Caffeine content of brewed coffee may vary widely

AORN Journal, Jan, 2004

Not all cups of caffeinated coffee are created equal, according to an Oct 22, 2003, news release from the University of Florida Health Science Center, Gainesville, Fla. Researchers who analyzed 16 oz servings of coffee from specialty coffee stores found that caffeine content varied widely from store to store and from cup to cup.

The average US adult consumes about 200 mg of caffeine per day, mainly from coffee. Moderate intake (ie, 250 mg per day) is not associated with any health risks, although caffeine consumption can increase heart rate, blood pressure, and anxiety, and caffeine is recognized as an addictive substance.

The study was conducted in two phases. In the first phase, researchers made a one-time purchase of 14 caffeinated brewed coffees, six espressos, and seven decaffeinated brewed coffees from six different retailers in two cities in Maryland. Chemical and mechanical methods were used to isolate the caffeine from the coffee samples, and caffeine content was measured using gas chromatography. Researchers found nearly twice as much caffeine in the strongest brew compared to the weakest--259 mg and 143 rag, respectively. Espresso servings ranged in size from 40 mL to 170 mL and contained between 58 mg and 185 mg of caffeine, with larger servings containing more caffeine. Each of the seven decaffeinated coffees contained some caffeine, although all contained Less than 18 mg per serving. The US Food and Drug Administration currently does not require that decaffeinated coffee be caffeine-free.

In the study's second phase, researchers purchased one blend of coffee at the same retailer in Gainesville for six consecutive days and analyzed caffeine content by the same method. During the six-day period, the caffeine content of this blend varied from 259 mg to 564 mg per serving.

According to researchers, this study demonstrates the need for retailers to inform consumers about the caffeine content in brewed coffee. This is a particularly important consideration for people who are monitoring their caffeine intake.

UF Study Finds Specialty Coffee's Caffeine Content Capricious (news release, Gainesville, Fla: University of Florida Health Science Center, Oct 22, 2003) http:// opi.health.ufl.edu/stories/2003/Oct/nordlie_102203_2.htm (accessed 29 Oct 2003).