If contradicting research has you wondering if coffee is healthy or harmful, the answer is simple: it depends.
A recent study showed a benefit from drinking java on a population level. But it’s difficult to make individual recommendations for safe coffee consumption, said Dr. Ahmed El-Sohemy, a University of Toronto associate professor funded by the Canadian Institutes of Health Research who has studied caffeine and health.
El-Sohemy’s research has showed that coffee could either lower or raise a person’s risk of heart attack. That’s because safe daily coffee intake is going to vary with the ability to process caffeine - and that changes from person to person. There’s no easy way to tell how effectively your body deals with caffeine, and therefore how much of it is safe for you to drink, he said.
Because individual variations are hard to measure, it’s difficult to confidently recommend a safe amount of coffee consumption because what might be dangerous for one person could have no effect on another, El-Sohemy said.
That’s why numerous studies have associated coffee consumption with both an increased and a decreased risk for many chronic diseases, he said. Even for a single condition like heart disease, the findings have been inconsistent.
“You can sense the stimulating effects of caffeine when it binds to receptors in the nervous system,” he explained. “You cannot feel how quickly your liver is breaking down caffeine in your body, and there are no other signs or symptoms that tell you whether or not caffeine can trigger a heart attack in you.”
While the latest study, from the Universidad Autonoma de Madrid, did not prove that coffee is protective, its results strongly suggest that drinking coffee is not harmful to healthy individuals.
The researchers looked at thousands of healthy men and women from earlier studies and discovered that in the women, drinking two to three cups of coffee daily was associated with an 18 percent reduction in death from all causes, while four to five cups daily showed a risk reduction of 26 percent. The results in men were smaller and could have been due to chance, but followed similar trends.
Accounting for risk factors like weight, diet and smoking, the researchers found that people who drank coffee - caffeinated or decaf - were less likely to die than those who didn’t, and their risk reduction could be attributed to a lower risk of dying of heart disease, despite previous studies showing an association between heart disease and caffeine consumption.
The Universidad Autonoma de Madrid study involved thousands of individuals - 84,214 women from Harvard Nurse’s Health Study and 41,736 men from the companion study following male health professionals. A study of that size, which takes results from previous research and puts everyone into large groups, doesn’t take individual variations into account, El-Sohemy said. If the majority of the people in the study happened to be fast metabolizers of caffeine, you’d predict that the results would show a protective effect, and vice versa.
The consistent theme across all studies seems to be that when harmful effects like an increased risk of heart attack are associated with coffee, caffeine is the culprit, El-Sohemy said. Coffee naturally contains caffeine - about 100 mg in a single cup. Espresso also has 100 mg, and a grande latte or cappuccino at Starbucks has 150 mg.
Coffee is not the only drink with caffeine in it, however. A can of Coke or Diet Coke has 45.6 mg, and a single Red Bull energy drink has 80 mg. Tea can have caffeine as well, El-Sohemy points out - about 50 mg for black tea and 15 mg for green, depending on the blend and how long it’s steeped. Even decaf coffee still has a couple milligrams of caffeine in it.
The American Heart Association says the existing evidence pertaining to caffeine consumption and increased heart attack risk is conflicting. The AHA says that moderate coffee consumption of one to two cups daily doesn’t seem to be harmful. The Heart and Stroke Foundation agrees that moderate consumption is likely safe, but sets that level at two to three daily cups of beverages that contain caffeine, including coffee.
In the Universidad Autonoma de Madrid study, the protective effect that was associated with coffee consumption is probably not due to caffeine because a similar outcome was seen in decaf drinkers, El-Sohemy said, noting that the result is consistent with his own research on caffeine consumption.
“When it comes to heart attacks, caffeine is probably not a good thing,” he said. “It’s just that depending on the individual, it may come out as a significant risk or not really because it’s countered by some of these other compounds.”
Those include antioxidants like flavonoids. Foods rich in those compounds - including coffee, tea, dark chocolate, fruits and vegetables - have been associated with a lower risk of many chronic diseases. Antioxidant supplements, however, may not have the same impact, Al-Sohemy pointed out; in fact, some research suggests that supplements may produce an opposite oxidization effect.
On the individual level, coffee consumption may be a mix of the good and the bad: positive effects from antioxidants and other compounds, negative effects from caffeine.
“We need to really pay attention to individual recommendations,” El-Sohemy said. “It’s easy to make population-based recommendations, but ultimately the true risk or benefit will depend on the individual.”
Because there’s no easy way to know just who should be avoiding caffeine and who can consume it safely, switching to decaf coffee may be an option for some people who worry about health effects but enjoy their morning cup of joe.
“I think that might actually be a prudent thing to do,” El-Sohemy said. “And it looks like you may still be preserving some of these other goodies that are in coffee.”
By Terri Coles