Drinking coffee may reduce all-cause mortality

We've been writing about the positive health effects of coffee, both caffeinated and decaffeinated, for over a decade, yet there continues to be that perception that coffee is bad for you, whether because of a short-term increase in heart rate (only associated with caffeinated coffee) or because of a connection with an increase in LDL cholesterol (the "bad" cholesterol).

Yet the vast majority of research into the effects of coffee consumption is positive, and today's article is no exception.

Authors in Spain continued with their analysis of the SUN (Seguimiento Universidad de Navarra - University of Navarra Follow-Up) Project, a study of university graduates in Spain that began in 1999 and continues today (Am J Clin Nutr 2018;5(1):1113-1120). Participants respond to demographic, lifestyle, health, and dietary questionnaires at baseline and are re-surveyed regarding their health every two years after joining the study.

For this study the authors focused on the participants' coffee consumption: through the questionnaire the participants estimated their intake of both caffeinated and decaffeinated coffee by selecting 1 of 9 possible categories of increasing intake, from "never/seldom," and "1-3 servings/month," to "4-6 servings/day" or "6+ servings/day." For this study, a "serving" was defined as 50cc, or about 1.7 ounces (my American readers might best think of this as closer in amount to a "cup" of espresso than a "cup" of coffee).

For purposes of analysis, the estimates of consumption were collapsed into 4 categories of intake: less than 1 serving/day; 1 serving/day; less than 1 to less than 4 servings/day, and 4 or more servings/day.

The authors included nearly 20,000 men and women who participated in the average of 10 years of follow-up, comparing those who passed away during the follow-up period with those who did not. After taking into account age, Body Mass Index, alcohol consumption, physical activity level, and the participant's Mediterranean Diet score (among others), the researchers found that overall, "each additional 2 cups of coffee/d [regardless of whether they were caffeinated or decaffeinated] were associated with a significant 22% lower risk of all-cause mortality," with stronger associations seen in those over 55 years of age.

The authors note that the type of coffee consumed in Spain tends to be nonfiltered, made using pressure (such as espresso) or percolated (with boiling water passed over the coffee grounds). This affects the amount and type of antioxidants, acids, and other substances present in the coffee, thus implying that these results may not be relevant to those who consume mostly filtered coffee.

What this means for you

As always, observational studies such as these can only show association, not causation: there is no proof here that drinking coffee prevented death. Yet this is another small piece of evidence suggesting that not only is coffee not bad for you, it can certainly be part of a healthy diet.

First posted: November 28, 2018