Want to live a long and healthy life? Drink a few cups of coffee every day. That’s the gist of a recent meta-analysis published in the European Journal of Epidemiology. People who drink 2 to 4 cups of coffee a day have reduced all-cause mortality and reduced cause-specific mortality compared with people who drink no coffee—even when factors such as age, weight, smoking, and drinking alcohol are taken into account.
The link between lower mortality and coffee consumption even holds true no matter if it’s decaf or regular.
How much coffee must you drink to get the benefits? The researchers determined that the ideal amount is 3.5 cups of coffee per day to get the greatest risk reduction—15%—in all-cause mortality. For cardiovascular disease (CVD) mortality, 2.5 cups reduce risk the most, by 17%. And 2 cups per day is associated with the lowest relative risk in cancer mortality—4%—compared with drinking no coffee.
You can stop at 3.5 cups a day, though. Drinking more coffee than this won’t increase your longevity any further, the researchers found.
Adjusting for other factors
For this analysis, the authors reviewed 40 studies that included a total of 3,852,651 participants. Because they had a large number of studies, the researchers were able to investigate associations between coffee consumption and all-cause mortality for a variety of factors, such as age, sex, geographic region, overweight status, alcohol consumption, and smoking status.
But, it turned out that most of these factors made no difference on coffee’s relation to reduced mortality.
“The inverse association between coffee drinking and all-cause mortality was consistent in various subpopulations by overweight status, alcohol consumption, smoking status and by caffeine content of coffee,” the authors wrote.
What’s in that magic elixir?
Coffee contains more than 1,000 bioactive substances, including caffeine, chlorogenic acids, and diterpenes. But, the researchers speculate that certain antioxidant and anti-inflammatory compounds are the ones responsible for lowering mortality risk.
“Coffee contains various antioxidant components such as caffeine, chlorogenic acid, melanoidins, cafestol, kahweol, and trigonelline,” which may prevent oxidative damage, wrote Youjin Je, ScD, assistant professor, Department of Food and Nutrition, Kyung Hee University, Seoul, South Korea, and co-authors.
“Many human studies also have shown that coffee intake may be associated with the levels of pro-inflammatory biomarkers including tumor necrosis factor-alpha, C-reactive protein, and interleukin 18, and increase the levels of anti-inflammatory biomarkers such as adiponectin,” they added. “These antioxidant and anti-inflammatory properties of coffee compounds may lead to a decreased risk of mortality through slowing the development of some major chronic diseases including diabetes, CVD, and cancers.”
Among those other major diseases, the researchers found that people who drank the most coffee had a 24% lower risk of mortality from diabetes, a 10% lower risk from respiratory disease, and a 35% lower risk from non-CVD, non-cancer causes, compared with people who drank the least amount of coffee.
Mortality risk differed by geographic region, the researchers found. Coffee-drinkers in Europe and Asia had lower risks of mortality than those in the United States.
Closer to conclusive
The authors acknowledged a few limitations to their analysis. For one, the studies they reviewed were observational, so they could not conclude that coffee directly causes reduced mortality. Also, participants self-reported their coffee consumption on questionnaires, which may not be perfectly reliable.
Going forward, Dr. Je and co-authors called for additional, more detailed investigations to further strengthen the link between coffee and reduced mortality.
“Future large prospective studies with detailed information of coffee preparation, sugar and cream added to coffee, or genotype of population could provide a more definitive conclusion on the potential effects of coffee intake on risk of mortality,” they wrote.
This research was supported by the Basic Science Research Program through the National Research Foundation of Korea, and by the Ministry of Science, ICT, and Future Planning.