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					                                            CAFFEIN IN TEA

Caffeine is a naturally occurring chemical compound that can be found in 60 plants from around the
world. The best-known of these plants are camellia sinensis (the tea plant), coffee, yerba mate, cocoa,
and kola nut. It is often extracted from coffee and tea to produce "decaf" versions of the beverages. The
byproduct from this process, extracted caffeine, is used in most caffeinated sodas.

Caffeine is a stimulant that is quickly absorbed into the bloodstream and assimilated into the system. It
causes an increase in alertness and energy levels for a short period of time. Its chemical structure is
similar to adenosine, which triggers a decrease in cell activity, or a feeing of tiredness. It blocks the
brain’s adenosine receptors, tricking them into speeding up activity rather than slowing it down. (They
don’t recognize the caffeine itself, but react to the LACK of adenosine.) Also, where adenosine would
dilate blood vessels, caffeine causes them to constrict. When cell activity speeds up rapidly, the pituitary
gland interprets the neural firings as an emergency and releases epinephrine (a.k.a. adrenaline).
Adrenaline, in turn, increases your heart rate, blood pressure and blood sugar levels while dilating your
pupils and breathing tubes and tensing your muscles. The result? You feel excited, alert, and ready to go
. . . but not for long. Your body responds to the increase in blood sugar by releasing insulin. If your blood
sugar levels were rising rapidly (as they tend to do with the rapid absorption of caffeine), then the body
tends to overreact. It sends out too much insulin, resulting in LOWER blood sugar levels than BEFORE
you consumed the caffeine, as well as the craving for MORE caffeine.

Caffeine also alters the body’s response to dopamine, a neurotransmitter that activates the pleasure
centers in the brain, by increasing its content, then slowing its rate of up re-uptake. (That means you
feel happy at the time, but it’s harder to reproduce that feeling later without taking more and more
caffeine to get it.)

Together, these factors mean that caffeine is (according to Johns Hopkins University, anyway) addictive
and dangerous. Duke University has also published studies on its dangers to blood pressure and stress
levels.

For more information on the effects of caffeine, read How Stuff Works’ take on it and the University of
Texas’ blurb on caffeine and the brain, or watch this entertaining BBC video about caffeine and mental
performance (scroll to the bottom).
Caffeine in Tea: How It Works

So, it sounds like caffeine is a terrible thing and everyone should avoid it, right? Strangely enough, it is
widely reported that drinkers of tea experience a different effect than drinkers of other caffeine-
containing beverages. Tea drinkers describe an energy "plateau" that has a gradual increase, sustained
high, second energy boost, and gradual return to a "normal" energy level. Coffee and soda drinkers, on
the other hand, describe an energy "spike" and subsequent "crash" resulting in a lower energy level
than they originally had. Hippie talk? Maybe. Easily explained by the fact that coffee (usually) has more
caffeine than tea? Not really. Not enough research has been done for us to fully understand (or agree
on) why this is, but my thoughts on the matter are this: In freshly brewed tea, the caffeine binds to the
tannins (a.k.a. catechins, a type of polyphenol) and L-theanine when it is brewed. The bond requires
more time to metabolize than unbound caffeine, so the absorption of caffeine into the bloodstream is
slower and more gradual than it is with coffee and caffeinated sodas. (L-theanine also has some other
really cool benefits, like stimulating alpha wave production and GABA formation to induce an alert yet
euphoric state.) Meanwhile, the body is absorbing L-theophylline, a naturally occurring substance in tea
that produces similar effects to those of caffeine, but with a slower absorption rate. After absorption,
caffeine’s effects last about 4 hours, L-theophylline, about 8 hours, and the L-theanine, 8-10 hours. This
means that you are left with a calm, gentle return to your original energy level. Coffee is different from
tea in that its caffeine is quickly absorbed, causing an increase in adrenaline (and stress) levels and
resulting in a icky feeling when it wears off (often referred to as a "crash"). For more information about
the chemistry behind caffeine, read this article.



Caffeine Contents in Tea


Generally speaking, herbal teas have no caffeine, white tea has a little caffeine (about 15 mg per 8 oz),
green tea has more than white (20-40 mg), oolong has more than green (about 30) and black has the
most (40-70). (Coffee has about 80 mg per 8 oz., and we already know that those 80 mg may be
processed VERY differently from the caffeine in your tea.) There are many factors in a tea’s caffeine
content, so this is a very loose guide. The main stages to consider can be separated into three major
areas: growing, processing and brewing.

Growing

A number of factors involving the growing of your tea will influence its caffeine content. You must
consider the type of plant that is being grown and the growing conditions.

All true teas (white, yellow, green, red, oolong, black and puer) come from the same plant, camellia
sinensis. There are different varieties of this plant, each one with a different caffeine level. The more
prevalent Chinese variety (C. sinensis var. sinensis) contains the least caffeine (1-3% dry weight) and the
Indian Assam variety (C. sinensis var. assamica or C. assamica) contains the most (3-5% dry weight). In
between the two is the unusual Cambodian variety (C. sinensis var. parvifolia), which is considered to be
a hybrid between the other two varieties. The fact that the Assamica variety is most often used for black
tea helps to explain why black tea usually has more caffeine than the other teas. It is also worth noting
that Assam teas (usually grown in India, South America and Africa) are lower in the tannins that retard
the absorption of caffeine (see above).

Other "teas" (such as chamomile, lavender and rooibos) are actually tisanes, a.k.a. herbal teas.

Growing conditions also play a major role in determining caffeine content. A prime example of this is the
highly prized Japanese gyokuro green tea. Several weeks prior to harvesting, screens are placed over the
tea to block out the majority of the sunlight. The leaves are accustomed to more sunlight and increase
their chlorophyll content significantly to offset the imbalance they are experiencing. The increase in
chlorophyll then alters the levels of the plant’s sugars, amino acids and, of course caffeine. Other
environmental factors that may influence caffeine are rainfall, mineral content in the soil and water,
temperature and exposure to the sun (in terms of time and intensity).



Processing

The part of the plant that is being harvested makes a difference, too. Very young leaves are higher in
caffeine than older growths on the plant. In dry weight, the bud and the two leaves closest to it contain
about 5% caffeine, compared to 3.5% in the next set of leaves, 2.5% in the upper stem, and 1.4% in the
lower stem. Since white tea is usually picked from the youngest leaves, some white teas may be higher
in caffeine than some green teas.

Many also say that broken tea leaves (the kind most often used in tea bags) release more caffeine than
their whole leaf counterparts. It’s not that, per se. It’s really that broken tealeaves have an increased
surface area, which causes them to lose flavor rapidly. Tea baggers compensate by using more leaves
per serving, thus increasing the caffeine content.



Brewing

This is the factor you can control the most. Your brewing conditions can cause the same tealeaves to
release more or less caffeine. Higher heat, longer brew times, more leaves and less water will all
increase your caffeine content. The opposite conditions will decrease your brewed tea’s caffeine levels.
Earlier infusions have significantly higher caffeine contents than later ones. You can use this fact to
decaffeinate your tea.



Caffeine-Free vs. Decaf
Although people commonly use "caffeine-free" and "decaf" as synonyms, they are NOT the same thing.
Likewise, there’s a difference between something that is "caffeinated" and something that "naturally
contains caffeine."

"Caffeine-free" means the product does not contain any plants that naturally contain caffeine and no
caffeine has been added to it. It never had any caffeine in it before and it does not now.

"Decaf" means that most, but not all of the tea’s caffeine has removed. In many countries, there are
legal limits on the remaining caffeine content in "decaf" products, though there has been some
controversy over whether or not these laws are adhered to, particularly with regard to instant (bagged)
tea. (Bagged teas usually contain broken leaves and tea dust, which release more caffeine than whole
leaves. In other words, if you have a teaspoon of broken leaf tea and a teaspoon of whole leaf tea with
the same caffeine content, they will brew cups of tea with different caffeine content.)

So, if you’re fine with a little caffeine, decaf is OK for you. If you want a truly caffeine-free tea, stick with
tisanes (herbal teas).



Making Decaf


It is possible to reduce your tea’s caffeine content by about 80% on your own. Just warm an extra cup of
water to your brewing temperature or slightly higher, then brew the leaves for 1 minute. Pour out the
water, and then start brewing all over again with fresh hot water. Most of the caffeine is removed in the
first minute, so your brew will get only part of the remainder. A small amount (about 5%) of the
essential oils and polyphenols are removed, but if you don’t want the caffeine, it’s probably worth it.

Likewise, later infusions have significantly lower caffeine content than earlier ones. If you are serving a
tea that can yield multiple infusions (most can), give the first infusion to those who want more caffeine
and the later ones to those who prefer less. Most Chinese teas are considered to be at their best (taste-
wise) between the second and fifth infusions. Just be sure to brew the tea a little longer with each
successive infusion!



Tisanes (Herbal Teas)


Tisanes, commonly known in the U.S. as herbal teas, encompass a wide range of types and parts of
plants. Common tisanes include chamomile, peppermint, verveine, lavender, ginger and rooibos. There
are 60 caffeine-containing plants in the world. All tisanes are naturally caffeine-free unless they contain
one of those 60 plants. The most common of these plants, as they relate to tisanes, are yerba mate
(which may be blended with other tisanes or served on its own) and cocoa (which is sometimes used to
flavor teas and tisanes).
Recent Technological Innovations in Caffeine


Here’s an abstract for a new (and improved!) caffeine extraction method for tea. Here’s Wired
Magazine’s blurb on Japanese scientists’ isolation of the caffeine synthase gene, which is what causes
caffeine production in coffee, tea and the other 58 plants that naturally contain caffeine. They think it
can be suppressed to make naturally caffeine-free coffee and tea with the full flavor associated with the
real thing. Cool!

				
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