You probably already know that tea contains caffeine, though generally much less than coffee. And you know that the caffeine in tea acts differently than any other sources because of the presence of the amino acid L-Theanine.
You might also be under the impression that black tea has the most caffeine while white and green tea have the least caffeine. This seems to be a commonly held (mis)belief: the caffeine content increases with the darkness of tea, more or less in this order: white, green, oolong, pu-erh, black.
I don’t know where that information originated or why that line of thought continues, so this next statement might just blow your mind:
That is no consistency across teas.
There is no standard. There is no way to predict caffeine levels in a given style of tea.
Sooo many factors affect the caffeine in a cup of tea. And laboratory tests done on various teas reflect this–white teas can be all across the board and oftentimes oolong and even black tea have lower levels of caffeine than the others.
How does the caffeine get into tea at all?
Caffeine is a naturally occurring compound formed in tea. It begins developing each year in the late winter and early spring when the plant struggles to grow up toward the sunlight. If the tea bush is shade grown (as many Japanese greens, including matcha are), it will continue it’s production of caffeine as it tries to absorb more sunlight.
Likewise, caffeine also acts a defense mechanism, protecting the plant from insects. Therefore, if bugs are particularly problematic or the leaves are picked later in a bug-filled season, the remaining tea leaves to be picked are likely to contain more caffeine.
Let’s dive into what affects the caffeine content in a cup.
Factors Affecting Caffeine
Growing Conditions and Picking Season
If the tea plant is grown in low light (shade or heavy mist) or is vulnerable to a lot of bugs, the caffeine level will be higher. Therefore, teas grown in foggy areas will tend to have more caffeine, as will some types of Japanese tea which are intentionally shade-grown, and some ancient Pu-erh’s in which the tender leaves are shaded by the older leaves on the big tea trees.
Picking season also affects the caffeine levels. Since white and green are picked earlier in the season, the caffeine that helped them reach the early spring sunlight is going to be very concentrated (and thus high). However, if a white tea is picked very early (before any bugs) in a sunny year, then it’s caffeine levels maybe quite minimal. Black tea, which tends to be picked later in the season, may have needed extra protection from bugs and therefore have higher levels of caffeine. Oolong tea, being neither the first picked, nor the last picked (typically) does not have the concentration of early caffeine in green and white, nor the bug protection caffeine of black. However, if the oolong (and this applies to pu-erh, too) is from a very misty mountain, the caffeine may be higher due to the need to seek sunlight.
Another less important growing factor is the amount of rain. The more rain, the more moisture the plant absorbs, the more the caffeine is diluted, particularly for leaves picked early in the season.
Parts Used and Processing Style
When we talk about tea, most of the time we’re talking about tea leaves. In the case of white tea, we usually think of leaves + bud. Since the caffeine is in the leaves and less so in the bud, by weight, white tea may have less caffeine that green. If you’re getting kukicha, or the leaf stems and twigs, there will be less caffeine because of fewer actual broad leafs.
The processing also affects caffeine: the more the leaves are broken, the easier it is for them to release their caffeine when infused with water. In this case, CTC black tea (typically found in tea bags) that has been largely cut or crushed will release a lot more caffeine that whole leaf black. This is also partly why matcha (powdered Japanese green) has sooo much caffeine: since the leaves have been powdered, there are infinite surfaces from which to release the caffeine.
Some preliminary evidence suggests that the fermentation and aging process of pu-erh reduces the caffeine content. This may partly explain why “ripened”/”cooked” and “aged” pu-erhs tend to have less caffeine than “raw.”
Generally speaking, the longer a tea steeps, the more caffeine it releases. This also contributes to black tea’s perceived higher levels of caffeine as it typically has the longest recommended steep time. In the case of matcha, since you’re eating the whole tea and none of the leaves are discarded, you will absorb all of the caffeine.
Each time a bunch of tea leaves is re-steeped, it will release additional caffeine, but each subsequent infusion will have less caffeine than the previous one.
Water temperature is paramount to how much caffeine is released, particularly in the case of white tea. You may have had the experience of drinking white tea after it’s been steeped in boiling water, only to realize that is a very caffeinated cup of tea! The hotter the water, the more caffeine that can be released. When steeped at the proper temperature, because of the hotter water, blacks and pu-erhs would have more liquefied caffeine. But with burnt greens and white (as is often the case in coffee shops), you may be drinking a LOT of caffeine.
Of course, the amount of actual tea infused will matter. Most bags of tea contain only 2 grams, while some have 3 or 4 grams. Tea-herb blends in bags, like for example Belight Tea, may be total of 3 grams, but only 1-1.5 grams of real tea, with the rest made up of caffeine-free herbs. Therefore the caffeine in a blend is going to be much less than the equivalent grams of pure tea. If you’re steeping loose leaf, the same principle applies: the more tea, the more possible caffeine exposure. You can reduce the caffeine yourself by mixing your tea with various caffeine-free herbs.
There are so many factors that affect caffeine content of tea, some of which you can control and some you can’t. If you’re trying to reduce the caffeine content in your beverage, opt for whole leaf tea (or kukicha), steeped at a lower temperature, for a shorter amount of time, and use less tea. Or just look for a decaffeinated tea (or caffeine-free herbal). Belight Tea is low to mild in caffeine because pu-erh is not one of the most caffeinated teas and it’s also been blended with caffeine-free herbs.
Keep this post as a reference and let’s stop perpetuating misinformation about caffeine levels in tea. The only way for you to know the true caffeine levels and how they affect you is by drinking a cup. And really, when you’re enjoying a cup of tea, are you worrying about the caffeine or just soaking in the fragrance and taste?
Leave a comment and tell us your experience with caffeine levels in teas. Which teas do you notice have the strongest caffeine effect for you? Which do you avoid drinking late in the day?