By Catherine Crépeau – The Rumor Detectors
Agence Science-Presse (www.sciencepresse.qc.ca)
Big coffee drinkers are often told to lower their caffeine consumption by drinking tea so they’ll sleep better. But isn’t tea also a stimulant? The Rumor Detectors checked this one out.
Caffeine is the most studied and most consumed stimulant in the world. It is present in a number of drinks, including coffee, hot chocolate, colas… and yes, even in tea. In effect, the theine contained in tea is the same as caffeine in coffee. They are the same molecule, 1, 3, 7 – trimethylxanthine, which causes a well-proven psychostimulant effect and can improve athletic performance.
At a weak dosage, several researchers have concluded, caffeine heightens attention levels, increases alertness and improves the performance of both simple and complex tasks. In 2005, a study of people who had consumed 75 or 150 milligrams of caffeine revealed improved reaction times, memory and information processing when compared with a control group. However, this study used only 48 subjects.
In any case, an adult should not consume more than 400 mg of caffeine per day, and a pregnant woman should not consume more than 300 mg daily, according to Health Canada. Research indicates that the toxic effects of caffeine can begin appearing at 1,000 mg. These include confusion, heart palpitations and even hallucinations.
Less Caffeine
But if coffee and tea both contain caffeine, why does tea have a reputation for being less stimulating?
First of all, a portion of coffee can easily contain twice the caffeine of an equal portion of tea. A cup of 250 ml of brewed coffee contains an average of 100 mg of caffeine, compared to 50 mg in the same portion of black tea. In an espresso, the quantity of caffeine can go up to 538 mg per 250 ml.
The leaves of a tea plant can contain more or less caffeine depending on the region where it is grown, the treatment to determine what kind of tea is produced (green, Oolong, black), and the form in which it is consumed (brewed or in a bag); but it will never equal the caffeine level of coffee.
Tannins Make the Difference
Tea is rich in tannins (also called thearubigins) that slow down the absorption of caffeine in the body. But tannins aren’t liberated immediately. As tea drinkers know, when tea leaves are plunged into boiling water they free up the caffeine they contain. It’s at this moment that tea is most “stimulant.” If the infusion lasts more than two minutes, it is then that the tannins are freed up, which lessens the stimulant effects of the caffeine in your body. In other words, your tea is stronger, more concentrated, but less exciting after two minutes in hot water.
An Energy Boost
Coffee and tea can boost your energy levels. The effect of coffee is almost immediate: your body absorbs 99% of its caffeine in 45 minutes, and it takes about five hours to eliminate half the caffeine ingested.
Tea offers a more progressive energy increase thanks to the L-theanine it contains. This acid has relaxing properties that counterbalance the stimulant effect of caffeine, while still keeping tea drinkers alert. Studies have shown that combining L-theanine and caffeine, as in tea, helps maintain alertness and concentration.
Verdict
Tea is a stimulant. But for people who suffer insomnia, feverishness and anxiety from consuming too much caffeine through coffee, they’re better off drinking tea. Tea contains half the caffeine and has tannins which diminish the stimulant effect.
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