In moderation caffeine can be a benefit—stimulating the metabolism, increasing brain function and alertness. However, the stress of modern life, and the prevalence of coffee and caffeinated colas, can lead people to caffeine overload.

The typical six-ounce cup of coffee contains 125-185 mg of caffeine, while there are about 45-60 mg in black tea, 15-20 mg in a cup of green tea, and 35-45 milligrams in a cup of white tea. (Note: caffeine levels can be significantly greater or lower than outlined here, depending upon the type of tea and how it is prepared.)

Because caffeine from tea does not take effect for 10-15 minutes, it provides more of a subtle lift, not the rapid jolt from a cup of coffee. The effect of caffeine is also complemented by another compound found only in tea, theophylline. While caffeine primarily is active in the brain and muscles, theophylline is active in stimulating the respiratory system, heart and kidneys. This corresponds to research that tea is helpful in maintaining a healthy cardiovascular system.