Encyclopedia of Tea

TEA AND CAFFEINE

Q - How much caffeine is there in tea?
A - "According to the Food & Drug Administration of the United States, 'a serving of tea (about 5.5 oz.) generally contains about 40 milligrams of caffeine (less than half as much caffeine as in coffee), but the actual levels vary depending on the specific blend and the strength of the brew."

Q - Is there a difference in the caffeine content of Black, Green, Oolong and White Teas?
A - The difference in caffeine content in each type depends on the specific blend, temperature of the water and steeping time. It is a generally held view in the tea industry that black tea contains the most caffeine followed in descending order by oolong, green and white teas. The differences down the scale are subtle, though it is generally held that green tea contains about a third less caffeine than black tea, though some green teas may have the same or more caffeine that some black teas. It is for this reason that the FDA and the Tea Council set general levels for all teas.

Q - How much caffeine consumption is safe?
A - Despite recent publicity about caffeine, the fact remains that the consumption of caffeine at intakes of 300mg/ day has no adverse effects in the vast majority of the adult population. For this reason an average intake of three to four cups of teas a day is well within the level considered safe.

From "All About Tea" by William H. Ukers: The amount of stimulation which a person may be expected to get from a cup of tea cannot be stated. It depends upon the condition of (one's) nervous system, the strength of the decoction, and the nature and freshness of the leaves which (are) employed. When drunken in its weak state, in small quantities, tea is little more than a thirst quencher and an agent to increase perspiration. But when taken strong and continuously through the day, the aggregate gives a considerable stimulus to the system.