People who drink around three cups of coffee a day may live longer than non-coffee drinkers, a landmark study has found.
The findings — published in the journal Annals of Internal Medicine — come from the largest study of its kind, in which scientists analyzed data from more than half a million people across 10 European countries to explore the effect of coffee consumption on risk of mortality.
Researchers from the International Agency for Research on Cancer (IARC) and Imperial College London found that higher levels of coffee consumption were associated with a reduced risk of death from all causes, particularly from circulatory diseases and diseases related to the digestive tract.
“We found that higher coffee consumption was associated with a lower risk of death from any cause, and specifically for circulatory diseases, and digestive diseases,” said lead author Marc Gunter of the IARC and formerly at Imperial’s School of Public Health. “Importantly, these results were similar across all of the 10 European countries, with variable coffee drinking habits and customs. Our study also offers important insights into the possible mechanisms for the beneficial health effects of coffee.”
Healthier livers, better glucose control
Using data from the EPIC study (European Prospective Investigation into Cancer and Nutrition), the group analysed data from 521,330 people from over the age of 35 from 10 EU countries, including the UK, France, Denmark and Italy. People’s diets were assessed using questionnaires and interviews, with the highest level of coffee consumption (by volume) reported in Denmark (900 mL per day) and lowest in Italy (approximately 92 mL per day). Those who drank more coffee were also more likely to be younger, to be smokers, drinkers, eat more meat and less fruit and vegetables.
After 16 years of follow up, almost 42,000 people in the study had died from a range of conditions including cancer, circulatory diseases, heart failure and stroke. Following careful statistical adjustments for lifestyle factors such as diet and smoking, the researchers found that the group with the highest consumption of coffee had a lower risk for all causes of death, compared to those who did not drink coffee.
They found that decaffeinated coffee had a similar effect.
In a subset of 14,000 people, they also analyzed metabolic biomarkers, and found that coffee drinkers may have healthier livers overall and better glucose control than non-coffee drinkers.
According to the group, more research is needed to find out which of the compounds in coffee may be giving a protective effect or potentially benefiting health.* Other avenues of research to explore could include intervention studies, looking at the effect of coffee drinking on health outcomes.
However, Gunter noted that “due to the limitations of observational research, we are not at the stage of recommending people to drink more or less coffee. That said, our results suggest that moderate coffee drinking is not detrimental to your health, and that incorporating coffee into your diet could have health benefits.”
The study was funded by the European Commission Directorate General for Health and Consumers and the IARC.
* Coffee contains a number of compounds that can interact with the body, including caffeine, diterpenes and antioxidants, and the ratios of these compounds can be affected by the variety of methods used to prepare coffee.
Abstract of Coffee Drinking and Mortality in 10 European Countries: A Multinational Cohort Study
Background: The relationship between coffee consumption and mortality in diverse European populations with variable coffee preparation methods is unclear.
Objective: To examine whether coffee consumption is associated with all-cause and cause-specific mortality.
Design: Prospective cohort study.
Setting: 10 European countries.
Participants: 521 330 persons enrolled in EPIC (European Prospective Investigation into Cancer and Nutrition).
Measurements: Hazard ratios (HRs) and 95% CIs estimated using multivariable Cox proportional hazards models. The association of coffee consumption with serum biomarkers of liver function, inflammation, and metabolic health was evaluated in the EPIC Biomarkers subcohort (n = 14 800).
Results: During a mean follow-up of 16.4 years, 41 693 deaths occurred. Compared with nonconsumers, participants in the highest quartile of coffee consumption had statistically significantly lower all-cause mortality (men: HR, 0.88 [95% CI, 0.82 to 0.95]; P for trend < 0.001; women: HR, 0.93 [CI, 0.87 to 0.98]; P for trend = 0.009). Inverse associations were also observed for digestive disease mortality for men (HR, 0.41 [CI, 0.32 to 0.54]; P for trend < 0.001) and women (HR, 0.60 [CI, 0.46 to 0.78]; P for trend < 0.001). Among women, there was a statistically significant inverse association of coffee drinking with circulatory disease mortality (HR, 0.78 [CI, 0.68 to 0.90]; P for trend < 0.001) and cerebrovascular disease mortality (HR, 0.70 [CI, 0.55 to 0.90]; P for trend = 0.002) and a positive association with ovarian cancer mortality (HR, 1.31 [CI, 1.07 to 1.61]; P for trend = 0.015). In the EPIC Biomarkers subcohort, higher coffee consumption was associated with lower serum alkaline phosphatase; alanine aminotransferase; aspartate aminotransferase; γ-glutamyltransferase; and, in women, C-reactive protein, lipoprotein(a), and glycated hemoglobin levels.
Limitations: Reverse causality may have biased the findings; however, results did not differ after exclusion of participants who died within 8 years of baseline. Coffee-drinking habits were assessed only once.
Coffee drinking was associated with reduced risk for death from various causes. This relationship did not vary by country.
Primary Funding Source:
European Commission Directorate-General for Health and Consumers and International Agency for Research on Cancer.
Abstract of Association of Coffee Consumption With Total and Cause-Specific Mortality Among Nonwhite Populations
Background: Coffee consumption has been associated with reduced risk for death in prospective cohort studies; however, data in nonwhites are sparse.
Objective: To examine the association of coffee consumption with risk for total and cause-specific death.
Design: The MEC (Multiethnic Cohort), a prospective population-based cohort study established between 1993 and 1996.
Setting: Hawaii and Los Angeles, California.
Participants: 185 855 African Americans, Native Hawaiians, Japanese Americans, Latinos, and whites aged 45 to 75 years at recruitment.
Measurements: Outcomes were total and cause-specific mortality between 1993 and 2012. Coffee intake was assessed at baseline by means of a validated food-frequency questionnaire.
Results: 58 397 participants died during 3 195 484 person-years of follow-up (average follow-up, 16.2 years). Compared with drinking no coffee, coffee consumption was associated with lower total mortality after adjustment for smoking and other potential confounders (1 cup per day: hazard ratio [HR], 0.88 [95% CI, 0.85 to 0.91]; 2 to 3 cups per day: HR, 0.82 [CI, 0.79 to 0.86]; ≥4 cups per day: HR, 0.82 [CI, 0.78 to 0.87]; Pfor trend < 0.001). Trends were similar between caffeinated and decaffeinated coffee. Significant inverse associations were observed in 4 ethnic groups; the association in Native Hawaiians did not reach statistical significance. Inverse associations were also seen in never-smokers, younger participants (<55 years), and those who had not previously reported a chronic disease. Among examined end points, inverse associations were observed for deaths due to heart disease, cancer, respiratory disease, stroke, diabetes, and kidney disease.
Limitation: Unmeasured confounding and measurement error, although sensitivity analysis suggested that neither was likely to affect results.
Conclusion: Higher consumption of coffee was associated with lower risk for death in African Americans, Japanese Americans, Latinos, and whites.
Primary Funding Source: National Cancer Institute.