Tea And The Caffeine Myth

While in Chicago for a long weekend trip, I visited several tea shops - it was nice to see that loose leaf teas are gaining in popularity at least in some parts of the U.S. There's definitely a lot yet to be done in terms of general education about the quality of different leaves - I will write another article about this, hopefully I'll have some physical samples soon. I came back with what feels like countless new things to write about, but for the moment let's just dispell the various rumors about caffeine in tea. We'll take a look at caffeine contents of different parts of the tea bush, absorption, flavor, and differences of caffeine in tea and coffee.

Let's start with some basic facts, from the beginning...: the quantity of caffeine in dry loose leaf tea is higher than the quantity of caffeine in the same weight of dry coffee beans. The caffeine content of a cup of tea, on average, is lower though (by about half), than the same in a like size cup of coffee. This is due to the fact that more tea is produced from the same amount of tea leaves than from coffee beans. Infusing tea beyond the recommended steeping time increases the caffeine content of the cup, which is something I recommend against - the flavor of the tea will be affected to some degree (the primary contributors to the tea 'flavor' is due to the interaction between the caffeine and polyphenols present in the leaves).

So, in short, a properly infused cup of tea generally yields about half the caffeine content of a cup of tea.

Caffeine content of a tea bush varies by the part of the bush used for your loose leaf tea. While caffeine levels vary slightly by region, the general breakdown of caffeine content is as follows:

Bud 4.50 %
First leaf 4.10 %
Second Leaf 3.40 %
Third Leaf 2.90 %
Upper stem 2.50 %
Lower stem 1.40 %

Depending on the type of tea you are drinking (white tea, for instance is primarily just buds, with high caffeine content). Many low quality loose leaf teas have higher net quantities of stems, resulting in a lower caffeine content tea. This is important, remember, because flavor is a matter of the essential interaction between polyphenols and caffeine in tea). As far as daily consumption is concerned, it is generally safe (and has no known - at least from what I've found in all my research) to consume as much as 10 to 12 cups of tea per day. I do have to add a word of caution here though.... tea is a diuretic, due to its caffeine content. You will need to drink more water to make up for fluid loss caused by drinking a lot of tea. I realize it may sound odd, but just try it! Drink a pot of real loose leaf tea, and you'll find yourself feeling dehydrated an hour later. Of course the same isn't true for the junk that passes itself off as tea (think Lipton ice tea, for instance).

To further illustrate the relative caffeine content in various beverages, here's a comparison:

Bottle of Coke (300ml) - 40mg caffeine (average)
Dark Chocolate Bar (50g) - 35mg caffeine (avg)
Cup of Coffee (8oz) - 100mg (avg)
Cup of Tea (8oz) - 35mg (avg)
A pharmacologically active dose of caffeine is 200mg and a fatal dose is 10,000mg. Important to note here is also that several studies suggest that as much as 70-80% of caffeine content consumed is actually not absorbed by the body.

Here is another one for you: caffeine content of green tea is approximately the same as it is in black tea. The fermentation process critical to the state of the final leaf (green or black) does affect the active Catechin (antioxidant) content of the leaf, but the caffeine content remains largely the same. So.... when the store clerk tells you that the green tea has less caffeine, don't take their word for it. Just stick with the recommended water temperatures and infusing times, and you'll get a great cup of tea - with a caffeine dose half that of coffee, and not detrimental to your health (standard disclaimer applies here, if you have any health concerns please do consult with your doctor).

On to the subject of decaffeinated tea: This probably warrants its own subject, but let's at least have this for a bit of reference. There are three commercial means of extracting caffeine from loose leaf tea, including the use of solvents (either ethyl acetate or methylene chloride) or the use of carbon dioxide. While producers insist that this affects the leaf only minimally, you will be drinking a tea with less than 0.4% caffeine (that's the max content of caffeine in the dry leaf for decaffeinated tea). Again here as a purist I do want to mention that the flavor interactions will be affected, and you are consuming a product altered through the use of foreign chemical substances. Buyer beware.