There's a lot of buzz lately about caffeine, from studies about how it affects health to new super-octane beverages that pledge to give you a morning boost, improve your athletic performance and help you lose weight.
Caffeine has even made the leap to soap (it's absorbed through the skin, according to its manufacturer), gum and pancake syrup. As products proliferate and the caffeine gauge edges higher, a question begs to be answered: How much caffeine can we take?
Caffeine is a central-nervous-system stimulant that occurs naturally in at least 63 plants. When ingested, it blocks adenosine, a chemical that slows brain activity. That results in alertness and heightened concentration. The effect peaks in 30 to 60 minutes, then tapers off.
Published data shows the per-capita consumption level of caffeine for the average adult is about 200 milligrams daily.
Most health-care professionals consider about 250 to 300 milligrams to be a moderate daily dose. Go beyond that, and you may feel shaky, jittery or anxious and have trouble concentrating or sleeping, says Cynthia Sass, a registered dietitian in Tampa. You also could temporarily suffer from elevated blood pressure or an irregular heartbeat.
There's probably no reason for alarm if you consume moderate amounts of caffeine, though.
"Luckily, research shows that the danger and risks [of caffeine] seem to be very minimal, even when consumed in large amounts," says Dr. George Everett, who practices internal medicine at Orlando Regional Healthcare.
Those with heart disease and high blood pressure, though, should watch their intake.
Caffeine is one of the most-studied ingredients in the U.S., according to the Food and Drug Administration, which declared it generally safe in 1958. While science has cleared it of contributing to things such as bone loss, birth defects and chronic hypertension, use of the substance still may have ramifications. For instance, a study released in March suggested that a genetic trait that slows the metabolism of caffeine might increase the risk of heart attacks.
Reaction to caffeine usually is dictated by factors such as an individual's size and how much he or she regularly consumes, Everett says. Larger people can tolerate more caffeine than smaller ones, and an infrequent caffeine user is more likely to react strongly than one who uses it daily.
Quitting caffeine suddenly can lead to painful withdrawal, with symptoms including a migraine-like headache, inability to concentrate, nausea and irritability.
During the past decade, the popularity of caffeinated energy drinks--such as Jolt, Vault, SoBe Adrenaline Rush and Full Throttle--has increased dramatically. According to marketresearch.com, this market segment grew 700 percent between 2000 and 2005.
The energy drinks' actual caffeine content usually is lower than a weak cup of coffee, which has about 85 milligrams. Coca-Cola's Full Throttle, for instance, has 72 milligrams per 8 ounces. Energy-drink manufacturers, however, usually pair the ingredient with things such as sugar, herbal stimulants (guarana and ginseng) and taurine, an amino acid that enhances the effect of caffeine.
Though some energy drinks are marketed to athletes, "I really don't think most active, fit adults need the extra calories" they deliver, says Christine Gerbstadt, a doctor and an American Dietetic Association spokeswoman.
BEHIND THE BUZZ
The FDA doesn't require that caffeine be listed on product labels because it has no nutritional value. If the stimulant occurs naturally in a product--as it does, say, in a coffee bean--it doesn't have to be listed as an ingredient. The FDA recommends calling a product's manufacturer to learn its caffeine content. Some Web sites also can help you tally your intake. The Mayo Clinic's Web site (mayoclinic.com), for instance, provides the caffeine content of popular energy and soft drinks.
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