We recently wrote about the caffeine in tea, specifically looking into claims that caffeine in tea was somehow different than caffeine found in coffee, soda, or other products. We found that the jury was still out on the topic, with some studies showing that the combination of L-theanine and caffeine was less jolting. However, these studies used much greater quantities of L-theanine than is normally found in tea. This brings us to the next topic around how much caffeine is in tea. A search of web pages reveals a wide variety of information with many charts showing black tea as having the most caffeine followed by oolong, green, and white in descending order. We went searching to learn more about what things impact the amount of caffeine in tea and what ends up in your cup.
The Role of Caffeine in Tea
First lets set the stage a bit. Caffeine is found in true tea from the camellia sinensis plant. It is not found in herbals and tisanes like products featuring rooibos, honeybush, or other herbs. Many plants including both coffee and tea naturally produce caffeine as a way to protect themselves. Caffeine, like other compounds including nicotine and morphine, is a bitter tasting alkeloid, a feature which helps ward off many insects that would otherwise feast on plant leaves. It also tends to inhibit the growth of fungus thereby further protecting the plant. (Freeman and Beattie)
Recent research also suggests that there may also be another reason for caffeine in plants; to attract honeybees. Specifically, researchers have suggested that in low doses, having caffeine in pollen helps honeybees better identify the scent of a given flower providing a bit of reproductive advantage. (Wright, Baker, et all).
Caffeine and Types of Tea
Understanding that the presence of caffeine in tea is a self defense mechanism and that new growth is most vulnerable to insect attack, it should come as no surprise that the most desired part of the tea plant also has the highest caffeine. Specifically the bud and newest leaves, which are highly regarded for many types of tea, provide more caffeine than older growth. However, this isn’t the end of the story. The tea plant, c. Sinensis has evolved naturally over time into many varieties to suit the area in which they are grown. The sinensis and assamica varieties are the most notable but not the only varieties. Additionally, many countries including Japan, China, India, and Kenya actively work on producing specialized clones more suited to specific growing conditions, desired tastes, and leaf appearance. Each variety of plant differs in the amount of caffeine it produces and even the specific season of growth and available nutrients all impact caffeine production.
All types of tea, including green, black, white, and oolong, come from the same plant. The drying, rolling, and oxidization to achieve finished product does vary from type to type but the varieties still come from the same basic plant. Nothing in the standard production process extracts or otherwise removes caffeine from the leaves.
So what does this mean? Unless producers and retailers are sampling large volumes of leaf, for each and every product they offer, its really impossible to make specific claims about the amount of caffeine in any type of tea. It will fluctuate wildly within a very wide range; white, black, green, or otherwise. One might be able to avoid high amounts of caffeine by avoiding teas that are all tips but even this is no guarantee.
An alternative for many is to look for decaffeinated tea which theoretically allows enjoyment of tea without the caffeine. There are two general methods used in the decaffeination process of tea today; ethyl acetate (also known as “naturally decaffeinated”) and CO2. In the first case, ethyl acetate, which occurs naturally in the tea plant, is used to wash the tea leaves removing caffeine (as well as many other beneficial substances and flavor compounds) from the product. The washed tea leaves are then dried and repackaged. In the case of CO2, the leaves are also washed. This is done under more than 60 lbs of pressure per square inch (psi) at which point CO2 becomes a liquid. After washing the tea in liquid CO2 the leaves return to normal pressure at which point the remaining liquid CO2 simply evaporates. Both decaffeination processes are expensive, time consuming, and remove more than just the caffeine resulting in some compromise in taste and other compunds found in tea.
Aside from the impact on taste and other compounds, the process of decaffeination does remove most of the caffeine found in tea. If you live in the European Union and you buy decaf tea then you are in great shape. To meet EU standards a decaf product must have 99.9% of the caffeine removed. In the United States we aren’t quite as exacting, requiring only 97% removal. So if we assume that the amount of caffeine in any given tea sample may vary widely then so too might the amount of caffeine in your decaf tea.
Its worth noting that there is a myth floating about that you can eliminate most of the caffeine in tea by doing a quick initial steep, tossing the liquor, and re-steeping. Unfortunately the data under controlled conditions doesn’t support this myth at all. To eliminate the caffeine you would need to steep for 10-15 minutes, toss the liquor, and then steep again but who would want to drink that? For a much more in-depth look at caffeine and tea have a look at Caffeine and Tea: Myth and Reality by Nigel Melican which is one of the best reviews we have seen to date on the subject.
In summary, while the amount of caffeine in any given sample can be measured by a lab, as far as we can tell its really impossible to make sweeping claims about the amount of caffeine in any specific type of tea, much less one specific tea product. When we want to skip the caffeine we’ll have a a tisane or herbal tea.
Freeman, B.C. and G.A. Beattie. 2008. An Overview of Plant Defenses against Pathogens and Herbivores. The Plant Health Instructor. DOI: 10.1094/PHI-I-2008-0226-01, http://www.apsnet.org/edcenter/intropp/topics/Pages/OverviewOfPlantDiseases.aspx
G.A. Wright, D.D. Baker, M.J.Palmer, J.A. Mustard, E. F. Power, A. M Borland, P.C. Stevenson. Caffeine in floral nectar enhances a pollinator’s memory of reward. Science. Doi 10.1126. Science., http://www.ncl.ac.uk/press.office/press.release/item/bees-get-a-buzz-from-caffeine