What a difference a few years can make. Not long ago, I was learning about the dangers of coffee — how it could raise your blood pressure, make your heart race, impair sleep, and maybe even cause cancer.
Now, the World Health Organization (WHO) is taking coffee off the possible carcinogen list.
And there’s increasing evidence that coffee might actually be good for you. So good that doctors might begin recommending it.
What’s changed? It’s all about the evidence.
Possible health benefits of coffee
Over the last several decades, coffee has been among the most heavily studied dietary components. And the news is mostly good. Moderate coffee consumption (three to four cups per day) has been linked with longer lifespan. In fact, a November 2015 study in Circulation found that coffee consumption was associated with an 8% to 15% reduction in the risk of death (with larger reductions among those with higher coffee consumption). Other studies have found that coffee drinkers may have a reduced risk of:
- cardiovascular disease (including heart attack, heart failure, and stroke)
- type 2 diabetes
- Parkinson’s disease
- uterine and liver cancer
- cirrhosis
The reason that coffee drinking might be beneficial is unknown. One factor, of course, could be the caffeine, but that can be hard to sort out from the research because many studies do not distinguish whether the coffee is caffeinated or decaffeinated.
Possible health risks of coffee
A number of studies have linked coffee consumption to health problems, including:
- Bladder and pancreatic cancer. Studies performed more than 30 years ago suggested a potential link between coffee consumption and cancers of the bladder, pancreas, and possibly others. Since then, better research has largely refuted these concerns. In fact, some of the older studies raising red flags about a cancer link have since been used as examples of “fishing expeditions” and weak research methodology.
- Esophageal cancer. In its recently released report, the WHO has raised concerns that drinking coffee (or other beverages) at temperatures higher than 149° F (65o C) may increase the risk of esophageal cancer. However, this is not unique to coffee. And drinking coffee at such high temperatures is unusual among most coffee drinkers in the US.
- Cardiovascular disease. Studies linking coffee consumption to cardiovascular disease have mostly observed it with higher consumption (well above four cups per day), and some of these studies did not account for smoking, which often accompanies coffee consumption and is, of course, an important cardiovascular disease risk factor on its own. Other concerns include modest and temporary elevations in blood pressure, and fast or abnormal heart rhythms.
- Bothersome, but mostly minor, side effects. The caffeine in coffee can impair sleep, cause a “speedy” or jittery feeling, and even cause anxiety. Heartburn, frequent urination (because caffeine is a diuretic), and palpitations are problematic for some coffee drinkers.
A new move by the WHO… and others
In a June 2016 report, the WHO officially lifted coffee from the list of potentially carcinogenic foods. It went on to designate coffee as potentially protective against cancer of the uterus and liver.
And the WHO is not the only organization to include coffee in its list of foods that are probably harmless and possibly healthy. The 2015 Dietary Guidelines Advisory Committee (commissioned by the secretaries of the US Department of Health and Human Services and the US Department of Agriculture) thoroughly reviewed the evidence and declared that “moderate coffee consumption (three to five cups per day) can be incorporated into a healthy dietary pattern…” And the World Cancer Research Fund International concluded that coffee consumption was linked with a lower risk of several types of cancer.
Should you drink coffee?
Considering all of this good news about coffee consumption, you might feel tempted to increase your intake or to start drinking it if you don’t already.
Here’s my take:
- If you don’t like coffee, there is no current recommendation to drink it anyway. However, if we can figure out why coffee might have health benefits, it’s possible that a medication can be developed that provides those benefits without the side effects (or taste) of coffee or caffeine. Or, faced with a choice of a new medication or coffee, one might choose the latter.
- If you are already a coffee drinker, it should be reassuring that after decades of research, no strong link can be found between coffee intake and cancer and, to the contrary, a number of health benefits seem to accompany coffee consumption. But, I’m not sure the evidence is powerful enough to recommend an increase in your daily habit. One reason is that we don’t know for sure that coffee consumption actually caused the health benefits observed in these studies. Some other, unmeasured factor could be responsible. Another reason is that the overall effect was small. And, it’s worth noting that some people are quite sensitive to the side effects of coffee.
- Moderate your coffee intake. Although we don’t have proof that drinking six or more cups of coffee is dangerous, the risk of side effects is lower with moderation.
- Don’t drink beverages at very high temperatures (i.e., over 149° F). In addition to the potential risk of esophageal cancer, there is a risk of burning yourself.
In conclusion…
It’s unusual that a food on the “cancer risk list” comes off of it — and it’s even more unusual that such foods then become considered a healthy choice. But, as the millions of people drinking coffee every day will tell you, when it comes to coffee, there’s nothing like it.
Robert H. Shmerling, MD, Faculty Editor, Harvard Health Publications
