E-Health Guide
Cadence Health 2009
Caffeine, our favourite legal
drug
Caffeine-containing beverages, such as coffee and tea, are
drunk by millions around the world, making caffeine the
world's most popular psychoactive drug. But, do we have
need for concern over the ever-increasing array of caffeine
containing drinks?
Leanne Cooper looks at caffeine, its sources and its affect on
the body.
CAFFEINE FACTS
Caffeine is found in the leaves and beans of the coffee tree,
in tea leaves, guarana berries, and in small quantities in
cocoa and the kola nut. If you are a Rooibus tea drinker you
will be pleased to learn that this tea comes from a different
plant and contains no caffeine. Caffeine can also turn up
as an ingredient in cold medications, appetite suppressants,
and pain relievers and can be helpful against some
headaches and of course drowsiness.
Surprisingly, it's the leaves of the tea plant that contain the
most caffeine, around 5% compared to 1 -2% for coffee
beans2. The plant world uses caffeine cleverly for survival as
it helps to repel many insects.
A 375 ml cola drink contains around 40 mg of caffeine while a
250 ml energy drink contains around 80 to100 mg caffeine –
about the same as a shot of espresso1.
The rate at which caffeine is metabolized by our bodies
depends on our liver and its ability to deal with such drugs.
While women have been found to have more substances in
the liver that can clear drugs like caffeine faster than men, this
is influenced by hormone levels and medications. It takes
longer for women to clear drugs like caffeine when they are
pregnant or on the oral contraceptive pill.
Caffeine is rapidly absorbed in less than an hour. After this,
caffeine has a half-life (the time it takes for the total amount
taken in to be reduced or cleared to half the original total) of
3 ½ hours to 6 hours2.
As most of us know, caffeine is a stimulant to our central
nervous system (CNS), helping to keep us alert and
overcome feelings of drowsiness.
WHAT’S IN A CUPPA?
Depending on what you read the amount of caffeine any in
food will vary. The caffeine content of an average 150 ml
cup of tea varies from 30 - 100 mg, depending on how long
the tea is made. If you use milk, sugar, loose leaves or tea
bags (strong loose-leaf tea provides the most caffeine) all
create a different end result.
Coffee beans come in two flavours, Robusta, which has
more caffeine and Arabica. A 150 ml cup of drip-percolated
coffee has a typical caffeine content of 100 to 150 mg;
instant coffee has 60–100mg per 150 ml, depending on the
brand. An espresso comes in at around 90 mg per 150 ml1.
Consuming a whole 200 g block of chocolate, would mean
you would get the equivalent of about 550 mg of combined
methylxathines (caffeine and other stimulants). A 30 g bar
has between 20 to 60 mg caffeine1. This may be something
worth noting if you have a child that is overly active and
enjoys the odd bar of chocolate.
Given it’s our teenagers who consume the greatest quantity
of soft drinks; caffeine intake is something worth keeping an
eye on.
Note: Caffeine content is highly unpredictable in coffee
and tea drinks, especially in tea. Preparation has a huge
impact on tea, and colour is a very poor indicator of
caffeine content. Teas like the green Japanese Gyokuro
contain far more caffeine than much darker teas like
Lapsang Souchong, which has very little. Even
approximate caffeine contents assigned to teas are
generally at best a very inaccurate guess2.
WHAT EFFECT DOES CAFFEINE HAVE?
Drunk in moderation, caffeine for most of us is harmless and
can even have benefits. Just keep an eye on your intake and
children’s – whether is green tea or chocolate.
As we know caffeine is a central nervous system stimulant, it is
also a diuretic (increased the loss of fluid through the kidneys)
and affects our body in a number of ways.
Short-term effects include:

Contraction of the muscles, which can cause twitching.

An increased heart rate.

Slowing of blood flow to the stomach.

More sugar is released from the liver into the bloodstream.

Breathing tubes open up.

As an antioxidant, it may help prevent heart disease and
some cancers. Coffee also contains flavonoids, which are
also antioxidants.
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

Assisting premature babies experiencing breathing
difficulties. Minute amounts of caffeine given
intravenously can stimulate a newborn baby's brain to
tell the lungs to inflate.
Shift workers or others suffering from fatigue in their jobs
may benefit from caffeine's properties as a stimulant.
If you have a cup of coffee before bed you might find it
harder to sleep. You'll also find that you experience
deep sleep for shorter periods and have shorter dream
periods, so that you feel less rested when you wake up.
Though some tolerance to caffeine can lessen these
effects.


HAVE A COFFEE AND SOBER UP?
No chance, not even a strong cuppa can sober you up after
a few drinks. While caffeine will make you feel more alert it
will not alter your blood alcohol level.
WITHDRAWAL
To date caffeine is not considered addictive, however it can
be habit-forming. As we develop a tolerance towards it, we
need more in order to produce the same sensations. So we
drink more to 'top up' our reserves.
Withdrawal symptoms (usually starting within 12-24 hours and
peaking at 48 hours and lasting for between 1 and 5 days)
occur because after a day or so without caffeine the brain
begins to struggle on its own.
Other symptoms may include nausea, fatigue, drowsiness,
anxiety, vomiting and irritability; in extreme cases symptoms
may include depression, inability to concentrate and
diminished motivation to initiate or to complete daily tasks at
home or at work.
HOW MUCH IS TOO MUCH?
As we know caffeine affects people differently according to
their body’s ability to deal with it. It is generally considered
that you should consume less than 600 mg per day – around
four cups of strong drip-percolated coffee, or five or six cups
of tea (less is recommended for pregnant or breastfeeding
women)1.
IS YOUR COFFEE MAKING YOU NERVOUS?
Those of you who are self-confessed coffee addicts may be
interested to learn that at high intake caffeine is clinically
associated with a number of psychological conditions.
The
Diagnostic and Statistical Manual of Mental Disorders, Fourth
Edition (DSM-IV) states: "The 4 caffeine-induced psychiatric
disorders include caffeine intoxication, caffeine-induced anxiety
disorder, caffeine-induced sleep disorder, and caffeine-related
disorder not otherwise specified (NOS)."
Excessive caffeine intake, also known as caffeine-ism may result
in panic disorders, anxiety, bipolar disorder, and schizophrenia, a
growing number of medical professionals believe caffeineintoxicated
people
are
routinely
misdiagnosed
and
unnecessarily medicated.
PREGNANCY
Caffeine is quickly absorbed and reaches a peak
concentration in blood within an hour of ingestion: it also has
negative impacts on the unborn child. Studies have shown
that women who drink in excess of one cup of coffee a day
are only half as likely to conceive as those who drink less than
a cup a day. The odds are even worse for women who drink
more than two and a half cups a day (they are nearly five
times less likely to conceive as women who do not drink
coffee at all) (Wisborg, 2003).
Studies also suggest that caffeine reduces fertility in men by
damaging the sperm.
Caffeine has been reported to
negatively influence the production of hormones that control
fertility, for example it may reduce the rate by which an egg
successfully implants in the uterus1.
Unfortunately we don’t fully understand the impact caffeine
has on human development. We do know that as little as two
or three cups of brewed coffee every day during pregnancy
can result in lowered infant birth weight, prematurity, poor
reflexes and slowed neuromuscular development. There is a
far clearer picture of the effect of caffeine on infants and
children.
BREASTFEEDING
While the actual amount that a mother consumes – and
which then turns up in breastmilk - is variable, it is estimated
that 0.06% to 1.5% of the amount ingested actually crosses
into breastmilk. The half-life of caffeine is between 3 – 7 hours
(women not on the pill will be at the longer end). However for
newborns - who metabolise caffeine very slowly - the half-life
is 80 hours.
Interestingly though, caffeine has a therapeutic effect in
premature and near-miss SIDS infants. Caffeine’s minor effect
on respiration (increasing blood flow through the lungs and
increasing the supply of air) appears to be useful in treating
breathing problems of some prematurely born infants.
Caffeine has an affinity with the fatty, creamy layer of
breastmilk and consequently tends to be most concentrated
two hours after being ingested. In nursing mothers it appears
that caffeine can reduce milk supply and may be implicated
in recurrent mastitis (ABA, 2004). There are also some findings
that point to lowered iron levels in breastmilk of mothers who
drink caffeinated beverages – this may explain the increased
prevalence of iron deficiency anaemia in countries where
coffee is consumed in high levels.
Infants of mothers
consuming large amounts of caffeine can show signs of
agitation, jitteriness, constipation and general unsettledness.
A nursing mother need not deny herself the small pleasures in
life such as the occasional tea or coffee, she should however
be advised to keep her intake to one or two cups once in a
while, ideally after feeding.
The American Academy of Paediatrics suggests that nursing
mothers consume no more than three cups of coffee a day
(that is equivalent to less than 300mg/day); they also warn
that smoking increases the effect of caffeine in the body, so
mothers who smoke should reduce this amount even further.
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 www.cadencehealth.com.au
ATHLETES
Caffeine is a common aid in sport and hence why specific
levels of caffeine derivatives in the urine were once banned
in many sports. However, recently the ban was lifted.
But
remember there is a fine line between the benefit and cost
of caffeine use in sports, for example, intake of 13 mg/kg
and over greatly increases the risk of serious side effects
including gastric distress, anxiety attacks, heart palpitations
and headaches.
The use of caffeine in sport varies according to intensity of
the activity and the athlete’s body weight.
One last major variable must be considered and that is the
individuals ‘tolerance’ to caffeine, for example, habitual
coffee drinks may require a period of abstinence from
caffeine in order to gain beneficial effects from caffeine.
Caffeine’s effect on performance
Caffeine at intermediate dose levels of 5-mg/kg caffeine up
to three to four hours before intensive exercise stimulates the
oxidation of free fatty acids, as a glycogen sparing effect
researchers suggest that this is limited only to the first 15
minutes of activity (Burke, 1998). Other effects include
increased blood flow to the central nervous system and
consequently stimulation of the nervous system providing a
feeling of alertness and acuity.
Increased release of
adrenaline occurs at this dose also, stimulating muscle,
improving performance and generally causing an excitatory
effect on the nervous system.
Caffeine was once considered a diuretic, which was
believed to increase dehydration. However, we now know
that while caffeine does cause some fluid loss, where it is
consumed as a liquid there is generally a net gain in fluid.
Roughly 1.07 mg of fluid is lost from the body. Given most
drinks will provide about 200 mls of fluid this will still leave a
net gain of about 150 mls of fluid entering the body.
References:
1.
ABC online
2.
http://en.wikipedia.org/wiki/Caffeine
3.
Healthy eating for infants and children, the best start to life. L
Cooper, text book for the Certificate of Childhood Diet and Nutrition
4.
Cooper, Sports Nutrition and the Sporting Diet, text book for the
Certificate of Sports Nutrition
Cadence Health
Nutrition courses fresh to your door
 po box 313 manly nsw 1655 australia
 02 9400 9759
 [email protected]
 www.cadencehealth.com.au