Back in the old days I wrote a post on Dobra Tea’s blog about caffeine. This is an updated version of that post.
The myth of green tea having less caffeine than black tea is rampant in our Western culture. This is even more surprising when contrasted with the attitude I found in Taiwan that drinking a fresh green tea late at night is much more likely to raise your energy level to the point of sleeplessness.
There is a very complex series of factors that go into the amount of caffeine in a cup. Soil, terroir, sunlight, leaf size, tippiness of a tea, age, roast, and infusion temperature all come in to play. Oxidation, though, is never really a factor. This means that all types of tea (green, white, yellow, oolong, black, and puer) have roughly the same amount of caffeine by weight.
That’s quite a bold statement when even the tea industry itself tends to print labels showing green tea as low in caffeine.
So how do we know what makes a cup of tea with higher or lower caffeine, because surely there are differences? There’s a few easy answers, and some more complicated ones.
Certainly a longer infusion time means a stronger tea. I suspect that the “green tea has less caffeine than black tea” myth has appeared because people often steep green tea for less time. There’s some great research in Tea: History, Terroirs, Varieties that shows the levels of caffeine in different styles of tea with the same steep time. It’s not surprising that they’re nearly all the same.
While infusing tea for a shorter time will decrease its caffeine levels, the quality of the leaf also matters greatly. A full-leaf, unbroken green tea is going to release its alkaloids much more slowly than a roughly-treated broken tea (such as you might find in a tea bag). There’s a lot more surface area on smaller leaf chunks in contact with water. As a result, broken leaves or even lower-quality “dust and fannings” will usually make a cup of tea that is blunt and bitter as well as much more caffeinated than its full-leaf brothers.
Finally (and I’m really just barely scratching the surface here), there are many other compounds within the tea leaf that contribute to how it affects the body. Tea leaves are one of the only sources of the amino acid Theanine which reduces stress on the body, making even many average 30mg-of-Caffeine cups of tea quite a different physical experience than the average 150mg-of-Caffeine cup of coffee. Looking at caffeine content alone is not sufficient to determine the physical effects of any beverage.
So the next time you’d like to decrease your caffeine intake, try a roasted oolong, an aged puer, or a tea with very few tips. Try to steep your favorite tea for much less time. Even better, as your body is unique, research and experiment with different teas and find what is true for you.