Most of us know and love caffeine, the central nervous system stimulant that naturally occurs in coffee beans and gives our pour-overs and cold brews their energy-boosting magic. Something even the most seasoned coffee lover may not be aware of, though, is the fact that decaffeinated coffee, is not, in fact, 100 percent caffeine-free. That’s right, folks: There is caffeine in your decaf. GASP. Here’s what you need to know about why that is, how much caffeine we’re talking about, and whether it even matters.
Why there’s caffeine in decaf coffee
First things first: What the hell is caffeine even doing in your decaf cup of joe? She doesn’t even go here. We have the nature of the decaffeination process to thank for this. It’s long, complicated, and imperfect. “It is almost impossible to remove all the caffeine from a coffee bean,” Nathan Arnold, spokesperson for the Food and Drug Administration (FDA), tells SELF.
There are several methods of decaffeination, with the most common being what are called solvent extraction techniques, William Ristenpart, Ph.D., director of the U.C. Davis Coffee Center and professor of chemical engineering at the University of California Davis, tells SELF. Basically, after green coffee beans are harvested and dried but before roasting (which is when they turn brown), they are soaked in a solution containing a solvent, usually methylene chloride or ethyl acetate, which binds to the caffeine molecules and leaches them out. (By the way, if those chemicals sound a tad on the “should-I-really-be-putting-that-in-my-body” side, you can rest easy. While those chemicals might sound unsafe for sipping, only trace amounts remain at the end of the decaffeination and roasting process, Ristenpart says. Ethyl acetate is “generally recognized as safe” by the FDA. Methylene chloride is technically a potential carcinogen, but is present in such minuscule amounts in decaf coffee—at most, 10 parts per million, as regulated by the FDA since 1985—that it is not considered a risk to human health.) Other solvent methods involve drawing out the caffeine using only water (the Swiss water technique), or highly pressurized carbon dioxide (the supercritical carbon dioxide technique).
There are typically multiple rounds of extraction that take place. The number of rounds and the other steps and chemical processes involved in each method vary. But across the board, it is not feasible to remove every last molecule of caffeine, Ristenpart says. “In general, whenever you’re doing a separation of chemicals, it’s very difficult to achieve 100 percent [extraction], and that’s true for the caffeine in coffee beans.”
To explain why, let’s talk basic chemistry real quick. The amount of caffeine that can be extracted largely depends on how forcefully the solvents can pull those caffeine molecules out, Ristenpart explains. And the force the solvents can generate decreases as the beans are leached of their caffeine. This means that once the beans have gone through round after round of decaffeination, the beans contain less and less caffeine, which makes it increasingly more difficult to remove caffeine, Ristenpart says. “So you get diminishing returns…and the last bit is almost impossible to remove.”
How much caffeine is actually in decaf
An 8 oz cup of regular coffee typically has around 95 to 200 mg of caffeine, according to the U.S. National Library of Medicine. Decaf coffee typically only has between two and 15 milligrams per 8 oz cup, according to the FDA. As with regular coffee, there’s clearly a lot of variability here. “How much caffeine is in there by the time it gets to the consumer mostly depends on how much caffeine was present to start with,” which varies with different types of beans and growth regions, Ristenpart says. But it also depends on the technique and intensiveness of the decaffeination process a manufacturer uses, as well as the brewing method and strength, Ristenpart says.
In a study published in the Journal of Analytical Toxicology in 2006, researchers measured the caffeine content in 22 different cups of decaf coffee and espresso from a variety of brands, including Starbucks. They found that the caffeine content ranged from none detectable to 13.9 mg per 16 oz cup of decaf coffee (or about 7 mg per 8 oz cup), and three to 15.8 mg per shot of (decaffeinated) Starbucks espresso.
There are also no regulations specifying the maximum amount of caffeine coffee can contain in order to be labeled decaf, Arnold says. However, “As a general rule, the FDA has not objected to the use of the term ‘decaffeinated’ on coffee if at least 97 percent of the original caffeine has been removed,” Arnold explains. “The FDA believes that…is a good baseline.” (So, by that math, a bag of coffee beans that would’ve yielded an 8 oz cup with 150 mg of caffeine prior to the decaffeination process would serve up an 8 oz brew with no more than 4.5 mg of caffeine.)
Arnold also notes that in cases where the FDA does not have specific regulations, as with decaf, “we are mostly looking at labels that are truthful and not misleading.” But anyone trying to keep tabs on their caffeine intake for whatever reason will probably want to keep in mind that it’s not like a regulatory body is testing these things or holding coffee houses or manufacturers to their word. (And, to be fair, the FDA has more pressing concerns when it comes to what’s lurking in the food and drugs we consume.)
How big a deal a little caffeine actually is
The thing is, a few milligrams of caffeine is probably not enough to affect the majority of people, neurologist and sleep medicine specialist Ajay Sampat, M.D., assistant clinical professor at UC Davis Health, tells SELF. “When it’s such a small amount, most people are probably not going to experience noticeable effects.” Of course, this depends on a few factors, Dr. Sampat explains, like caffeine sensitivity (which is largely genetic) and caffeine tolerance (which develops with regular intake). Those of us who are mildly or moderately sensitive to caffeine and/or consume caffeine regularly are unlikely to be affected by the small amount of caffeine in decaf. And this is most of us.
But that doesn’t mean the caffeine in decaf is a non-issue to everybody. “For the minority of people who are really caffeine sensitive, even that small amount can be a lot,” Dr. Sampat says. Some people are naturally highly sensitive to caffeine. (Of course it’s likely that these people also avoid consuming caffeine regularly, so they probably have no or low tolerance, too.) So if you’ve ever noticed negative side effects of caffeine—a quickening heart rate or feeling jittery, anxious, nauseous, or restless, per the U.S. National Library of Medicine—after a cup of decaf (or regular coffee, for that matter), you may well be caffeine-sensitive. That’s why the FDA advises, “If you react strongly to caffeine in a negative way, you may want to avoid [decaffeinated coffee] beverages altogether.”
The tiny amount of caffeine in decaf could also be a potential issue for anyone trying to avoid or minimize caffeine intake due to a medical condition. That may include people with sleep disorders like insomnia, various liver diseases that cause impaired liver function, and migraine where caffeine is a trigger, Dr. Sampat says. And although caffeine can also potentially interfere or interact with various types of medications, Dr. Sampat says, it’s worth noting that these interactions have typically been observed with standard doses of caffeine, not the much-smaller quantities than found in decaf. If you have any concerns about how your caffeine intake could affect your health or if the caffeine content in decaf is something to think about, definitely ask your doctor about it to get their take.
When it comes to the issue of whether decaf can affect your sleep, specifically, the other most important variable to take into account is the time of day you drink it. Although the rate of caffeine metabolism and the length of its effects can vary widely from person to person, Dr. Sampat says, caffeine generally peaks within an hour and can linger in the body for four to six hours, according to the U.S. National Library of Medicine. So if a caffeine-sensitive person sips decaf at their 10 a.m. meeting, they’re not going to have an issue sleeping 12 hours later. But ordering decaf after dinner—which many people do, under the assumption their cup will be 100 percent caffeine-free—could pose a problem come bedtime, Dr. Sampat explains. (Although, again, the amount of caffeine may not even be enough to affect the person at all.)
By the way, there may also be some scenarios in which the small amount of caffeine in decaf is actually ideal. Say you’re trying to cut down on your caffeine consumption or wean yourself off the stuff entirely—or trying to stave off a caffeine headache in the late afternoon without tanking up on the stuff. In these situations, the minimal amount of caffeine in decaf could be just enough to get yourself through the day without face-planting on your desk. (But, again, whether that teensy hit of caffeine is enough to even register depends on your caffeine sensitivity and caffeine tolerance.)
The bottom line on caffeine in decaf
So, ultimately, whether or not the fact that there’s probably a bit of caffeine in your decaf affects you depends on a few things, like your caffeine sensitivity, tolerance, and medical history, as well as the time of day you drink it. Many people would never even realize they’re getting a mini-dose of caffeine—and if you’ve never noticed decaf having an impact on you, you’re probably one of them, and there’s no reason to change your decaf drinking habits now.
But if you have suspected before that there was something funny going on with your decaf, now you know you weren’t making things up—and that cutting down on your decaf could actually make a difference.