It’s a white, bitter-tasting crystalline powder. It’s an addictive drug. It has some of the same effects as heroin and cocaine. And it’s readily and legally available just about everywhere.
Don’t call the cops. It’s caffeine, and if you haven’t had any today, you’re in the minority.
Tea has been imbibed by the Chinese for thousands of years, and it would be remarkable if, in all that time, no one noticed that too much of it keeps you awake. But caffeine wasn’t isolated until 1820.
A young analytical chemist, Friedrich Ferdinand Runge, had managed to analyze some of the effects of belladonna extract. This impressed famed German writer, philosopher and coffee drinker Johann Wolfgang von Goethe, who in 1819 invited Runge to visit him. Impressed by Runge’s techniques, Goethe urged him to analyze coffee, and even provided some rare Arabian coffee beans. Within a year, Runge, still in his mid-20s, had successfully extracted pure caffeine.
The plants that produce caffeine do so because it kills or paralyzes insects that try to feed on them. Fortunately, it doesn’t have quite the same effect on humans.
Ordinarily, when we stay awake a long time, we become drowsy because a brain chemical called adenosine binds to special receptors on nerve cells in our brains. Molecularly, caffeine is close enough in structure to adenosine that it can bind to those same receptors, leaving no place for the adenosine—or the drowsiness it generates.
Adenosine slows nerve cell activity and causes blood vessels to dilate. By blocking its action, caffeine in effect speeds nerve cell activity and contracts blood vessels. The increase in nerve activity in the brain is read as signs the body needs to be ready for action by the pituitary gland, which responds by releasing hormones to notify the adrenal glands to produce adrenaline. Adrenaline, in turn, causes our pupils to dilate, our breathing tubes to open up and our hearts to beat faster. Surface blood vessels contract and blood pressure rises, less blood flows to the stomach, more sugar is released into the bloodstream by the liver, and muscles tense up, ready for “fight or flight.”
A hefty dose of caffeine, in other words, is roughly equivalent to coming face to face with a bear in the woods.
Caffeine also increases the level of another brain chemical, dopamine, in exactly the same way (though not nearly as strongly) as amphetamines. Dopamine activates feelings of pleasure in certain parts of the brain. This probably contributes to caffeine addiction in those so afflicted.
It takes about six hours for half the caffeine in your body to metabolize. If you drink a big cup of coffee with 200 mg of caffeine in it at your 3 p.m. coffee break, half of it, 100 mg, the equivalent of a small cup of coffee, will still be acting on your body at 9 p.m., when you may be getting ready for bed. Even if you fall asleep, you may not sleep deeply, which will contribute to a sleep deficit over time…which makes you sleepy during the day, which makes you drink more caffeine.
Is it bad for you? Well, a survey of Dutch men and women suggested that heavy coffee drinkers had a lower risk for Type 2 diabetes, and a 2005 study found higher levels of some cholesterols in the blood of drinkers of decaffeinated coffee.
Now it appears it may come down to heredity. A new study led by Ahmed El-Sohemy at the University of Toronto, released this week, indicates that for people who are genetically able to metabolize caffeine quickly, coffee may be beneficial, whereas for those who are genetically programmed to be slow caffeine metabolizers, caffeine consumption increases the risk of heart attack.
Specifically, the study’s results indicate slow caffeine metabolizers have a 36-percent greater risk of heart attack if they drink two or three cups of coffee a day than people with the same gene who drink a cup or less a day. Their risk is 64 percent greater if they drink four or more cups a day. But speedy caffeine metabolizers actually have a 22-percent lower risk of heart attack if they drink three to four cups a day than others of their genetic makeup who drink just one cup a day.
The researchers theorize that high levels of caffeine continually circulating in the blood may keep the blood vessels restricted, increasing the risk of a heart attack. But, they also say, more research is needed.
Just one question they didn’t answer: how many cups a day did the researchers drink?
