That's according to a new study that shows even decaffeinated coffee comes with at least a small dose of caffeine.
"If someone drinks five to 10 cups of decaffeinated coffee, the dose of caffeine could easily reach the level present in a cup or two of caffeinated coffee," says researcher Bruce A. Goldberger, PhD, of the University of Florida, in a news release.
Researchers say caffeine is the most widely consumed drug in the world, and coffee is a major source. Despite this, there are few guidelines about how much caffeine is too much, and even low doses may adversely affect some people.
People with certain medical conditions, including high blood pressure and heart arrhythmia, as well as those taking certain prescription medications are advised to avoid or limit caffeine.
In an effort to abstain from caffeine, many people turn to decaffeinated coffee, but researchers say they may be unaware that these decaf beverages also contain caffeine.
There's Caffeine in My Decaf!
In the study, published in the Journal of Analytical Toxicology, researchers set out to find out how much caffeine is likely to be found in popular decaffeinated coffees.
Researchers purchased 10 16-ounce decaffeinated cups of drip coffee from coffee shops and restaurants and analyzed them for caffeine content.
They found all but one -- decaffeinated Folgers Instant, purchased at a Krystal fast-food restaurant -- contained caffeine. The caffeine content ranged from 8.6 milligrams to 13.9 milligrams.
That's about a tenth of the caffeine found in an 8-ounce cup of regular drip-brewed coffee, which contains about 85 milligrams of caffeine.
Next, researchers tested several samples of decaffeinated espresso shots and decaf brewed coffee from the same Starbucks location to determine if caffeine content varied in the same drinks from the same location.
The results showed that the caffeine content of the decaffeinated espresso shots varied widely -- from 3 to nearly 16 milligrams; the caffeine content of the decaf brewed coffee ranged from 12 to 13.4 milligrams per 16-ounce serving.
Researchers say even though the caffeine content of decaffeinated coffees is low, people could develop a dependence on them.
"The important point is that decaffeinated is not the same as caffeine-free," says Roland Griffiths, PhD, a professor of behavioral biology and neuroscience at the Johns Hopkins School of Medicine, in the news release. "People who are trying to eliminate caffeine from their diet should be aware that popular espresso drinks such as lattes (which contain two shots of espresso) can deliver as much caffeine as a can of Coca-Cola -- about 31 milligrams."
SOURCES: McCuster, R. Journal of Analytical Toxicology, October 2006; vol 30: pp 611-613. News release, University of Florida.
By Jennifer Warner
Reviewed by Louise Chang