Friedlieb F. Runge, a German chemist, first identified the compound caffeine in 1920, and named it kaffein from the German kaffee, meaning “coffee.” This naturally occurring substance is found parts of in many plants, wherein it acts as a natural insect repellant.
Caffeine is a natural, mild stimulant that has been classified by the FDA as safe for human consumption. It promotes general alertness as well as acting as a diuretic. This latter effect, however, is diminished in habitual tea and coffee drinkers, who seem resistant to the dehydrating effects. About 90% of Americans consume caffeine daily, usually through drinking coffee, tea, soda, or energy drinks.
Behind plain water, tea is the next most popular drink in the world, and has been on mankind’s menu for thousands of years. Some sources indicate tea has been around for 4700 years. Due to this long-lived popularity, it is not surprising that it is the largest source of caffeine consumption.
By raw weight, tea has more caffeine per ounce than coffee, but, due to customary brewing methods, a cup of tea generally contains less caffeine than a comparable serving of coffee. On average, five ounces of coffee contains about 80 mg of caffeine, compared with 45 mg in a 12-ounce can of soda, or 15-40 mg in a cup of tea, depending on the type.
It is sometimes misunderstood that white and green teas contain no caffeine. The fact is that since white, green, and black teas all come from the same species of plant, then they all must containe caffeine. It is the parts of the plant used and processing method that affects the amount of caffeine that makes it to the consumer.
The caffeine contents of various teas are determined by the variety of tea as well as its method of processing; generally, a serving of black tea has about 40 mg, while green tea has about 20 mg and white tea around 15.
However, the variation in caffeine levels is high in specialty loose leaf teas. These use different parts of the plant and wildly varying processing methods which can alter the caffeine content. And so it is difficult to know the caffeine content of these types of teas. For example, a spring Japanese green tea like Sencha can have more caffeine than a strong black tea like Lapsang Souchong, which is made from more mature tea leaves and is processed to a further degree.
Although some heavy coffee drinkers experience nervousness or jitters, many regular tea drinkers report instead a calming effect. Indeed, some studies suggest that moderate (less than 400 mg a day) caffeine intake has beneficial health effects. The polyphenols in tea, for example, are thought to have fat-burning qualities. As many beverages contain caffeine, one must moderate one’s intake to the recommended levels in order to enjoy the health benefits.
Of course, too much of one thing can have negative affects, and caffeine is no different. Besides the immediate and short term affects, other symptoms such as irritability, high heart rate, nausea, and insomnia can appear. Luckily, there are many decaffeinated versions of teas to try as a substitute. Additionally, herbal teas such as rooibos or chamomille are excellent substitutes and can even help calm and comfort a tea drinker prior to bed time.