Caffeine drinks are trendy, but are there some downsides? WebMD gets the perspective of experts.
By Kathleen Doheny
WebMD Weight Loss Clinic - Feature
Reviewed by Louise Chang, MD
If you crave caffeine to get you through the day, you're not alone. About 68% of Americans say they're hooked on coffee this year, compared with 64% last year, according to the National Coffee Association.
Sales of caffeine-laced energy drinks such as Red Bull and Monster are expected to rise 60% this year, says Gary Hemphill of the Beverage Marketing Corporation, a consulting firm in New York.
If those don't give you enough of a buzz, you can turn to sodas, coffee-flavored yogurt -- some of it has as much caffeine as a 12-ounce soda -- coffee ice cream, chocolate candy, or iced tea.
And one new product, controversially named Cocaine, goes one step further, offering a mega-dose of caffeine that dwarfs its nearest competitors.
Some medicines and dietary supplements for weight loss also include a dose of caffeine. Coke is even planning to roll out a new "negative calorie" carbonated green tea beverage this fall called Enviga that combines caffeine with other ingredients to -- according to the company -- increase calorie burning.
So what's the harm, ask caffeine fans, who point to studies showing the benefits of caffeine, such as boosting memory and improving concentration and perhaps lowering risks of diseases such as Alzheimer's and liver cancer.
But others are alarmed by what they say is an increasingly overcaffeinated nation; they are concerned by studies finding too much caffeine can set you up for high blood pressure, high blood sugar, and decreased bone density -- not to mention jangled nerves.
Caffeine abuse by young people alarms some experts. It was the cause of many calls to an Illinois Poison Center over a three-year tracking period, a team of doctors reported at the American College of Emergency Physicians annual meeting in New Orleans.
How Caffeine Works
"Caffeine exaggerates the stress response," says James D. Lane, PhD, professor of medical psychology at Duke University Medical Center in Durham, N.C., and a long-time caffeine researcher. "At the cellular level, caffeine locks the receptor normally used by adenosine, a brain modulator that provides feedback to avoid overstimulation of nerve cells. If adenosine is locked up, nothing keeps the nervous system from getting too excited at a cellular level."
People joke about being hooked on caffeine, but is it truly addictive? Researchers have debated that question for years.
"There's no question," says Roland R. Griffiths, PhD, professor in the departments of psychiatry and neuroscience at Johns Hopkins University School of Medicine in Baltimore and a veteran researcher in the area. Caffeine is addictive for some people, he says. "Caffeine does produce dependence, and caffeine withdrawal is a real syndrome."
But George Koob, PhD, professor of the Committee on the Neurobiology of Addictive Disorders at The Scripps Research Institute, San Diego, disagrees. "While it is possible to be addicted, most people are not," he says. "I think most of my colleagues would agree."
The Benefits of Caffeine
Caffeine can improve memory, decrease fatigue, improve your mental functioning, study after study suggests.
It can improve your short-term memory and speed up your reaction times, according to a study presented in 2005 at the Radiological Society of North America.
Moderate coffee consumption -- defined as three or four cups a day, providing 300 or 400 milligrams of caffeine -- carries "little evidence of health risks and some evidence of health benefits," conclude researchers from the Linus Pauling Institute at Oregon State University in Corvalis, writing in Critical Reviews in Food Science and Nutrition in March 2006.
Coffee drinking, the researchers say, may help prevent type 2 diabetes, Parkinson's disease, and liver disease, including liver cancer. And it doesn't appear to significantly increase heart disease risk or cancer. But, they warn, those with high blood pressure, as well as children, teens, and the elderly, may be more vulnerable to caffeine's adverse effects.
The Downsides of Caffeine
Caffeine does boost blood pressure, Lane and others have found. Although the rise is temporary, Lane questions whether it's good for you when it occurs over and over. After much research, he has concluded that repeated elevations in blood pressure and increases in your reactions to daily stress that occur with caffeine intake could boost the risk of heart disease. He worries, too, about the boost in blood glucose levels that accompanies caffeine intake.
Daily soft drink consumption may lower bone mineral density in women but not men, researchers from Tufts University reported in the October 2006 issue of the American Journal of Clinical Nutrition.
Caffeine abuse is an emerging problem, some experts say, especially as caffeine shows up in more products and in higher amounts. Soda sizes have gotten larger, the amount of caffeine in the so-called energy drinks has increased, and dietary supplements for weight loss often include caffeine.
The problem may be particularly prevalent among young people, according to a team of researchers from Northwestern University in Chicago. When they tracked calls to the Illinois Poison Center in Chicago for three years, they found that more than 250 cases of medical complications occurred from ingesting caffeine supplements and that 12% of the callers had to be hospitalized. The average age of the callers was 21. The researchers reported their findings at the annual meeting of the American College of Emergency Physicians in New Orleans.
"There are quite a few new energy drinks, and diet pills often use caffeine," says study researcher Danielle McCarthy, MD, a resident at Northwestern University. Often, she says, a doctor may not think to ask about these products when taking a medical history. Those who were hospitalized often had consumed other pharmaceutical products along with too much caffeine. Caffeine abuse symptoms include insomnia, tremors, nausea, vomiting, chest pains, and palpitations, among others, McCarthy says.
One of those new energy drinks, the previously mentioned Cocaine, is triggering protests not only for its name, but also because it contains far more caffeine and energy-boosting ingredients than competitors. Najee Ali, a Los Angeles activist who runs Project Islamic Hope, a national civil rights organization, has called for a boycott of the drink.
"It sends the wrong message to young, impressionable children," he says. "When you look at what is actually inside the drink, we have a greater concern. The drink is unhealthy. It has a lot of caffeine."
On its web site, the makers of Cocaine point out that consumers know the difference between an energy drink and a controlled substance.
"Hidden" caffeine is a growing danger, say scientists at the Center for Science in the Public Interest (CSPI), a nonprofit health advocacy organization. In 1997, the CSPI petitioned the FDA to label the caffeine content of foods, noting that the amount of caffeine varies widely among food products.
The caffeine content of 12-ounce soft drinks, for instance, varies from none to about 60 milligrams. "CSPI is in support of labels that tell the amount, in milligrams, of caffeine in foods and drinks," says spokeswoman Patti Truant.
No definitive action has been taken on the CSPI petition. Earlier this year, Neal D. Fortin, an attorney and professor of law at Michigan State University College of Law in East Lansing, and his food and drug law class also petitioned the FDA, asking for the same labeling requirements.
Even decaf coffee may contain caffeine, according to a University of Florida study published in the October issue of the Journal of Analytical Toxicology. Nearly all decaf contains some caffeine, the researchers reported, so that if someone drinks five to 10 cups of decaf a day, their caffeine intake could equal that in a cup or two of regular coffee.
So how to tread the line between moderate intake and too much?
"I think it has to be individualized," says Lane. "Some people are very sensitive, they can't even have a soft drink. Some people can drink coffee and fall right asleep. In general, people need to be aware of the kind of adverse effects caffeine can have. And if they are experiencing those, cut down or cut out caffeine."
Published Oct. 17, 2006.
SOURCES: Joe DeRupo, spokesman, National Coffee Association, New York City. Gary Hemphill, spokesman, Beverage Marketing Corporation, New York City. Patti Truant, spokeswoman, Center for Science in the Public Interest, Washington, D.C. American College of Emergency Physicians annual meeting, New Orleans, Oct. 15-18, 2006. James D. Lane, PhD, professor of medical psychology, Duke University Medical Center, Durham, N.C. Roland R. Griffiths, PhD, professor, departments of psychiatry and neuroscience, Johns Hopkins University School of Medicine, Baltimore. George Koob, PhD, professor of the Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, San Diego. Danielle McCarthy, MD, Northwestern University, Chicago. Najee Ali, Project Islamic Hope Los Angeles. Neal Fortin, professor of law, Michigan State University College of Law, East Lansing. Journal of Applied Toxicology, October 2006; vol 30: pp 611-613. Radiological Society of North America, Chicago, Dec. 1, 2005. Hiqdon, J.V. Critical Reviews in Food Science and Nutrition, March 2006; vol 46: pp 101-123. Tucker, K.L. American Journal of Clinical Nutrition, October 2006; vol 84: pp 936-942.
©2006 WebMD Inc. All rights reserved.