Good news, coffee drinkers: A couple of massive new studies that looked at hundreds of thousands of people for about 16 years finds that a few cups of coffee a day won’t hurt you and could lower your risk of dying prematurely.
The studies reinforce previous findings that drinking an 8-ounce cup of joe (or three) won’t hurt you, but the authors of the new works and other experts say caveats abound.
“Our results suggest that moderate coffee drinking, up to about three cups a day, is not harmful to your health, and that incorporating coffee into your diet could have health benefits,” said Neil Murphy, of the World Health Organization, a lead author on one of two studies published Monday in the Annals of Internal Medicine. “[We] found no evidence that coffee drinking above a certain level is detrimental to health.”
Murphy told STAT his is the largest study on coffee and mortality to date.
In the study, researchers with the WHO’s International Agency for Research on Cancer and Imperial College London tracked 521,000 adults from 10 European countries who self-reported their coffee consumption over an average of 16 years. They looked for associations between the amount of coffee consumed and various health indications, but it’s not a cause-and-effect relationship. In investigating more than 40,000 deaths from this group, the team found that participants who fell into the highest 25 percent of coffee consumers had a lower risk of death due to any cause compared to non-coffee drinkers. They saw a reduced risk of early death by diseases related to the digestive and circulatory systems. The researchers also discovered a link between higher coffee consumption and lower risk of early death by lung cancer in men.
And they also looked at suicide — completed suicides were lower for coffee drinkers, but only in men.
In a second study of 180,000 people tracked for an average of 16 years, University of Southern California investigators found drinking one to six cups of coffee per week led to a decreased risk of early death. The study was focused on non-white populations, and their findings proved consistent for coffee drinkers across racial and ethnic groups.
Both studies adjusted findings to take into account that people who drink larger amounts of coffee are likely to smoke tobacco products as well.
One of the USC study’s senior authors, V. Wendy Setiawan, an assistant professor at Keck School of Medicine, said coffee consumption may be linked a lower risk of early death for people with heart disease, cancer, chronic lower respiratory disease, stroke, and kidney disease. Drink one cup per day, and the risk of dying early from those diseases decreases by 12 percent, she said.
However, Setiawan said the study didn’t find the same relationship between coffee and deaths related to influenza, pneumonia, Alzheimer’s disease, or intentional self-harm.
Dr. Eliseo Guallar, an epidemiologist with Johns Hopkins Bloomberg School of Public Health who was not involved in the study, wrote in an editorial accompanying the studies that he’s hesitant to draw too many positive conclusions about coffee’s health. “Recommending coffee intake to reduce mortality or prevent chronic disease would be premature,” he wrote.
Setiawan, like Murphy and Guallar, is cautious about hype.
“We cannot say coffee will prolong your life,” Setiawan said. “We can say moderate coffee consumption can be incorporated into diet for a healthy lifestyle. For most, it seems, it likely won’t cause harm.”