Tea
And The Caffeine Myth
Author: Mark Weinstein
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.
