Tea appears to increase the activity of several infection-fighting white blood cells including B and T lymphocytes, and natural killer cells. When consumed along with large, fat-rich meals, it reduces the accumulation of fat in the blood and on sites of the body. John Weisburger, Ph.D., of the American Health Foundation recommends drinking 4 to 5 cups per day. Drinking more than four cups per day may substitute for up to two of the five to nine servings of vegetables and fruits recommended for health each day. Caffeine in Green Tea Green tea contains about 40 milligrams caffeine per cup, about half that of coffee.
Black teas have slightly more than green.
The small amount of caffeine in a cup or two of green tea is an amount and of a form which can help clear the mind and promote alertness. Too much tea, of course, and you wind up over-stimulated, as is the case with too much coffee. Because there is less caffeine in green tea than in coffee, however, and because it is in a form more slowly assimilated by the body, green tea provides a slower release of energy than the abrupt jolt one often gets from drinking coffee. You can decaffeinate your tea by pouring off the water after steeping the leaves or bag a minute or so, then re-adding hot water. Caffeine is released in the first one to two minutes of steeping.