Could America’s favorite way to start the day be quietly harming our health? The last week has seen a lot of buzz about whether coffee—long thought to confer health benefits—might actually contain cancer-causing compounds. As you may have read, a nonprofit group called the Council for Education and Research on Toxics recently sued 91 coffee companies, including Starbucks, for failure to warn their consumers about a potentially carcinogenic compound found in the brew.
And last Wednesday, a judge in California ruled in the group’s favor, stating that all coffee sellers must add a cancer warning label to their beverages. The reactions to this ruling have run the spectrum from concern to skepticism to accusations of alarmism. So does coffee really cause cancer, or has the lawsuit created needless worry?
What Do the Studies Say?
The potentially cancer-causing compound in question is called acrylamide, a chemical that’s formed when coffee beans are roasted. It also appears in other foods that have been heated for a long period of time, like French fries and potato chips, as well as cigarette smoke. It’s classified as a “probable” or “likely” carcinogen, based on animal studies—but those studies are not necessarily relevant or generalizable to humans. Plus, many of those studies used doses of acrylamide between 1,000 and 10,000 times the level to which a human would be exposed. According to the American Cancer Society, studies have not yet found a link between exposure to dietary acrylamide and cancer risk.
Moreover, a review of more than 1,000 studies failed to find any correlation between coffee consumption and any type of cancer. In fact, studies have repeatedly found that moderate coffee consumption may actually confer health benefits—from a reduced risk of heart disease, diabetes, and stroke to protection against Alzheimer’s disease and cognitive decline (and even, in some cases, a reduced risk of cancer).
How Conclusive are the Results?
To date, most of the studies on coffee and human health (whether positive or negative) are observational. This means that they require participants to accurately recall what they ate and drank and in what quantities, so that researchers can look for associations between nutrients or foods of concern and certain outcomes like cancer. While these types of studies can show us correlation, they fail to show causation, which is a much more valuable predictive tool of health. Plus, observational studies like these rely on the accurate recall of a person’s diet, which is notoriously difficult (try to remember everything you ate yesterday, down to every grain of salt and handful of chips!).
The real gold standard in any research setting is a randomized clinical trial (RCT). In these studies, a large number of participants are randomly selected to one of two groups, a coffee-drinking group and a no-coffee group. Researchers then follow each group, and after a certain amount of time, they evaluate outcomes (in this case, the absence or presence of cancer) in each group and generate conclusions based on what they find. But until more RTC’s are conducted, coffee research remains insufficient.
So What Does That Mean for Me?
So can—or should—you still drink coffee? Sure, if you enjoy it. Drink a few cups a day, provided it doesn’t make you feel anxious or jittery. And if you don’t enjoy coffee, that’s fine too! But the real takeaway to these headlines is not that coffee is good or coffee is bad—it’s that nutrition research is constantly evolving and notoriously difficult to study, and attention-grabbing headlines like these are almost always reactionary and overblown.