GAINESVILLE, Fla. - Does that cup of decaffeinated coffee give you a jolt? It
may, because almost all decaf coffee contains some caffeine, a new University of
Florida study shows.
The results could have implications for people told to avoid caffeine because
of certain medical conditions such as high blood pressure, kidney disease or
anxiety disorders, according to the study reported in this month's Journal of
Analytical Toxicology.
"If someone drinks five to 10 cups of decaffeinated coffee a day, the dose of
caffeine could easily reach the level in a cup or two of caffeinated coffee,"
said co-author Dr. Bruce Goldberger, a professor and director of the
university's William R. Maples Center for Forensic Medicine.
Researchers purchased 10 cups of 16-ounce drip-brewed coffee from nine
national chains and local coffee houses and tested them for caffeine content.
Instant decaffeinated Folgers Coffee Crystals didn't have any caffeine, but
the others contained caffeine ranging from 8.6 milligrams to 13.9 milligrams.
Typically, 16 ounces of drip-brewed coffee contain about 170 milligrams of
caffeine.
Researchers also analyzed 12 samples of Starbucks decaffeinated espresso and
brewed decaffeinated coffee. The espresso drinks had from 3 milligrams to 15.8
milligrams each, while the brewed coffee had from 12 to 13.4 milligrams per
16-ounce drink.
Even moderate caffeine levels can increase heart rate, blood pressure,
agitation and anxiety in some people, Goldberger said.
Dr. Roland Griffiths, a professor of behavioral biology and neuroscience at
Johns Hopkins School of Medicine, said caffeine as low as 10 milligrams can
cause behavioral effects in sensitive individuals. Some popular espresso drinks,
such as lattes, can deliver as much caffeine as a can of Coca-Cola, about 31
milligrams.
"The important point is that decaffeinated coffee is not the same as
caffeine-free," Griffiths said.
