Lots of people drink coffee. In the United States, 75 percent of adults do. Globally, more than 2 billion cups of coffee are consumed each day. Because so many people drink coffee, any health benefits conferred by a warm cup of joe are of substantial importance to public health.
Moderate coffee consumption can be part of a healthy diet. Research suggests that adults can consume up to 400 mg of caffeine a day (about four cups) without health consequences, such as heart disease, reproductive issues, and developmental issues. (A freshly brewed cup of coffee has about 12 mg of caffeine per ounce.) Moreover, coffee consumption is linked to lower risks for metabolic syndrome, diabetes, and cardiovascular disease.
The bigger question, however, is whether drinking coffee can actually cause health benefits. Does drinking coffee protect against disease and help you live longer? We don’t know for sure. However, two large (i.e., high-power) population studies published in the July 11 issue of Annals of Internal Medicine link coffee intake to lower risk of death across various races and ethnicities.
Large studies linking coffee to lower risk of death are an important step in eventually fleshing out whether coffee is really good for you, and whether drinking coffee is something a physician would recommend as a preventive health measure.
In the first large population study, Gunter and colleagues followed 451,743 participants representing 10 European countries for an average of 16 years. After controlling for several variables, including body mass index, physical activity, and smoking, the researchers found “that higher levels of coffee drinking are associated with lower risk for death from various causes, specifically digestive and circulatory diseases.”
This effect was observed among participants who drank three or more cups of coffee per day (the highest quartile) as compared with those who drank no coffee. Furthermore, coffee drinkers had better liver function and more favorable inflammatory biomarker profiles than those who didn’t drink coffee.
Of note, researchers observed these effects with both caffeinated and decaffeinated coffee drinkers, suggesting that biological compounds found in coffee other than caffeine—such as phenolic compounds, which, like caffeine, have antioxidant and antimutagenic properties—could be responsible for the observed effects.
The second coffee study from the Annals of Internal Medicine also indicated that coffee consumption was linked to a lower risk of death.
In this similar study, Park and co-authors followed 185,855 participants representing Latino, African American, Native Hawaiian, white, and Japanese American populations for an average of 16 years. Except for the Native Hawaiian population, decreased mortality was observed among all those who drank moderate amounts of coffee (between one and four cups a day). Of note, Park and colleagues controlled for smoking and other confounders.
We must remember to take these findings with a grain of salt and realize that these studies have their limitations. For instance, the data used for these studies were collected from questionnaires, and the self-reporting of coffee consumption can be inaccurate. Second, it’s nearly impossible to account for every, unforeseen confounding variable, such as the amount of sugar or cream added during preparation both of which increase calories.
Taken together, the results of these recent large population-based, prospective studies lend credence to the notion that coffee intake is linked to lower risk of death. These studies also suggest that the effects of coffee could extend to many races and ethnicities.
Guallar, E, et al. Moderate Coffee Intake Can Be Part of a Healthy Diet. Annals of Internal Medicine. July 11, 2017 (e-pub ahead of print).
Gunter, MJ, et al. Coffee Drinking and Mortality in 10 European Countries: A Multinational Cohort Study. Annals of Internal Medicine. July 11, 2017 (e-pub ahead of print).
Park, SY, et al. Association of Coffee Consumption With Total and Cause-Specific Mortality Among Nonwhite Populations. Annals of Internal Medicine. July 11, 2017 (e-pub ahead of print).