Hidden Caffeine in Food and Drink: Do You Know What You Are Consuming?
National Geographic

Did you know?

Guarana: Hidden Caffeine

Guarana is an ingredient found in many sodas, energy drinks, protein bars, and natural weight-loss aids. It comes from the seeds of a woody vine native to Brazil named for an Amazonian people, the Guarani, who process the seeds for use in food, drink, and medicine. What might be a surprise is that guarana contains concentrations of naturally occurring caffeine higher than that found in coffee, tea, cacao, and kola. Guarana sodas are immensely popular in South America, especially Brazil, and the stimulant is finding its way into more and more energy drinks. Guarana is sometimes marketed as a natural alternative to caffeine, but it's caffeine all the same. Look at the labels of some energy drinks and you'll see both caffeine and guarana, which means that you're getting caffeine from two sources.
 

Rethinking Caffeine

Scientists have developed various theories to explain caffeine's "wake-promoting" power. The consensus today focuses on the drug's interference with adenosine, a chemical in the body that acts as a natural sleeping pill. Caffeine blocks the hypnotic effect of adenosine and keeps us from falling asleep. Since caffeine has also been shown to enhance mood and increase alertness in moderate amounts, it's a potent potion for students and scholars stuck in the lab at three in the morning. Paul Erdős, the Hungarian mathematician who often worked his equations around the clock, is known for saying that "a mathematician is a machine for turning coffee into theorems."

..."Caffeine helps people try to wrest control away from the human circadian rhythm that is hardwired in all of us," says Czeisler. But then a shadow crosses the doctor's sunny face, and his tone changes sharply. "On the other hand," he says solemnly, "there is a heavy, heavy price that has been paid for all this extra wakefulness." Without adequate sleep—the conventional eight hours out of each 24 is about right—the human body will not function at its best, physically, mentally, or emotionally, the doctor says. "As a society, we are tremendously sleep deprived."
 
In fact, the professor goes on, there is a sort of catch-22 at the heart of the modern craving for caffeine. "The principal reason that caffeine is used around the world is to promote wakefulness," Czeisler says. "But the principal reason that people need that crutch is inadequate sleep. Think about that: We use caffeine to make up for a sleep deficit that is largely the result of using caffeine."

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