes and perhaps cardiovascular disease and it doesn't do anything for cancer, said Frank Hu, a professor of nutrition and epidemiology at Harvard University in Boston, who reported similar mortality findings in 2008.

Coffee drinkers also tended to smoke, drink more than three alcoholic drinks a day, eat more red meat and showed less healthy behaviours like engaging in vigorous physical activity compared with those who did not drink coffee.

Consumption increases

The researchers asked whether coffee drinkers had caffeinated beverages more than half the time but they did not collect data on how the coffee was prepared.

At a coffee shop in Toronto, patrons were pleased to hear the news.

"I just worry about drinking too much caffeine and being sort of addicted to it," said Jack Mesquita, who normally drinks three or four espressos a day and sometimes has a cappuccino or coffee.

"It is going to encourage me isn't it?" he said with a laugh.

Another customer, Christopher Gonzalez, doesn't have more than two cups a day and says lately he's been trying to stick to one, mostly in the morning to help wake up.

"Coffee itself in my opinion is not bad for you at all," Gonzalez said. "But sugar is and I can not take my coffee without sugar or sweetener so that's the only reason I limit it."

Coffee consumption increased to 90 litres per person in 2009, an increase of 14 litres per person compared to 1989, according to Statistics Canada.

The research was funded by the U.S. National Institutes of Health and the U.S. National Cancer Institute's division of cancer epidemiology and genetics.

With files from CBC's Pauline Dakin and Melanie Glanz