Coffee Drinking Not Unhealthy and is Possibly Associated with Lower Risk of Death

Division of Cancer Epidemiology And Genetics

Coffee is one of the most widely consumed beverages in the United States and worldwide, but the association between coffee consumption and the risk of death remains unclear, with previous studies yielding mixed results. A recent analysis by NCI researchers of data from the NIH-AARP Diet and Health Study, a large study of older adults, suggests that coffee drinking may be associated with a lower risk of death for most diseases and other causes. However, they did not find a lower risk of death by cancer among coffee drinkers.

The analysis*, by researchers from NCI’s Division of Cancer Epi­demiology and Genetics (DCEG), showed that people who report­ed that they drank coffee (whether caffeinated or decaffeinated), had a slightly lower risk of death from heart disease, respiratory disease, stroke, injuries and accidents, diabetes, and infections than those who did not report drinking coffee.

The NCI researchers observed these results among study participants after adjusting for the effects of other risk factors on mortality, such as smoking and alcohol consumption. The scientists cautioned, however, that they can’t be sure whether these associations mean that drinking coffee actually makes people live longer.

“A few recent studies have suggested that people [who drink coffee] have a slightly lower risk of death,” explained Neal Freedman, Ph.D., M.P.H., who led the new analysis within DCEG. “Because it was a very modest effect, we wanted to look at this in a really big population cohort like NIH-AARP study, [which enabled us] to look for even modest associations between coffee drinking and different causes of death.”

Dr. Freedman noted, “There has been a lot of concern that drinking coffee was not a healthy thing to do. Some people describe coffee drinking as their ‘guilty pleasure.’ Although we cannot infer a causal relationship between coffee drinking and lower risk of death, we believe these new results do provide some reassurance that coffee drinking does not adversely affect health.”

Dr. Freedman and his colleagues examined the association between coffee drinking and risk of death in 400,000 U.S. men and women ages 50 to 71, who participated in the NIH-AARP study. Researchers collected information about coffee intake once by questionnaire at study entry in 1995–1996, and followed the participants until their date of death or December 31, 2008, whichever came first. More than 52,000 participants died during the study period.

The researchers found that the association between coffee and reduction in risk of death increased with the amount of coffee consumed. Compared with men and women who did not drink coffee, those who consumed three or more cups of coffee per day had an approximately 10% lower risk of death. In addition, the DCEG scientists found that coffee drinking was not associated with increased cancer mortality among women, but did find a slight, and only marginally statistically significant, association of heavier coffee intake with increased risk of cancer death among men.

Dr. Freedman cautioned that in the NIH-AARP study the amount of coffee consumption was assessed by self-report at only a single time point and therefore might not reflect long-term patterns of actual coffee intake by the study participants. Also, information was not available to researchers on how the coffee was prepared (espresso, boiled, or filtered). The NCI scientists consider it likely that coffee preparation methods affect the levels of different components in the coffee consumed. Dr. Freedman said that DCEG researchers hope to examine these factors in future studies.

“The mechanism by which coffee protects against risk of death –if indeed the finding reflects a causal relationship – is not clear,because coffee contains an estimated 1,000 different compounds that might potentially affect health,” Dr. Freedman added.

Another recent analysis of data from the NIH-AARP study, led by Rashmi Sinha, Ph.D., also of NCI’s DCEG, indicated that people who drank four or more cups of coffee (caffeinated or decaffeinated) per day had a lower risk of colon cancer incidence**, particularly cancers of the region known as the proximal colon. DCEG researchers also recently reported an inverse association between coffee drinking and endometrial cancer*** but found no association between coffee consumption and breast cancer risk among the NIH-AARP study participants****.