WHAT IS THIS CAFFEINE DOING IN MY TEACUP The story of caffeine from the Camellia sinensis plant to y

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WHAT IS THIS CAFFEINE DOING IN MY TEACUP?
The story of caffeine from the Camellia
sinensis plant to you and me. World Tea
Expo March 2006 Las Vegas

• Paul Holmgren, PhD

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Caffeine is a natural and helpful complement in

• the lives of most Camellia sinensis plants.
• the balance of flavors in our teacups.
• the lives of most of us.
• We recognize that caffeine can be harmful in
  certain individuals especially when taken in
  large amounts.

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The Camellia sinensis Plant

• Synthesizes caffeine in order to protect itself
  against
• other plants (soil)
• insects
• microbes
• other threatening life forms

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Caffeine is molecularly similar to the adenine
our cells make.
adenine

• Adenine is used to make adenosine, which in turn
  is needed to
• Regulate (restrict) energy output by many body
  cells, especially nerve cells.
• make nucleic acid molecules such as DNA.

caffeine

• The three-dimensional shape of the caffeine
  molecule is similar to a key cell activity
  control molecule, adenosine, natural to all of us.

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Caffeine in the Tea Plant
5 4 3 2
Caffeine level indicated in red.
Percentages are gross approximations of caffeine
content dry weight.
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Caffeine in the Tea Plant Cell
Vacuole Containing Caffeine
Cell Wall
Cytoplasm
Caffeine indicated in red
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Caffeine During Withering
Caffeine
Cell Wall
Cytoplasm
Open Space
Caffeine indicated in red
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Caffeine Location in Manufactured Green (left)
and Black (right) Tea Cells
Cell Wall
Caffeine
Cytoplasmic Debris and Tea Polyphenols
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Live Tea Leaves
Note lack of granules on live leaf surfaces.
Complexed (combined) tea polyphenol and caffeine
molecules are located within the living cells you
see.
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Manufactured Green Tea
Note crusty thin layer of polyphenol/caffeine
granules on all leaf surfaces ready to become
dissolved in brewing water.
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Manufactured Black Tea
Note crusty thick layer of polyphenol/caffeine
granules on all leaf surfaces ready to become
dissolved in brewing water.
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Manufactured Black Tea
Blue background is my failed attempt at tea art!
At Greater Magnification Note crusty thick layer
of polyphenol/caffeine granules on all leaf
surfaces ready to become dissolved in brewing
water.
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Microscopic View of Black Tea Leaf
Note how the torn end (upper left) has more of
the leafs internal structure available to
contribute polyphenols and caffeine to the
brewing water than the untorn end (lower right).
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Caffeine Steeping Into Brewing Water and Teacup
Diagram of green tea cell, highly magnified, as
it might appear in brewing water.
Diagram of black tea cell, highly magnified, as
it might appear in brewing water.
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Caffeine Is a Contributor to Natural Tea Flavors

• contributes a unique bitter, structured taste to
  tea.
• considered pleasant especially by caffeine-needy,
  regular tea drinkers.
• forms complexes with other tea compounds to shape
  a larger flavor profile.

Theaflavin
Theobromine
Flavan-3-ols
Caffeine
Catechins
Flavonol-Glycosides
Amino Acids
Diagram of how caffeine complexes with other tea
components in your teacup, increasing the
complexity of tea flavors . Note caffeines
affinity for healthful catechins.
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Caffeine is rapidly absorbed.

• Most of the caffeine is absorbed from the
  stomach.
• Caffeine appears in the bloodstream 5-10 minutes
  after drinking a cup of tea.
• Peak plasma concentration occurs usually in
  about 60-75 minutes after drinking a cup of tea.
• Tea caffeine appears to be absorbed more slowly
  into the bloodstream than coffee caffeine.

Stomach
Bloodstream
Caffeine
Caffeine
Caffeine
Caffeine
Caffeine
Caffeine
Caffeine
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Caffeine Blocks Adenosine Receptors on Brain
Neurons

• Adenosine (A) accumulates with increased neuron
  activity. It slows brain neuron activity by
  combining with adenosine receptors on the neuron
  cell surface. (but)
• Caffeine (C) deters adenosine activity by
  combining with and blocking brain neuron
  adenosine receptors. Caffeine works by helping
  prevent adenosine-induced fatigue in brain cells.

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Caffeine facilitates Nerve 1s ability to excite
Nerve 2.
Nerve 1
Nerve 1
Nerve 2
Nerve 2
Caffeine, in effect, signals floodgate opening to
increase neurotransmitter flow from one neuron to
another.
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Caffeine increases glutamic acid activity in our
brains. This, in turn, excites four key brain
parts.
CC

• Cerebral Cortex (CC)
• Hippocampus (HI)
• Cerebellum (Cll)
• Reticular Formation (RF)

CC
CC
Hi
Hi
CC
Cll
RF
RF
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Caffeine minimizes the effects of the
neurotransmitter GABA, our natural brain
tranquilizer.

• GABA (gamma-amynobutyric acid) slows brain
  activity.
• Note that the tranquilizer, benzodiazepine (e.g.
  Valium), works by enhancing GABA activity.
  Caffeine neutralizes benzodiaziapene.

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By increasing the activity of a primary brain
stimulator and inhibiting a primary brain
tranquilizer, caffeine exerts a domino-like
effect on the entire brain

• the flow of most neurotransmitters is increased.
• the flow of nerve information is increased.
• For example

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Norepinephrine activity is increased.

• Norepinephrine acts on the amygdala, a primary
  memory/emotion center.
• Note that tricyclic antidepressants such as
  imipramine (Tofranil) work, in part by increasing
  norepinephrine activity.

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Serotonin activity is increased.

• Serotonin acts on raphe nuclei which
• regulate pain perception.
• stimulate the cerebral cortex.
• mobilize stress hormones.
• stimulates the limbic system.
• Increased brain serotonin is often associated
  with well being and tranquility.
• The pharmaceutical fluoxetine (Prozac) and other
  selective serotonin re-uptake inhibitors help
  increase serotonin activity in the brain.

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Acetylcholine activity is increased

• Under the influence of caffeine the
• basal nucleus of Meynert increases its
  acetylcholine output to the cerebral cortex.
• interpeduncular nucleus increases its
  acetylcholine output to the hippocampus.
• Note that the basal nucleus of Meynert is
  diminished in senile dementia and Alzheimers
  disease with a subsequent deficiency of
  acetylcholine.

CC
CC
CC
Hi
Hi
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For most of us, caffeine acts upon our brains to

• promote the flow of neurotransmitters and
  therefore the flow of information from one part
  of the brain to another.
• elevate mood.
• facilitate our handling of stressful situations.
• ward off fatigue.
• promote alertness.
• BUT ONLY FOR A LIMITED TIME

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Caffeine Metabolism and Half-Life

• Although the kidneys remove some caffeine, most
  of it is broken down to metabolites by the liver
  and delivered to the kidneys in the form of uric
  acid (an antioxidant).
• Caffeine metabolites include theophylline (a
  bronchodilator) and theobromine (diuretic,
  cardiac stimulant and vasodilator). Remember
  that theobromine is abundant in chocolate.
• Caffeine half-life is the amount of time it takes
  for half of the caffeine in circulating blood to
  be taken out of the bloodstream and metabolized.
  Half-life varies widely in individuals but
  averages 4-6 hours in the adult.

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Some Questions Explored

• How do we decaffeinate tea?
• Does the decaffeination process destroy the
  health benefits of tea?
• What factors determine caffeine levels in our
  teacups?
• How does tea caffeine compare with other sources
  of caffeine?
• Can caffeine be unhealthy?
• Are there healthful attributes of caffeine?
• Can we become addicted to caffeine?

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How do we decaffeinate tea?
Liquid Carbon Dioxide and Caffeine
Liquid Carbon Dioxide

• Today, most of our teas are decaffeinated using
  the supercritical carbon dioxide method. Here,
  tea is placed into a chamber and liquid carbon
  dioxide pumped into the chamber. Caffeine
  dissolves in the carbon dioxide and exits the
  chamber when carbon dioxide is removed.

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Does the decaffeination process destroy the
health benefits of tea?
Catechins
Liquid Carbon Dioxide
Liquid Carbon Dioxide
Caffeine

• Only a small proportion of healthful compounds
  (e.g., catechins) are removed from the tea leaves
  when the supercritical carbon dioxide
  decaffeination process is employed.

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What factors determine caffeine levels in our
teacups?

• Camellia sinensis variety (e.g., subspecies,
  jot).
• Growing conditions (e.g. soil nitrogen level).
• Manufacturing conditions (e.g., withering and
  fermentation conditions).
• Breakdown of cell wall (e.g. during the
  manufacture of black tea).
• Brewing time.
• Brewing temperature.

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How does tea caffeine compare with other sources
of caffeine?
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Can caffeine be unhealthy? Yes, caffeine

• is not metabolized efficiently in pregnant
  women.
• is hardly metabolized at all in the developing
  embryo or fetus.
• can interfere with normal sleep patterns.
• can promote ischemia in the brain.
• can cause cardiac irregularities.
• can promote apprehension and anxiety in some
  individuals.

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Are there healthful attributes of caffeine? Yes
some evidence suggests that caffeine

• users are less likely to be depressed than
  caffeine abstainers.
• works with tea catechins to help increase energy
  expenditure and weight loss.
• promotes insulin efficiency helping lower blood
  sugar.
• has antioxidant qualities (especially its
  breakdown product, uric acid).
• may have some anticancer qualities (but some
  cancer promoting qualities as well).

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Can we become addicted to caffeine?

• Not in the same way we can become addicted to
  many other drugs. However
• habitual caffeine users develop larger numbers
  of adenosine receptors on neurons and brain
  vasculature (upregulate) making adenosine work
  more efficiently when caffeine is absent. This
  may cause the depression and headache often
  associated with caffeine withdrawal. These
  symptoms typically go away in a few days,
  probably as the adenosine receptors adjust and
  become fewer in number (down regulate).

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Caffeine is a natural and helpful complement in

• the lives of most Camellia sinensis plants.
• the balance of flavors in our teacups.
• the lives of most of us.
• We recognize that caffeine can be harmful in
  certain individuals especially when taken in
  large amounts.

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QUESTION PERIOD
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