A new study published today in Annals of Internal Medicine has good news for coffee drinkers: Regular coffee drinking (up to 6 cups per day) is not associated with increased deaths in either men or women. In fact, both caffeinated and decaffeinated coffee consumption is associated with a somewhat smaller rate of death from heart disease.
Women consuming two to three cups of caffeinated coffee per day had a 25 percent lower risk of death from heart disease during the follow-up period (which lasted from 1980 to 2004 and involved 84,214 women) as compared with non-consumers, and an 18 percent lower risk of death caused by something other than cancer or heart disease as compared with non-consumers during follow-up. For men, this level of consumption was associated with neither a higher nor a lower risk of death during the follow-up period (which lasted from 1986 to 2004 and involved 41,736 men).
The editors of Annals of Internal Medicine caution that the design of the study does not make it certain that coffee decreases the chances of dying sooner than expected. Something else about coffee drinkers might be protecting them. And some measurement error in the assessment of coffee consumption is inevitable because estimated consumption came from self-reports.
"Coffee consumption has been linked to various beneficial and detrimental health effects, but data on its relation with death were lacking," says Esther Lopez-Garcia, PhD, the study's lead author. "Coffee consumption was not associated with a higher risk of mortality in middle-aged men and women. The possibility of a modest benefit of coffee consumption on heart disease, cancer, and other causes of death needs to be further investigated."
The researchers analyzed data of 84,214 women who had participated in the Nurses' Health Study and 41,736 men who had participated in the Health Professionals Follow-up Study. To be in the current study, participants had to have been free of cancer and heart disease at the start of those larger studies.
The study participants completed questionnaires every two to four years that included questions about how frequently they drank coffee, other diet habits, smoking, and health conditions. The researchers then compared the frequency of death from any cause, death due to heart disease, and death due to cancer among people with different coffee-drinking habits.
Among women, 2,368 deaths were due to heart disease, 5,011 were due to cancer, and 3,716 were due to another cause. Among men, 2,049 deaths were due to heart disease, 2,491 were due to cancer, and 2,348 were due to another cause.
While accounting for other risk factors, such as body size, smoking, diet, and specific diseases, the researchers found that people who drank more coffee were less likely to die during the follow-up period. This was mainly because of lower risk for heart disease deaths among coffee drinkers.
The researchers found no association between coffee drinking and cancer deaths. These relationships did not seem to be related to caffeine because people who drank decaffeinated coffee also had lower death rates than people who did not drink coffee.
The study, "The Relationship of Coffee Consumption with Mortality," was supported by National Institutes of Health research grants.