The Relationship of Coffee Drinking and Death

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The summary below is from the full report titled "The Relationship of Coffee Consumption with Mortality." It is in the 17 June 2008 issue of Annals of Internal Medicine (volume 148, pages 904-914). The authors are E. Lopez-Garcia, R.M. van Dam, T.Y. Li, F. Rodriguez-Artalejo, and F.B. Hu.

What is the problem and what is known about it so far?

Previous studies have found both favorable and unfavorable relationships between coffee drinking and death. However, recent studies link coffee drinking to less risk for type 2 diabetes, heart disease, and some types of cancer, which supports the hypothesis of a beneficial effect of coffee.

Why did the researchers do this particular study?

To examine the relationships between coffee drinking and risks for dying of heart disease, cancer, or any cause.

Who was studied?

41,736 men who had participated in the Health Professionals Follow-up Study and 84,214 women who had participated in the Nurses' Health 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.

How was the study done?

The men and women in the Health Professionals Follow-up Study and the Nurses' Health Study completed questionnaires every 2 to 4 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.

What did the researchers find?

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 (1980 to 2004 for women and 1986 to 2004 for men). This was mainly because of a 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.

What were the limitations of the study?

The design of the study does not permit the researchers to be certain that coffee decreases the chances of dying sooner than expected. There might be something else about coffee drinkers that protects them.

What are the implications of the study?

The study shows that drinking large amounts of coffee does not increase a person's risk for dying sooner than expected and may actually be protective.