The line between caffeine and, well, everything else you can buy is a little blurry. At Starbucks, you can pick up CDs and a book about child soldiers with your espresso.
Now drugstore shelves, which once had few things caffeine-related, save perhaps the odd mug cozy or cappuccino-scented candle, are offering an array of skin care products containing the beloved stimulant.
The 20th century was a confusing time for caffeine. The Food and Drug Administration vacillated on whether it was good or bad for you. Sanka was created, but so was the Frappuccino. The new millennium, however, is shaping up to be a good one for it.
Over the last few years, studies have suggested that caffeine is capable of staving off baldness and lowering the risks of Parkinson's disease, among other wonders. And now, because of a boom in caffeinated topical agents, caffeine's possible benefits are accessible even to the 10 percent of the population that abstains from drinking it.
A source of energy
More than 140 cosmetic skin care products containing caffeine were released in the United States last year alone, compared with 21 in 2003, according to the Mintel Global New Products Database, a company that tracks trends in skin care products.
As any coffee drinker can attest, caffeine has two indubitable qualities: It is a stimulant and a diuretic. And these are the two main properties that companies are trying to transfer into topical lotions and potions.
The majority of products containing caffeine are skin-firming tonics that attempt to use its dehydrating qualities to decrease liquid in fat cells. While there are numerous facial firming products containing caffeine, such as eye creams by Kiehl's and Anthony Logistics for Men, most of the caffeinated lotions claim to be cellulite busters, including Bliss' Fat Girl Slim and Avon's Super Shape Anti-Cellulite and Stretch Mark Cream.
"There's a direct correlation between the increase in the amount of products that contain caffeine and the huge trend toward skin-firming products that work on cellulite, since so many of those products contain it," said Rachael McFarland, Mintel's cosmetic research analyst for the United States.
Many of these products entered the market after a 1999 study published in the American Society of Dermatologic Surgery concluded that caffeine-based liposome-encapsulated cream temporarily reduced the thickness of fat, particularly in the hips and triceps.
"The caffeine gets into the fat cell and this makes the fat cell get a little more energized," said Dr. Lawrence Moy, a dermatologist in Manhattan Beach, Calif., who was one of the study's authors and sells his own line of firming creams containing caffeine. "When fat cells get more energized, it affects the sodium-potassium balance in the cell. The sodium runs out of the cell and water leaves with it. Potassium runs into the cell and all this helps the cell to become a bit dehydrated and to shrink."
The layman's translation? It might make your legs look a bit less like cottage cheese, if only for a few hours.
Just skin deep
Of course, all this assumes that the caffeine can penetrate the skin once it's applied. According to a 2004 study conducted at the TNO Nutrition and Food Research center in the Netherlands, caffeine can indeed penetrate, at the rate of about 2 micrograms per centimeter squared per hour. That means it would take an hour for an amount 1/15th the size of a grain of salt to penetrate a fingernail-sized patch of skin.
Some companies would like you to believe that once it gets under the skin, it can make you feel like you just took a shot of espresso. V-tonic Bath Spheres by Fresh contains a cola-nut extract that the company promises will energize the skin, and Kiss My Face's Wake Up toothpaste has guaranine, a form of caffeine found in guarana seeds. But Mia DiFrancesco-Licata, a Kiss My Face spokeswoman, said: "It's such a small amount. It really just works subliminally."
But the idea that a simple daily ablution could help speed the waking-up process is appealing, especially in an on-the-go culture that guzzles products like Red Bull and supports a Dunkin' Donuts or a Starbucks on just about every corner.
"People are looking for more ways to jump-start the day now more than ever before," said McFarland of Mintel. "It's innovative and smart for companies to capitalize on that by creating more products that you'd use every day anyway, like soap, that just happen to also contain caffeine."
How much is enough?
But even if caffeine does enter the bloodstream via soap, the jury is out on whether enough of it can penetrate to make a difference in alertness.
"There is no way that enough caffeine could be absorbed through the skin during the amount of time that the average person showers," said Dr. David Bank, director of the Center for Dermatology, Cosmetic and Laser Surgery in Mount Kisco, N.Y.
The bloggers behind TheBeautyBrains.com, a cosmetics-debunking Web site written by a group of cosmetic chemists who remain anonymous to keep from jeopardizing their day jobs, used the TNO Nutrition and Food Research study to estimate that it would take an hour of full-body scrubbing - without rinsing - for a body to absorb the amount of caffeine in one cup of coffee.
Caffeine is an antioxidant that can combat cell damage caused by free radicals, which is one reason it is an ingredient in some sunscreens, Bank said.
It can be found in products like Rodan & Fields Essentials Protect SPF 30 and Origins Have a Nice Day Super-Charged Moisture Cream and Lotion SPF 15; these companies say it's there because of its antioxidant, anti-irritant and antiredness benefits. Dr. Allan Conney, a professor of chemical biology, leukemia and cancer research at Rutgers University, said users of any caffeine-rich cosmetic could also unwittingly be benefiting from a possible side effect that one study hinted at: They might be killing off existing skin cancer cells.
In 2002, the Proceedings of the National Academy of Science published a study led by Conney that used caffeine to kill off skin cancer sells on radiated mice. The results were promising, especially if you're a mouse living in a coffee urn.
"Although caffeine has a sunscreen effect, it also has a biological effect of causing apoptosis - programmed cell death - in UVB-damaged skin cells and in tumors but not in normal skin or in areas adjacent to tumors in tumor-bearing mice," Conney said in an e-mail message. "To the best of my knowledge, caffeine and caffeine sodium benzoate are the first examples of substances that have both a sunscreen effect and enhance cell death in a DNA-damaged tissue."
There is no proof that this effect can translate to human skin. Nevertheless, Conney and Bank are among the doctors open to the idea that one day a once lumpy thigh may also be one that is free of skin cancer.
But it might be just as effective to spend a couple of dollars at the cafe rather than on expensive lotions containing caffeine.
"You'd get the same effect from just drinking it," Conney said.