Two large studies published Monday in the Annals of Internal Medicine found that drinking at least one cup of coffee per day was associated with a reduced risk of early death from common diseases such as cancer, diabetes, and heart disease.
The findings support previous research that has found drinking coffee is not harmful to a person's health, but the authors warn the findings do not demonstrate a cause-and-effect between coffee consumption and longevity.
About the studies
One of the studies, conducted by researchers from the World Health Organization's (WHO) International Agency for Research on Cancer and Imperial College London, used data from the European Prospective Investigation into Cancer and Nutrition study, which tracked participants in 10 European countries (Denmark, France, Germany, Greece, Italy, the Netherlands, Norway, Spain, Sweden, and the United Kingdom) for about 16 years. The researcher's' data set included about 521,000 people.
July 26 WebconferenceHow to give your team the feedback they need to improve
For the other study, researchers from the University of Southern California (USC) examined coffee consumption among 185,855 U.S. residents who participated in the Multiethnic Cohort Study, which has tracked participants across various races and ethnicities for an average of 16 years. The researchers used that data to compare participants' coffee drinking habits with the 10 leading causes of death in the United States.
Both studies came up with similar results: Not only is coffee not bad for your health, it might actually be good for you.
In the WHO study, the researchers found in each of the 10 countries examined, individuals who were in the top 25 percent of coffee drinkers had a lower risk of death from compared with non-coffee drinkers. Even after accounting for smoking, diets, and other factors, the researchers found that the risk of early death in men and women was 12 percent and 7 percent lower, respectively, among coffee drinkers.
While the researchers observed a reduced likelihood of death from any cause among coffee drinkers, they found an even greater reduction in death from diseases related to the digestive and circulatory systems. The researchers also found that suicides were lower in men who regularly drank coffee—although not in women.
The researchers found that in a subset of 14,000 people, coffee drinkers generally had healthier livers and had better glucose control than the non-coffee drinkers. The researchers did find, however, that women with large coffee habits had an increased risk of death from ovarian cancer.
The effects of coffee
In the USC study, the researchers found that people who drank one to six cups of coffee per week had a decreased chance of early death, and this held true across nearly all racial and ethnic groups. The researchers did not observe any statistically significant declines in risk of early death among Native Hawaiians, but they said that was likely because they made up too small a portion of study participants.
They also found that people who drank one cup of coffee per day saw their chances of an early death from diseases such as cancer, chronic lower respiratory disease, heart disease, kidney disease, and stroke drop by 12 percent, while those who drank three cups of coffee per day saw their chances of an early death drop by 18 percent. However, the researchers said they observed no association between coffee and lower risk of death from Alzheimer's disease, accidents, influenza or pneumonia, or suicide.
Both studies reported similar results for individuals who drank decaffeinated coffee.
While the studies were not designed to show that consuming coffee directly reduced the risk of early death, the researchers say there are reasons to believe the compounds in coffee could be beneficial. For instance, Veronica Setiawan, associate professor of preventive medicine at USC and a senior author of the university's study, said, "Coffee contains a lot of antioxidants and phenolic compounds that play an important role in cancer prevention."
She added that, given the limitations of the study, "we cannot say coffee will prolong your life," but "we can say moderate coffee consumption can be incorporated into diet for a healthy lifestyle. For most, it seems, it likely won't cause harm."
Neil Murphy, a lead author of the WHO study, said, "Our results suggest that moderate coffee drinking, up to about three cups a day, is not harmful to your health, and that incorporating coffee into your diet could have health benefits."
However, in an accompanying editorial, Eliseo Guallar, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health who was not involved in the study, said it is "premature" to recommend coffee intake as a way "to reduce mortality or prevent chronic disease" (Blau, STAT News, 7/10; Oide, Sacramento Bee, 7/10; Kaplan, "Science Now," Los Angeles Times, 7/10; Seaman, Reuters, 7/10).
We can help you be more productive at work
Webinar: Become an inbox ninja in 30 minutes