When Farin Kamangar was training as a physician in the 1980s, he asked patients about three lifestyle factors that could affect their health: alcohol, smoking and coffee. Though coffee didn’t have the same associations as smoking or drinking, Kamangar says, “the connotation was that this is not a good thing.”
Recently, though, coffee drinkers keep getting good news.
In 2026 alone, studies across disciplines have found that coffee could reduce dementia risk, protect your liver and improve your gut microbiome. Last year the U.S. Food and Drug Administration labeled black coffee as “healthy.” Kamangar, now an epidemiologist at Morgan State University, co-authored a 2025 literature review that drew on more than 100 studies and concluded “that moderate coffee intake is more beneficial than harmful across a wide range of health outcomes.”
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Just last week the American Heart Association (AHA) confirmed the beverage’s lack of harm—and its potential benefit—to heart health. Drinking up to five cups of caffeinated coffee a day, its authors wrote, has been linked to a lower risk of heart attack, diabetes, stroke and irregular heartbeat.
Gregory Marcus, a cardiologist at University of California, San Francisco, and lead author of the AHA statement, says his team has been “shocked” by the number of apparently positive effects of caffeinated coffee that scientists have found over the years.
“It’s remarkable how protective it is,” he says.
Coffee is the most consumed beverage in the U.S., with about two thirds of adults drinking it daily. People have been drinking coffee for centuries, and scientists have been studying its health effects for nearly as long. (Persian physicians were discussing coffee’s medicinal properties in the 900s C.E.!) Systematic studies of the relationship started back in the late 1940s. So, why does the research keep changing?
According to geneticist Marilyn Cornelis, scientists are simply conducting research better. Cornelis, who studies the genetics of how we metabolize caffeine at Northwestern University, first became interested in the subject two decades ago because of how many “inconsistencies” the research had. In the 1970s and 1980s, several studies found negative relationships between coffee and health, including a popular 1981 paper that found an association between coffee drinking and pancreatic cancer. The study interviewed around 1,000 patients at a hospital and found that those with pancreatic cancer drank more coffee—but many members of the control group had other medical issues that prevented them from drinking coffee at all. Subsequent studies, including one by the same research team, failed to replicate the results.
Historically, confounding factors also made it harder to track coffee’s health effects. People who smoke or have higher stress levels, for example, tend to both drink more coffee and have worse health outcomes. But in recent years, Cornelis says, “we’ve advanced in our statistical methods to account for that confounding.” And coffee drinkers rejoice!
Most recent studies on coffee have primarily focused on prospective cohorts; such investigations have followed tens of thousands of people for decades to track their habits and health outcomes. This type of evidence-based research has led to a “pendulum swing on caffeine,” Marcus says, and more accurately reflects the link between health and everyday habits.
“There’s a growing recognition that these common exposures, these lifestyle factors… are all in some way influencing our health,” he says.
Prospective cohort studies are not without their own drawbacks, though. It’s difficult to draw conclusions about caffeine more broadly because significantly more people drink coffee than other caffeinated beverages in these long-term observational studies, so researchers have far more data about coffee specifically. After reviewing hundreds of papers, the International Agency for Research on Cancer downgraded its official ranking of caffeine in 2016 from “possibly carcinogenic” to having a carcinogenicity to humans that’s “evaluated as unclassifiable.” But when it comes to other forms of caffeine, such as energy drinks, gaining popularity, the scientific story has barely begun—and scientists say we need far more data to understand how these types of caffeine sources relate to health.
Marcus, Kamangar and Cornelis all emphasize that it’s still important not to confuse correlation with cause—although modern studies are built to minimize ambiguity, it’s always possible that rather than coffee actually causing health effects, it could simply be consumed more commonly by people with certain health traits. It’s also crucial to not write off every person’s relationship to coffee as the same. As Marcus puts it, “I do worry, as both a scientist and a clinician, that it’s a natural tendency for us humans to want to see things as all good or all bad.”
Most of the studies that find positive associations have caveats. The AHA statement, for example, concludes that adding sugar or milk can increase calorie intake and counteract coffee’s potential health benefits, and many studies had found that drinking more than five cups of coffee a day isn’t associated with the same benefits. Individual metabolism and health can also determine just how healthy coffee is for each person.
For future research, scientists such as Marcus, Cornelis and Kamangar are curious about which of coffee’s thousands of compounds cause different health outcomes and what happens when non-coffee drinkers introduce the beverage into their diet. “Science in general is not a speedboat,” Kamangar says. “It’s a large ship that changes direction slowly. And especially since we are very risk averse, if somebody said in the 1980s that this is bad, it takes a lot of information to reverse that. We have gotten to a point that we have so much data from good studies that we can.”