Steep time also affects the caffeine-content. If you've seen the claim about how chocolate is supposed to be good for. As far as the bottled beverages go, the average caffeine-content is very low, around 10mg per bottle. But to those that are sensitive to the stimulant, you still need to be aware that each 8 ounce cup contains between 10mg and 40mg of caffeine. But, the actual amount of green tea in those bottles is also very low.

The supplements contain the extracts, which provide the antioxidants known as catechins.

Catechins are unique to the callie sinensis plant (from which both black and green teas are derived) and some cocoa plants. Many companies add sugar, artificial flavors and colors. So, if what you want are the health benefits, without worrying about the caffeine in green tea, the best choice is a good supplement. They don't use much of the actual plant. Most companies give you an "average" content, if they list the content, at all. Longer steeps give you a richer flavor, but they also give you more of the stimulant. The caffeine in green tea is less than what you will find in an equal cup of coffee.

The variation has to do with the age of the leaves, when they are harvested from the plant and even their position on the plant.