Q: How much
caffeine is in a cup of green tea?
A: An 8-oz. cup of green tea contains about 25-30 mg of caffeine. Black tea has about twice as much caffeine as green tea, weighing in at about 40mg, while drip coffee has a nerve-jangling 100-120mg. Although some people who are caffeine-sensitive may find that drinking green tea (especially in large amounts) keeps them awake at night, most people don't have this problem. That may be because green tea also contains theanine, a natural tranquilizer that counteracts the stimulating effects of caffeine.
Ever since 8th century Buddhist monks discovered that it could help them stay awake during marathon meditation sessions, tea has been used to increase energy, brighten the mood and refresh the mind. The invigorating effects of tea are due to caffeine, a central nervous system stimulant that fights sleepiness, speeds up the heart rate, increases alertness, improves athletic endurance, assists in weight loss and may even heighten intellectual activity.
Of course, the downside of caffeine is that too much can make you nervous, irritable, and unable to fall asleep at night. It can also reduce fine motor coordination and trigger headaches and dizziness. Most healthy adults can handle 200-250 mg. per day without adverse effects, but some find that even a small dose makes them jittery.The best of both worlds
When it comes to caffeine, green tea may offer the best of both worlds -- just enough to brighten the mood, but not enough to trigger sleepless nights. The average cup of green tea contains about 20 mg of caffeine, while black tea has about 40 mg, and drip coffee packs a nerve-jangling punch of 90-150 mg. Although some who are sensitive to caffeine may find that drinking green tea (especially in large amounts) keeps them awake at night, most people don't have this problem. That may be because green tea also contains theanine, an amino acid that functions as a natural tranquilizer.Decaffeinated tea For those who are really serious about limiting their caffeine, there is always the option of drinking decaffeinated tea. But beware, as the standard way of decaffeinating tea (using ethyl acetate) obliterates about 70 percent of green tea’s catechins. This method involves soaking the tea leaves in a chemical solvent called ethyl acetate, which binds to the caffeine. Then both the ethyl acetate and the caffeine are boiled away. Unfortunately, most of the health-promoting catechins also disappear in the process.
The carbon dioxide method (also referred to as "effervescence") is a much gentler, more natural process. The tea leaves are soaked in liquefied carbon dioxide gas, which binds to the caffeine and "soaks it out" of the leaves. The liquid and the caffeine are then poured off (no heating required), leaving about 95 percent of the tea catechins intact.
So if you do decide to drink decaffeinated green tea, be sure to look for a brand that uses the carbon dioxide or effervescence method. Otherwise, you may be drinking a brew that’s essentially devoid of catechins.
BBC News....Can green tea prevent or ease Alzheimer's disease, that devastating disease that can rob you of your ability to learn, reason, communicate, remember and carry out daily activities? Well, no one's saying that yet. But recent studies of the effects of green tea's catechins on animal brains are intriguing:
