Drink Coffee and You May Live Longer
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Two large new studies published today in Annals of Internal Medicine provide even more evidence that your daily coffee ritual is likely a very healthy habit. While most previous coffee research has involved primarily Caucasian individuals in the U.S., both studies looked at more diverse populations and found that drinking coffee (regular or decaf) was associated with a reduced risk of dying from any cause.
In one of the studies, the largest to include nonwhites, researchers from the Keck School of Medicine in Los Angeles tracked more than 185,000 African Americans, Japanese Americans, Latinos, Native Hawaiians, and whites for an average of 16 years. The results showed that you don’t have to overcaffeinate yourself to get the health benefits of coffee. Those who consumed just one cup a day were 12 percent less likely to die over the course of the study than people who did not drink coffee. Drinking two or more cups daily reduced the risk of dying by 18 percent. (The results could not be extended to Native Hawaiians, however, because there were too few of them in the study for the researchers to draw conclusions.)
“It’s really reassuring to see similar patterns across very diverse populations with different lifestyle and genetic susceptibilities,” says lead study author V. Wendy Setiawan, Ph.D., an associate professor of preventive medicine at the University of Southern California’s Keck School of Medicine.
The other study involved more than 520,000 men and women. All were Caucasian, but they were from 10 different European countries. Men who drank the equivalent of three or more cups per day were 18 percent less likely to die during the 16-year follow-up period than non-coffee drinkers; women had an 8 percent reduced risk. In particular, coffee users had a lower risk of dying from circulatory and liver diseases and had reduced levels of key liver enzymes that, when elevated, can be an indicator of liver disease.
Women who drank coffee also had more favorable levels of C-reactive protein (a marker of inflammation), HbA1c (an indicator of blood sugar control), and HDL cholesterol (“good” cholesterol) and lower levels of lipoprotein-a (a type of “bad” cholesterol associated with heart disease) compared to nondrinkers.
“A major strength of our study is that it included participants with widely varying dietary, lifestyle, and coffee drinking habits,” says lead co-author Neil Murphy, Ph.D., a scientist in the Section of Nutrition and Metabolism at the International Agency for Research on Cancer (part of the World Health Organization). The participants lived both in areas of Europe where people drink fewer but more concentrated drinks (such as espresso) and places where they drink many regular cups a day. They saw similar reductions in mortality risk despite the differences in preparation styles, coffee strength, and volume.
How Coffee Protects Your Health
In both studies, the benefits were similar among regular and decaf coffee drinkers. The protective effects of coffee may be due to its antioxidant and anti-inflammatory compounds, but researchers haven’t yet pinpointed the exact ones. “There are thousands of biologically active compounds in coffee and it’s hard to separate them,” says Setiawan. “The benefit could come from a combination of all these compounds working together.”
Although these studies don’t prove that coffee will prolong your life, they’re a step in that direction. The types of studies that would prove coffee definitely has an impact on various health risks (what researchers call causation) are almost impossible to do, says Edward Giovannucci, M.D., Ph.D., a researcher and professor of nutrition and epidemiology at Harvard’s T.H. Chan School of Public Health. “But when you can show that the benefit is consistent across diverse groups—men, women, different ethnicities and countries—like these studies have done, it adds to our confidence for causality.”
One limitation of both studies was their use of questionnaires. Self-reporting can be unreliable, says Giovannucci, plus it’s hard to account for exact serving sizes (a typical “cup” may be more or less than 8 ounces). The researchers did account for smoking, alcohol use, and other lifestyle factors that could sway the results.
Murphy says his team found no evidence that coffee drinking above a certain level is detrimental to health, but the Dietary Guidelines for Americans suggest limiting caffeine to 400 mg per day, about the amount in two to four 8-ounce cups of coffee. (The Food and Drug Administration says that 600 mg a day is too much.) “If you consume coffee and it’s part of your life, then you should be reassured that it’s probably not harmful and may even be beneficial,” says Giovannucci. “I wouldn’t necessarily recommend starting to drink lots of coffee, especially if it impacts your sleep, but it can be part of a healthy diet.”
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