Peter Shankman has an 8-liter-a-day-habit. Of Diet Pepsi, that is. Or, more precisely, caffeine. He has been known to soak tea bags in Pepsi for a week, then suck on them at the rate of about one an hour while slugging on a fresh 2-liter bottle of soda. When he works out, he uses a performance enhancer called Ripped Fuel. Main ingredient? Caffeine.
"I quit smoking seven weeks ago, and caffeine is pretty much all I have left," says Shankman, 28, president of the Geek Factory, a PR firm in Manhattan that represents high-tech companies.
It's barely noon, and he's already working on his fifth liter of the day. "I doubt I'll ever give it up," he says. "If it's the difference between drinking the soda or being really, really surly, I'm going to keep drinking the soda."
Shankman's habit may be extreme, but according to recent research, he may live just as long and just as well with his constant caffeine fix as he would without it. (OK, he could probably cut down a little.)
The average American consumes about 200 milligrams of caffeine a day, the rough equivalent of two cups of coffee. More than 90 million American adults drink caffeinated coffee on a daily basis -- a number that doesn't even begin to consider the children and adults who drink tea or soda, eat chocolate, take over-the-counter and prescription medications containing caffeine or find other ways to get their daily allowance of this central nervous system stimulant.
Caffeine can cause alertness, anxiety, fatigue or insomnia, depending on who you are and how much you use. And depending on what day of the week it is and what researcher you talk to, caffeine can be good, bad or indifferent. Lately, however, the chemical seems to be winning over the health sages.
Once thought to be a cause of various diseases, caffeine is now getting a clean bill of health. Look at cancer, for instance. Despite persistent beliefs that caffeine consumption can lead to pancreatic and breast cancers, "there's remarkably little evidence to suggest that caffeinated substances pose any risk of cancer," says Dr. Michael Thun, head of epidemiological research for the American Cancer Society.
To the contrary: There's some evidence that, because of its diuretic properties, caffeine may help lower the risk of bladder cancer and that certain teas, especially green tea, may have a general anti-cancer effect. Caffeine was also once thought to be linked with breast cancer. More recent research has found that this isn't the case, although caffeine can apparently contribute to the development of benign cysts and to breast pain, especially around the time of menstruation.
There has also been talk that caffeine contributes to the development of osteoporosis. Another myth, says the National Osteoporosis Foundation. Although caffeine can interfere somewhat with the absorption of calcium, this is easily offset by raising your calcium intake. An additional problem with adolescents is that so many of them drink soda (often caffeinated) instead of milk, and so don't get enough calcium in the first place.
The best recent news about caffeine appeared in the May issue of the Journal of the American Medical Association. Researchers found that higher coffee and caffeine intake (three large cups of coffee a day) was associated with a significantly lower incidence of Parkinson's disease among a group of Japanese-American men.
The problem with this study, and with many others involving caffeine, is that researchers don't know that the benefit comes from caffeine. It could have something to do with the personality type that is drawn to coffee, some other property of coffee or something else entirely.
Many heart studies have the same problem. It's difficult to isolate exactly what is causing the problem -- caffeine or something else. One link does seem to be definite, though: that between caffeine and hypertension. A study published in the May issue of the American Journal of Hypertension concluded that people with high blood pressure should avoid caffeine during high-stress situations at work, because it could push up their blood pressure even more.
"There's no doubt that caffeine in some patients is associated with a temporary high blood pressure response," says Dr. Richard Stein, a spokesman for the American Heart Association and chief of cardiology at Brooklyn Hospital Center. "It's also associated with rapid beating of the heart, which could be bad or make you very nervous."
Still, Stein maintains that the best reason not to drink 20 cups of Starbucks a day is to avoid what happens when you suddenly stop.
Giving up caffeine can be mighty unpleasant. Just ask Shankman. He usually gets a headache about 12 hours after his last fix. The next day, he says, his "tolerance for stupid people" takes a nose-dive, he snaps at his colleagues and he hurls himself in front of cabs without any regard for safety or decorum.