If you’re like most people, you probably reach for a cup of coffee (or several) every day. Maybe you even smugly share articles about the benefits of coffee while sipping out of your favorite “don’t talk to me until I’ve had my coffee” mug. If so, you’re probably thrilled about two new studies recently published in the Annals of Internal Medicine that suggest coffee may help you live longer. But…it’s a little more complicated than that, of course.
First, let’s dig into what these studies found out about your coffee habit.
One study examined more than 520,000 people in 10 European countries and found that people in the highest coffee-consumption group also had the lowest rate of mortality. When they dove a little deeper, the researchers also found that there was a statistically significant link between drinking coffee and a lowered risk of dying from heart disease or stroke in women. Both male and female coffee drinkers also had a decreased risk of dying from a digestive disease.
The other study looked at more than 185,000 African Americans, Native Americans, Hawaiians, Japanese-Americans, Latinos, and Caucasians, and found that, in most cases, drinking coffee was linked to a longer life (Hawaiians were the only outliers). Specifically, people who drank two to four cups a day had an 18 percent lower risk of death compared with people who did not drink coffee. They also had a lower risk of death from heart disease, cancer, respiratory disease, stroke, diabetes, and kidney disease.
Of course, correlation does not equal causation. Meaning, we can’t say that drinking coffee causes people to live longer—just that it’s associated with living longer.
In the European study, researchers point out that reverse causality could have come into play, meaning that it’s possible that people who live longer just happen to prefer coffee, versus coffee actually causing them to live longer. They also point out that the coffee-drinking habits of study participants were only taken once. So, it’s possible people could have just happened to have gone through a coffee-heavy phase during the study, only to change their habits later. In the second study, researchers say it’s possible that there were confounding variables (i.e. other factors that can impact the results) that they didn’t catch. For instance, maybe coffee drinkers are also more likely to exercise, which could also affect your mortality risk.
It’s worth pointing out that this isn’t the first time science has linked coffee with good health. A Harvard University study published in 2015 analyzed the coffee consumption of more than 208,000 people over 30 years, as well as their cause of death and discovered that people who drank one to five cups of decaf or regular coffee a day had a lower risk of mortality than those who didn’t. Those coffee drinkers were less likely to die from heart disease, neurological diseases, Type 2 diabetes, and suicide. A meta-analysis of 36 studies published in the journal Circulation in 2014 also found that people who drink three to five cups of coffee a day were at the lowest risk of developing heart disease. Still, we’re not able to say that coffee is what’s really causing people to live longer.
“The question that really remains is why? ”Anton Bilchik, M.D., Ph.D., professor of surgery and chief of gastrointestinal research at John Wayne Cancer Institute at Providence Saint John’s Health Center in Santa Monica, California, tells SELF. The researchers offer some explanations that drinking coffee may improve liver function and reduce inflammation, and Dr. Bilchik says these are important factors when it comes to reducing your risk of developing cancer as well as heart disease. “There is a large area of research right now regarding heart disease and cancer, and how they relate to inflammation—it’s certainly possible that drinking coffee may reduce inflammation that takes place in the body and it may be protective,” he says. However, this link hasn’t been proven yet.
So you can’t just rely on your three-cups-a-day to extend your life. But, sure, you might be able to count that as one of your daily habits that are associated with living a long and healthy life.
There are several factors that go into reducing your overall disease risk, including eating well, avoiding smoking, and exercising regularly, Jack Jacoub, M.D., an internist, medical oncologist and medical director of MemorialCare Cancer Institute at Orange Coast Memorial Medical Center in Fountain Valley, California, tells SELF. “People reduce their mortality rate by doing various things—this could be one of them,” he says. “There has already been a pretty clear message that there might be some positive effects from drinking coffee. These very large studies provide even more supportive evidence.”
That said, drinking coffee has a few known side effects that are also important to factor in. Having too much caffeine, which is found in regular coffee and even decaf to some extent, can increase a person’s heart rate and possibly cause irregular heart activity that could be dangerous to those who already have heart problems, Morton Tavel, M.D., a clinical professor of medicine at the Indiana University School of Medicine, tells SELF. It can also cause hyperactivity, headaches, and agitation, Dr. Bilchik points out, as well as exacerbate acid reflux in people with digestive issues. The caffeine in coffee can also make some people feel lightheaded and dizzy, and drinking a lot of coffee could dehydrate you, Dr. Jacoub says. “But if you don’t have those issues, I think the data continues to build on itself that it’s good to drink coffee,” he says.
Ultimately, Dr. Bilchik says that drinking coffee in moderation is safe and even seems to have a beneficial effect. But, if it’s not your thing, that’s OK, too—it’s not the end-all, be-all to longevity.