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What you should know
People may not think of caffeine as the most popular mood-altering drug in the world, even those who use it daily, by drinking coffee, tea, sodas or energy drinks as part of their routine.
Yet many of us depend on regular doses of 1,3,7 trimethylxanthine, the chemical name for a bitter white powder known as caffeine, to help wake us up, keep us alert and get us through the daily grind.
Whether it's brewed from a K-Cup, sipped in sweet tea, savored in chocolate or downed in cola, caffeine is a mild stimulant to the central nervous system that has become a regular fixture in everyday life.
In moderate amounts, caffeine has been shown to have positive effects on people's bodies and minds. There's some evidence that caffeine may help improve memory, enhance workouts and boost concentration.
The Food and Drug Administration considers 400 milligrams a safe amount of caffeine for healthy adults to consume daily. However, pregnant women should limit their caffeine intake to 200 mg a day, according to the American College of Obstetricians and Gynecologists. (One cup of coffee usually has about 100 to 200 mg, a cup of tea usually has no more than 70 mg and most sodas have less than 50 mg, according to the Mayo Clinic.)
The Mayo Clinic suggests that teens limit their caffeine intake to 100 mg a day and recommends that younger children avoid caffeine. [5 Experts Answer: Is Caffeine Bad for Kids?]
Some people are highly sensitive to caffeine's effects. Caffeine can lead to headaches or an upset stomach, and may cause people to have trouble sleeping, feel jittery or get heart palpitations, when their intake is high (about four cups of coffee a day), studies (and anecdotal observations) suggest.
Here are 10 interesting facts about caffeine to mull over while nursing that first cup of joe.
Caffeine stays in the body for hoursSlide 2 of 21
Caffeine stays in the body for hours
Caffeine is absorbed into the blood and tissues within about 45 minutes of being consumed. But it takes much longer than that for the body to break it down and clear it from a person's system.
The half-life of caffeine, or the time it takes to eliminate one-half of the caffeine people have in their bodies, is about 4 hours, said James Lane, an emeritus professor of psychiatry at Duke University School of Medicine in Durham, North Carolina. But that doesn't mean that all of the caffeine is gone after 8 hours, in fact, it may take 12 hours to completely eliminate the caffeine in a morning cup of coffee, said Lane, who has studied the health effects of the drug.
Caffeine's half-life may be shortened to about 3 hours in people who smoke, Lane said. In contrast, women who take birth control pills may keep caffeine in their systems for up to 4 hours longer than women who are not on the pill, according to one study. [7 Surprising Facts About the Pill]
Pregnancy can extend caffeine's half-life even more, lengthening it to 10.5 hours during the final four weeks of pregnancy, according to one study.
Because it can take up to 12 hours to clear caffeine from the body, the drug often wears off when a person is almost ready to go to bed. This makes it easier for people to develop a dependency on caffeine because it makes people want to continue to drink it the next day, Lane said.
The reason people who regularly drink caffeine wake up feeling groggy, confused or with a headache is that they are experiencing withdrawal symptoms from yesterday's coffee, Lane said. These withdrawal symptoms are relieved when they get their morning fix of caffeine.Slide 3 of 21
Death from too much caffeine is rare, but possibleSlide 4 of 21
Death from too much caffeine is rare, but possible
In rare instances, when caffeine is consumed at high enough doses (typically in excess of 5 grams in adults — the amount in about 30 to 50 cups of coffee), it can kill.
Deaths have been reported from overdosing on powdered caffeine and caffeine pills, such as weight-loss aids. [7 Foods You Can Overdose On]
In 2014, two young men — an 18-year-old in Ohio and a 24-year-old in Georgia — overdosed on pure powdered caffeine, according to the FDA. Their deaths illustrate the dangers and potency of this concentrated product. One teaspoon of pure powdered caffeine contains about the same amount of caffeine as 28 cups of regular coffee, according to the FDA.
The FDA warns that young people, in particular, might use powdered caffeine — which is sold legally online — to boost their energy level, study longer, improve their athletic performance or lose weight.
But the powder is 100 percent caffeine, making it a powerful stimulant that, in even very small amounts, may trigger an accidental and potentially fatal overdose. Further complicating matters is that safe quantities of powdered caffeine can be nearly impossible to measure accurately with kitchen teaspoons, the FDA said.
Signs of caffeine toxicity might include a racing heart, sweating, seizures, vomiting, muscle tremors and, eventually, respiratory collapse, Lane said.Slide 5 of 21
It was involved in soda snafuSlide 6 of 21
It was involved in soda snafu
Although it contains less caffeine than a small cup of coffee, a 12-ounce can of Sunkist Orange soda has 41 milligrams of caffeine in it, according to the Center for Science in the Public Interest. Other brands of orange soda are usually noncaffeinated, but Sunkist Orange has more caffeine in it than a similar amount of Coca-Cola or Pepsi.
In September 2010, the makers of Sunkist Orange recalled nearly 4,000 cases of the 12-ounce bottled version of the beverage after receiving customer complaints that the soft drink had a medicinal taste to it and was causing stomachaches, vomiting and even hospitalization, according to the book "Caffeinated: How Our Daily Habit Helps, Hurts, and Hooks Us" (Hudson Street Press, 2014) by Murray Carpenter.
After looking into it, the manufacturer determined that human error was to blame for the incident: The reason for the off-taste and sickness was that a batch of the orange soda had been accidentally blended with six times as much caffeine as it should have, they said, according to the book.
Each bottle contained about 238 milligrams of caffeine, an amount equivalent to what's found in three Red Bulls, about seven cans of regular cola or 16 ounces of strong coffee, according to the book. Because orange soda is popular with kids, this high dose of caffeine possibly made a few children uncomfortable because they may not have realized why they felt that way.
Consumers were never informed of the supercaffeinated snafu because the FDA considered it a Class III recall, meaning "a situation in which exposure to the product is not likely to cause adverse health consequences," according to the book.Slide 7 of 21
Caffeine withdrawal is a real conditionSlide 8 of 21