Specialty Coffee's Caffeine
Starbuck's Coffee Packs Twice as Much Caffeine as Dunkin Donuts'
By Jennifer Warner
WebMD Medical News
Reviewed By Michael Smith, MD
on Thursday, October 23, 2003
Oct. 23, 2003 -- The cup of Starbuck's coffee you drink on your way to work today may have twice as much caffeine as the one you bought yesterday.
A new study shows the caffeine content of specialty coffee beverages varies widely from day to day as well as from coffee shop to coffee shop.
Researchers found a medium (16 ounce) cup of the house blend at Starbucks packs an average of 259 milligrams of caffeine compared with only 143 milligrams in the same-sized cup of coffee at Dunkin Donuts.
But the same cup of coffee from a coffee chain such as Starbucks may also have widely varying amounts of caffeine from day to day. Researchers found that the caffeine content of a medium cup Starbucks Breakfast Blend coffee purchased from the same shop had caffeine levels ranging from 259 milligrams to 564 milligrams.
"I don't think people really know that there is a wide range in (coffee's) caffeine content," says researcher Bruce Goldberger, PhD, associate professor at the University of Florida College of Medicine, in a news release. "Our experience with specialty coffee is that it is not consistent."
Coffee Drinkers Face Caffeine Chaos
Researchers say that previous research has shown that the traditional five-ounce cup of coffee has about 85 milligrams of caffeine, and American adults consumed an average of about 200 milligrams of caffeine per day in 1978, with about 75% of that caffeine coming from coffee.
But this study, published in the October issue of the Journal of Analytical Toxicology, shows that larger coffee cups coupled with widely varying caffeine contents in popular coffees may be increasing American's caffeine consumption.
In the study, researchers evaluated the caffeine content of 20 caffeinated and seven decaffeinated specialty coffee and espresso samples from coffee shops in Maryland as well as six samples of Starbucks Breakfast Blend purchased during six consecutive days at a Gainesville, Fla., Starbucks coffee shop.
They found caffeine levels varied from 58 to 259 milligrams per serving. A single shot of Starbucks espresso had the lowest caffeine content at 58 milligrams, and a medium cup of the coffee chain's regular brew had the highest with 259 milligrams.
Even decaf coffee beverages weren't entirely caffeine-free, but none of the samples contained more than 18 milligrams of caffeine per 16-ounce serving.
Java's Caffeine Jolt Varies Naturally
In a written statement provided by Starbucks, spokeswoman Lara Wyss stated that there are many variables that contribute to caffeine content from cup to cup, such as the type of bean, roasting and brewing methods, and grind.
Researchers say that means coffee drinkers might have to live with uncertainty when it comes to how much caffeine their getting in their daily joe.
Caffeine is the world's most widely consumed drug and enhances performance by increasing alertness and speeding reaction time, but it can also speed up the heart rate and increase blood pressure and anxiety.
SOURCES: McCusker, R. Journal of Analytical Toxicology, October 2003; vol 27: pp 520-522. News release, University of Florida.
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