http://www.medicalnewstoday.com/articles/285194.php at 06.

15;November 17th 2014

What is caffeine?  Around 5 grams of caffeine can be fatal.

This is the equivalent of some 30-40 cups
How does caffeine of regular coffee.

work?  Some 50% of people who quit using

caffeine experience
severe headaches that typically last
between 2-9 days.
 The substance is derived from over 60
If your morning ritual consists of making
various types of plants around the world.
a grab for a takeout tea or coffee to get
 Energy drinks with high volumes of
your much-needed caffeine fix, you are
caffeine: Red Bull is the most popular
not alone. Caffeine is used by the
energy drink in the US with Monster a
masses on a daily basis to increase
close second.
wakefulness, alleviate fatigue, and
 Some 5% of adults consume 5-7 energy
improve concentration and focus.
drinks every month. Over 2% of adults
Caffeine is the most commonly used drug in consume at least 10 energy drinks every
the world. Although the consumption of low month.
to moderate doses of caffeine is generally
What is caffeine?
safe and has many proven health benefits,
caffeine is causing quite a stir as a potential In the US, more than 90% of adults use
source for certain health problems with caffeine regularly, with an average
continued use. consumption of more than 200 mg of
caffeine per day - more caffeine than in two
Fast facts on caffeine
6 ounce cups of coffee or five 12 ounce
Here are some key points about caffeine.
cans of soft drinks.
More detail and supporting information is in
the main article.18

 At least 68 million Americans drink three More than 90% of adults in the US use caffeine
cups of coffee every day. regularly with an average consumption 200 mg or
more per day.
 Some 30 million Americans drink five or
more cups of coffee every day. Caffeine is a bitter, white crystalline xanthine

 Over 21 million Americans drink six or alkaloid - a term used for substances
more cups of coffee every day. produced as end products of nitrogen
metabolism in some plants. The stimulant
 It is believed that some 3 out of 4 regular
chemical is also known as coffeine, theine,
caffeine users are "addicted" to the
substance. mateine, guaranine, or methyltheobromine. 14

 Consuming as little as 200 mg of caffeine Caffeine belongs to the family of

a day can lead to addiction and altered heterocyclic compounds known as purines
chemistry in the brain. and is a member of a group of naturally
http://www.medicalnewstoday.com/articles/285194.php at 06.15;November 17th 2014

occurring substances called The Food and Drug Administration (FDA)

methylxanthines. It has the systematic name says that caffeine is both a drug and a food
3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6- additive. Caffeine is used in both
dione, also known as 1,3,7- prescription and over-the-counter medicines
trimethylxanthine, and 1,3,7-trimethyl-2,6- to treat tiredness, drowsiness and to
dioxopurine. improve the effect of some pain relievers. 3

The chemical formula is C H N O . Caffeine

8 10 4 2
Coffees, teas and chocolate can all contain
has a molar mass of 194.19 grams (6.85 caffeine.
ounces). It is soluble in water and many
When purified, caffeine is an intensely bitter
organic solvents, has a melting point of 235-
white powder. It is added to enhance colas
238 °C and it appears in pure form as white
and other soft drinks so that they impart a
crystals. Caffeine can be prepared by
pleasing bitter note. However, caffeine is
extraction from natural sources or synthesis
also considered to be an addictive stimulant.
from uric acid.
In humans, caffeine stimulates the central
nervous system, heart rate, and respiration,
Where is caffeine found?
has psychotropic (mood-altering) properties
Caffeine occurs naturally in the leaves, and acts as a mild diuretic. 13

seeds or fruit of more than 60 plant species,

Sources of caffeine include:
including:
 Coffee and tea
 Coffee beans - seed
 Chocolate
 Tea leaves - leaves, bud
 Soda
 Kola nuts - seed
 Sports beverages
 Cacao beans - seed
 Energy drinks.
 Guarana - seed
Caffeine belongs to the group of medicines
 Yerba mate - leaf
called central nervous system (CNS)
 Yoco - bark. stimulants. In conventional foods, caffeine

Caffeine acts as a natural pesticide for the may help restore mental alertness when

plants, and paralyzes and kills insects that unusual tiredness, weakness or drowsiness

attempt to feed on the plants. The German occurs. Caffeine's use as an alertness aid

chemist Friedrich Ferdinand Runge first should only be occasional. It is not intended

isolated the molecule in 1819. 14 to replace sleep and should not regularly be

Man-made caffeine is sometimes added to used for this purpose. 12

foods, drinks, and medicines. 3

Sources of caffeine in dietary supplements
What is caffeine used for? include:
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 Capsules Caffeine is even being added to

 Tablets marshmallows, sunflower seeds and other

snacks for its stimulant effect. 4

 Powders
Caffeine content
 Energy shots
For healthy adults, the FDA has cited 400
 Energy drinks. milligrams of caffeine a day - about 4 or 5
Caffeine is also used in combination with cups of coffee a day - as an amount not
ergotamine, for the treatment associated with dangerous or negative side
of migraine and cluster headaches, or with effects.
certain pain relievers, such as aspirin and
The FDA has not set an amount for children,
acetaminophen. Caffeine helps to increase
but the American Academy of Pediatrics
the effectiveness of these medicines. 12

discourages the consumption of caffeine

Caffeine can also be used: and other stimulants by children and
adolescents. 4

 To treat breathing problems in premature

babies The amount of caffeine included in some
common foods and beverages are: 19

 For postoperative infant apnea -

breathing problems after surgery in young
For healthy adults, about 4 or 5 cups of coffee a day
babies
is an amount not associated with dangerous or
 For psychiatric disorders requiring negative side effects.
electroconvulsive or shock therapy
 Coffee, brewed - 40 to 180 milligrams
(ECT).
(mg) per cup
Caffeine no longer only features in tea,  Coffee, instant - 30 to 120 mg per cup
coffee and chocolate. Caffeine is regularly
 Coffee, decaffeinated - 3 to 5 mg per cup
added to gum, jelly beans, waffles, water
and syrup to name a few. 4  Tea, brewed American - 20 to 90 mg per
In response to the trend of "added caffeine" cup

in a growing number of products, the FDA is  Tea, brewed imported - 25 to 110 mg per
investigating the safety of caffeine in foods cup
and particularly its effects on children and
 Tea, instant - 28 mg per cup
adolescents. 4

 Tea, canned iced - 22 to 36 mg per 12

"Energy drinks" with caffeine are considered ounces
by some to be aggressively marketed,
 Caffeine-containing cola and other soft
particularly to young people, with additional
drinks - 36 to 90 mg per 12 ounces
products appearing on the market, from
"psyched up" oatmeal to "wired" waffles.  Cola and other soft drinks, decaffeinated
- 0 mg per 12 ounces
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 Cocoa - 4 mg per cup is also a diuretic; causing the body to lose

 Chocolate, milk - 3 to 6 mg per ounce more water - it is considered neither

beneficial for hydration nor thirst, although
 Chocolate, bittersweet - 25 mg per
some studies dispute this. 3

ounce.
How does caffeine work?
How does caffeine affect the
Following oral consumption, caffeine is
body?
absorbed into the blood and body tissues
Whether caffeine is consumed in food or as with absorption virtually complete in around
a medicine, it changes the way your brain 45 minutes after ingestion. The peak plasma
and body work and changes how you caffeine concentration is reached 15-120
behave and feel. minutes after ingestion.

Caffeine is a central nervous system Adenosine is a chemical that is present in all

stimulant. The central nervous system human cells. It readily combines with
includes the brain, spinal cord, and the other phosphate to form various chemical
nerves in the body. Caffeine's main effect on compounds, including adenosine
the body is an increased temporary sense of monophosphate and adenosine
wakefulness and alertness, but it can also triphosphate.
cause issues such as: 3

 Jitters and shakes

To a nerve cell, caffeine looks like adenosine.
 Impeding sleep
Caffeine uses all the receptors adenosine should
 Fast heart beat bind to and as a result, instead of slowing down
because of the adenosine level, the cells speedup.
 Uneven heart rhythm
In the brain, adenosine is an inhibitory
 High blood pressure
 Headaches neurotransmitter; it binds to adenosine
receptors in the brain. This means
 Nervousness
adenosine can act as a central nervous
 Dizziness system depressant.
 Dehydration
In normal conditions, adenosine promotes
 Dependency.
sleep and suppresses arousal by slowing
Once consumed, caffeine reaches peak down nerve activity. Adenosine binding also
level in the blood within one hour and causes blood vessels in the brain to dilate,
remains there for four to six hours. to increase oxygen intake during sleep.
When awake, the levels of adenosine in the
Caffeine increases the release of acid in
brain rise each hour.
your stomach, sometimes leading to
an upset stomach or "heartburn." Caffeine
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To a nerve cell, caffeine looks like Caffeine also increases levels of the
adenosine. Caffeine binds to the adenosine neurotransmitter dopamine. 14

receptors. However, in contrast to

Caffeine is quickly and completely removed
adenosine, it does not decrease the cell's
from the brain. Its effects are short lived, and
activity. As caffeine utilizes all the receptors
it tends not to affect concentration or higher
adenosine binds to, the cells can no longer
brain functions negatively. However,
sense adenosine. As a result, instead of
continued exposure to caffeine leads to the
slowing down because of the adenosine
development of a tolerance to it.
level, the cells speedup.
Smokers typically break down caffeine more
Caffeine blocks adenosine's ability to open
quickly than non-smokers, while pregnancy
up the brain's blood vessels, causing them
tends to slow down the rate at which
to constrict - this is the reason caffeine is
caffeine is broken down, particularly during
used in pain reliever medicine for
the later stages. Elimination of caffeine from
headaches. If the headache is vascular, the
the body is accomplished mainly through
caffeine closes down the blood vessels and
metabolism in the liver, hence liver diseases
gives relief.
might impact on the rate of caffeine
elimination. This may also happen in
With caffeine blocking adenosine, there is
individuals taking some medical treatments
an increase in the firing of neurons in the
that are metabolized by the liver.
brain. The pituitary gland observes the
increased activity and perceives it as an Caffeine side effects
emergency, so it releases hormones that tell
the adrenal glands to produce adrenaline Heavy daily caffeine use - more than 500 to

(epinephrine). Adrenaline is the "fight or 600 mg a day - may cause side effects such

flight" hormone and it has a number of as:6

 Insomnia
effects on your body:
 Nervousness
 Dilates pupils
 Restlessness
 Opens breathing tubes
 Irritability
 Increases heartbeat
 Stomach upset
 Constricts surface blood vessels,
 Diarrhea
increasing blood pressure
 Dizziness
 Slows blood flow to stomach
 Nausea
 Releases sugar from the liver into the
bloodstream for extra energy  Fast heartbeat

 Tightens muscles.  Muscle tremors.

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Most adults need seven to eight hours of dramatically increased and are often
sleep each night. Caffeine can interfere with marketed toward children and adolescents 2

the sleep cycle; it decreases the quantity of Although the FDA deems caffeine a "safe"
sleep and the temporal organization of slow substance, its potential adverse effects on
and REM sleep. Sleep loss is cumulative, children and adolescents are largely
and even small nightly decreases can add unknown. The FDA does not currently
up and disturb daytime alertness and regulate caffeine content in energy drinks
performance. 6
unlike that of cola because energy drinks
are marketed as and considered to be
The negative effects linked to
dietary supplements. 2

overconsumption are short lived once an

Approximately 73% of children consume
individual returns to their regular pattern of
caffeine on a given day and this proportion
consumption.
has not changed over time. Percentage of
Some medicines and herbal supplements consumers increased from 63% among
may interact with caffeine: 6
children aged 2-5 to ∼75% among older age
 Some antibiotics: ciprofloxacin and groups.2

norfloxacin - interfere with caffeine

Soda accounted for the majority of caffeine
breakdown
intake in 1999-2000 (62%), and tea was the
 Theophylline: a bronchodilator - caffeine
second largest contributor to overall caffeine
increases concentration of theophylline in
intake. Coffee accounted for only 10% of
blood
caffeine intake in 1999-2000 with an
 Echinacea: herbal supplement - increase to nearly 24% in 2009-2010.
increases caffeine concentration in blood.
Energy drinks represent nearly 6% of
Children and adolescents
caffeine intake in 2009-2010. 2

Physicians and policy makers are

Mean caffeine intake has not increased
increasingly interested in caffeine intake
among children and adolescents in recent
among children and adolescents in the
years. However, coffee and energy drinks
advent of increasing energy drink sales. 2

represent a greater proportion of caffeine

The majority of caffeine intake among
intake as soda intake has declined.
children and adolescents is due to soda and
tea consumption. Energy drinks, which Case reports of caffeine toxicity and deaths
provide a potent source of caffeine, have among adolescents and adults reflect the
increased in availability in the US in recent potential dangers of excess caffeine or
years. Specialty coffee drinks, and food energy drink consumption. 2

products containing caffeine such as candy A study of seventh, eighth, and ninth-grade
bars, potato chips, and gum have also students in Ohio found that students took in
an average of 53 mg of caffeine per day.
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Almost one in five students took in more  Sleepiness

than 100mg of caffeine each day. 3
 Lethargy
Caffeine tolerance
 Lack of concentration
If individuals use caffeine on a daily basis,
 Constipation
their bodies will no longer experience the
 Muscle aches
"good effects" of feeling more awake and
 Temporary feelings of depression
able to concentrate unless the dose is
 Flu-like symptoms
increased. This consequence is called
"tolerance." 3  Irritability

When the adenosine receptors are blocked  Insomnia.

with caffeine molecules, dopamine (the feel People often take more caffeine to make
good chemical) works more efficiently. The these symptoms "disappear," creating an
excess adenosine signals the adrenal ongoing cycle that is tough to break. 3

glands to release adrenaline, which further What is caffeine dependence and

perpetuates the feeling of alertness. withdrawal?
Over time, the brain adds more adenosine There has been much debate surrounding
receptors to compensate for the caffeine, the question of whether caffeine is an
which causes a "tolerance" to build up to the addictive substance and whether the
caffeine molecule. cessation of consumption will result in
withdrawal-like symptoms. 15

When a person misses or decides to quit

Caffeine does fit the definition of habituation,
their usual caffeine dose, the brain is then
which in simple terms means to consume
flooded with adenosine, and dopamine
something in a regular pattern. Habituation
levels drop drastically causing the brain's
and addiction are very different. In addition,
chemistry to be out of balance.
a substance has to fulfill 4 out of 7 different
The increased adenosine plus a drop in criteria to be considered a drug of
adrenaline levels leads to caffeine dependence, according to the American
withdrawal symptoms. 15
Psychiatric Association (APA).
Some studies show that caffeine causes a
In 2013, the APA added caffeine withdrawal
physical dependence or addiction. If a
to the list of recognized conditions in the
person experiences withdrawal symptoms
Diagnostic and Statistical Manual of Mental
when they suddenly stop using caffeine then
Disorders (DSM-V). Only a subset of the
the person has a physical dependence on
population of caffeine consumers suffers
caffeine.3

withdrawal symptoms. Symptoms begin

Withdrawal symptoms can be unpleasant
about 12-24 hours after sudden cessation of
and include: 15

 Severe headaches caffeine consumption and reach a peak after

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20-48 hours. A gradual reduction in  Calorie burning: caffeine may stimulate

consumption over a period of days does not thermogenesis - one method your body
uses to generate heat and energy from
result in these symptoms.
digesting food.
Research has shown that caffeine does not
activate the pathways in the brain that are Alertness
related to addiction and reward in opposition
to "hard" drugs. Therefore, researchers The European Food Safety Authority (EFSA)
conclude that caffeine is not an addictive concluded that a cause and effect
substance. relationship has been established between a
75 mg serving of caffeine and both
Brain mapping technology indicates that
increased attention and alertness.
caffeine is not linked to the brain circuit of
dependence. This is supported by the fact Caffeine is said to be comparable to sleep
that individuals do not develop a tolerance to when a break is needed from driving to
the stimulant effects of caffeine. The recover alertness.
American Psychological Association also
Caffeine does not make a drunken
does not recognize caffeine as being an
person sober or fit to drive - it does not
addictive substance.
get rid of the effects of alcohol.
Does caffeine have any health
benefits? Sports performance
Studies have shown caffeine to have
Caffeine is known to have ergogenic
potential health benefits; some of these are
benefits and can improve physical
discussed below.
performance during endurance exercise.

Caffeine can improve physical performance during The EFSA has recognized that a cause-and-
endurance exercise. effect relationship has been established for
caffeine intake and increased endurance
performance, endurance capacity (in both
Weight loss
cases for 3 mg/kg body weight 1 hour

Caffeine may boost weight loss or prevent before exercise), and reduction in perceived

weight gain, although there is no conclusive exertion (4 mg/kg body weight 1 hour before

evidence to determine long-term results. exercise).

Possible theories of how caffeine might The effects of caffeine on short-term high-
affect weight include: intensity exercise remain inconclusive.

 Appetite suppression: caffeine may Caffeine mixed

reduce the desire to eat temporarily
with carbohydrates replenishes muscle
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glycogen concentrations faster after lifelong caffeine consumption and the risk of
exercise. developing Alzheimer's disease.
There is a wealth of epidemiological studies
Caffeine also relieves post-workout muscle
reporting an inverse association between
pain by up to 48%.
coffee consumption and risk ofParkinson's
disease. The relationship is dose-
Brain function
dependent and suggests a possible causal
effect. According to animal studies, it is likely
Caffeine acts at brain level by antagonizing
that caffeine in coffee is the main
the A1 and A adenosine receptors. When
2A

component responsible for the potential

caffeine is absorbed in the form of coffee,
preventative effect of coffee in Parkinson's
certain other constituents of coffee, such as
disease involving mainly its antagonism at
polyphenol antioxidants, act on various
A adenosine receptors.
2A

pathways and may play an additional

When caffeine is absorbed in coffee, the
protective role.
direct effects of caffeine on neuroprotection
seem to be reinforced by the effects of some
Cognitive decline other coffee constituents that together seem
to act on the brain vascular system, the
Several epidemiological studies suggest that
blood-brain barrier and inflammation.
a regular, lifelong, moderate consumption of
caffeine may slow down physiological, age-
related cognitive decline, especially in Memory
women and those over 80 years old.
Research from Johns Hopkins University
However, more studies are still needed to
suggests that a dose of caffeine after a
increase the statistical power for the
learning session may help to boost long-
detection of an association between caffeine
term memory. The team concluded that at
and cognitive impairment.
least 200 mg of caffeine is required to
observe enhancing effect of caffeine on
Alzheimer's and Parkinson's disease memory consolidation.

Caffeine decreases the risk for age-related

cognitive decline in diseases such as Liver and colon
Alzheimer's and Parkinson's.
Caffeine may detox the liver and cleanse the
Animal studies have shown that caffeine colon when taken as a caffeine enema.
may be able to counteract a variety of
According to a study published in the
pathologies related to Alzheimer's disease.
journal Hepatology, researchers have
A systematic review and meta-analysis
discovered that increased caffeine intake
found a trend toward a protective effect of
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may reduce the risk of non-alcoholic fatty in women, and a 10% lower risk in men,
liver disease. compared to drinking less than one cup per
month.

Eyelid spasm
Suicide
Caffeine may help protect people from an
eye disorder known as blepharospasm, The World Journal of Biological
according to a study published in the Journal Psychiatry published a study that concludes
of Neurology, Neurosurgery and Psychiatry. with an association between caffeine
The condition, caused by abnormal brain consumption and a lower risk of suicide. 22

function, makes people blink incessantly and

can leave them functionally blind. 20

Fertility

Cataracts Caffeine-consuming men showed an

increase in semen volume, movement and
Researchers from the University of Maryland significantly less sperm DNA fragmentation
School of Medicine in Baltimore, MD, found than non-caffeine-consuming men in a
that caffeine may be effective in protecting study.
the lens against damage that could lead to
the formation of cataracts.
Erectile dysfunction

Skin cancer A study by the University of Texas Medical

School in Houston stated that the total
A Rutgers study strengthens the theory that caffeine intake equivalent to about 2-3 cups
caffeine guards against certain skin of coffee (250-375 mg/day) is associated
cancers at molecular level by inhibiting a with a significantly lower reportage
protein enzyme in the skin, known as ATR. of erectile dysfunction. Reduced risk was
Scientists believe that based on what they even observed among men consuming as
have learned studying mice, caffeine applied little as 85 mg of caffeine daily. 23

directly to the skin might help prevent

damaging ultraviolet light from causing skin
Tinnitus
cancer.
In another study, researchers at Brigham A prospective study published in The
and Women's Hospital, Harvard Medical American Journal of Medicine followed a
School in Boston, MA, and Harvard School group of 65,085 nurses since 1991. Higher
of Public Health, found drinking three cups caffeine intake was associated with a lower
of caffeinated coffee was linked to a 21% risk of incident tinnitus in women. 24

lower risk of developing basal cell carcinoma

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Kidney stones that the participants who increased their

coffee intake by more than one cup a day
A study of 217,883 participants analyzed the (on average, an increase of 1.69 cups per
association between caffeine intake and the day) over a 4-year period had an type 2
risk of developing kidney stones in three diabetes risk 11% lower over the
large cohorts of US health professionals. 25

subsequent 4 years, compared with people

In all three cohorts, participants with higher who did not change their intake.
intakes of caffeine had a reduced risk of In addition, people who lowered their daily
developing kidney stones. Intake of caffeine consumption by more than one cup of coffee
from sources other than coffee was also (on average, a decrease of two cups per
associated with reduced risk of kidney day) showed a 17% higher risk for type
stones. 2 diabetes.

Further claimed health benefits of caffeine

Mouth and throat cancer include:

In a study of 968,432 men and women,  Decreased risk of endometrial cancer

 Reduced risk of prostate cancer
participants who reported drinking more than
 Protection against head and neck cancer
4 cups of coffee a day had a 49% lower risk
of death from oral cancer compared with  Helping to prevent the return of breast
those who reported not drinking coffee at all cancer.

or only an occasional cup.

What are the risks of consuming
caffeine?
Stroke Before racing to the kitchen and brewing
endless cups of tea and coffee to maximize
Data from Sweden, of 34,670 women on all the potential health benefits of
without a history of cardiovascular disease caffeine, below are some of the potential
in 1997, was examined finding women who risks of consuming caffeine.
drink more than one cup of coffee per day to
have a 22 to 25% lower risk of While much of the research published does

stroke compared with women who drink allude to the safety and even potential

less. They found that low or no coffee benefits of caffeine (in moderation), there

drinking was linked to an increased risk are a handful of research studies that

of stroke. highlight the potential harmful effects of

caffeine.

Type 2 diabetes
It is recommended that pregnant women consume
Analysis drawing data from three large less than 300 mg of caffeine a day.
studies, covering a 20-year period, found
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Depression 250 mg of caffeine - or the equivalent of 2 to

2 1/2 cups (473 to 591 milliliters) of plain,
There is no clear link between caffeine brewed coffee a day may cause this effect. 11

intake and depression. However, caffeine

intake and depression may be linked
Pregnancy
indirectly among people who are particularly
sensitive to the effects of caffeine or who
Studies in humans have shown that caffeine
have too much caffeine. 8

may cause miscarriage or may slow the

growth of a developing fetus when given in
Hypertension doses greater than 300 mg (an amount
equal to around three cups of coffee) a day.
Caffeine can cause a short but dramatic In addition, use of large amounts of caffeine
increase in your blood pressure. It is unclear by the mother during pregnancy may cause
what causes this spike in blood pressure. problems with the heart rhythm of the fetus. 13

Some researchers believe that caffeine

Caffeine can cross the placenta and affect
blocks a hormone that helps keep your
the baby's heart rate. While further research
arteries widened. Others think that caffeine
is needed, some studies suggest that
causes your adrenal glands to release more
drinking too much caffeine during pregnancy
adrenaline, causing blood pressure to
might be associated with an increased risk
increase.10

of miscarriage.
Caffeine has a stronger blood pressure
increasing effect in men who are older than It is recommended that pregnant women
70 or who are overweight. 10

consume less than 300 mg of caffeine a

When people with high blood pressure were day. Studies in animals have shown that
given 250mg of caffeine in a study (about caffeine causes birth defects when given in
two coffees), the data revealed that their very large doses (amounts equal to 12 to 24
blood pressure was elevated for about 2-3 cups of coffee a day) and problems with
hours. bone growth when given in smaller doses. 13

Blood sugar Breast-feeding

Caffeine impairs insulin action but does not Caffeine passes into breast milk in small
necessarily affect blood sugar (glucose) amounts and may build up in the nursing
levels in young, healthy adults. However, if baby. Studies have shown that babies may
you have type 2 diabetes, the impact of appear jittery and have trouble sleeping
caffeine on insulin action may be associated when their mothers drink large amounts of
with a small but detectable rise in blood caffeine-containing beverages. 13

sugar levels, particularly after meals. About

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Gout headache onset, regardless of headache

type.27

Preliminary research suggests that an extra

jolt or two of caffeine may trigger
Fertility
a gout attack in people with the painful and
often disabling arthritic condition.
Caffeine reduces muscle activity in the
Drinking four servings of caffeinated fallopian tubes that carry eggs from a
beverages in 24 hours is associated with an woman's ovaries to her womb. Caffeine
80% increased risk of recurrent gout attacks. stops the actions of specialized pacemaker
cells in the wall of the tubes.

Incontinence
These cells coordinate tube contractions so
that when they are inhibited, eggs cannot
In a study from the University of Alabama
move down the tubes. The authors of the
evaluating data on 1,356 women who
study say the findings provide an
reported taking in 329 mg of caffeine a day -
explanation as to why women with high
about three cups of coffee or more - 70%
caffeine consumption often take longer to
had a higher likelihood of having a bladder
conceive than women who do not consume
problem. Excess caffeine increases the
caffeine. Caffeine can reduce a woman's
likelihood of urinary incontinence in
chances of becoming pregnant by about
women.
27%.

Insomnia
Menopause
Results from a study published in
A recent study published in The Journal of
the Journal of Clinical Sleep
The North American Menopause
Medicine showed that consuming caffeine 3
Society showed that menopausal women
and even 6 hours before
who consumed caffeine had a greater
bedtime significantly disrupts sleep - even
degree of vasomotor symptoms. 28

when consumed 6 hours before bedtime, it

reduced objectively measured total sleep
time by more than 1 hour. Dangers of mixing alcohol and energy
drinks
Headaches
Energy drinks are beverages that typically
contain caffeine, other plant-based
A population-based study published
stimulants, simple sugars and other
in Neurology found that dietary and
additives. They are very popular among
medicinal caffeine consumption appears to
young people and are regularly consumed
be a modest risk factor for chronic daily
http://www.medicalnewstoday.com/articles/285194.php at 06.15;November 17th 2014

by 31% of 12- to 17-year-olds, and 34% of of coffee had a 21% increase in all-cause
18- to 24-year-olds.14
mortality.

When alcoholic beverages are mixed with

Studies suggest that moderate amounts of
energy drinks, a popular practice among
caffeine are not harmful. How much is
young people, the caffeine in these drinks
moderate? One hundred to 200 mg (one to
can mask the depressant effects of alcohol.
two 5-ounce cups of coffee) each day is the
limit that some doctors suggest, but each
Drinkers who consume alcohol mixed with
person is different. How caffeine affects
energy drinks are three times more likely to
people varies with their size, their sex, and
binge drink (based on breath alcohol levels)
how sensitive they are to caffeine's effects.
than drinkers who do not report mixing
Experts agree that 600 mg (four to seven
alcohol with energy drinks. They are also
cups of coffee) of caffeine or more each day
twice as likely to report being taken
is too much. 3

advantage of sexually, taking advantage of

someone else sexually, or riding with a
Caffeine allergy
driver who was under the influence of Caffeine sensitivity is determined by the
alcohol. efficiency of the human body to process and
metabolize caffeine. It is not the same as

Death caffeine tolerance, which describes how the

body responds to caffeine over time. 17

Death by caffeine might sound unlikely, but

Sensitivity has more to do with a person's
it can and has happened.
unique genetic makeup, as this determines
to what degree a given amount of caffeine
The FDA knows of a 19-year-old college
will affect a person.
student who died after taking an overdose of
caffeine tablets to stay awake. A caffeine
Caffeine is metabolized by the liver using
tablet contains as much caffeine as one to
the enzyme CYP1A2. The ability to produce
three 5-ounce cups of coffee. 3

this enzyme is regulated by the CYP1A2

A single teaspoon of pure caffeine is roughly
gene. Slight changes in the DNA sequence
equivalent to the amount in 25 cups of
of this gene determines how efficiently a
coffee. Pure caffeine is a powerful stimulant,
person can metabolize caffeine and thus
and very small amounts may cause
eliminate it from the body.
accidental overdose. Parents should be
aware that these products might be Some people genetically produce very little
attractive to young people.5
of this enzyme while others produce a large
amount. The majority of humans are
A Mayo Clinic partnered study found that
somewhere in the middle. 10% of the
men who drank more than four 8 fl oz cups
population are rapid caffeine metabolizers
and not sensitive to caffeine. 2
http://www.medicalnewstoday.com/articles/285194.php at 06.15;November 17th 2014

The third genetic link to caffeine sensitivity Some people could be normal but lean
involves the type of adenosine receptors a toward the hypersensitive or hyposensitive
person has in their brain. Those lacking the categories. Human genetics are complex
correct adenosine receptors in their brain and people are unique with many subtle
are unresponsive to the awakening effects genetic variations.
of caffeine because the caffeine molecule
cannot properly bind to the receptors. 3
Caffeine overdose

The most recent research from The Harvard Ingesting massive doses of caffeine all at

School of Public Health found six new once is particularly dangerous as the body

genetic variants associated with the way does not have time to react accordingly.

people metabolize and form addiction to Overdose symptoms serve as a warning

caffeine. system from mild to severe and consist of:

The 120,000-person study revealed:

Ingesting massive doses of caffeine all at once
 Two genes related to how caffeine is should be avoided as it can cause numerous health
metabolized problems.

 Two genes associated with how we feel  Jitters, restlessness, and nervousness
rewarded from caffeine
 Increased heartbeat
 Two genes that regulate fat and sugar in
 Nausea
the blood stream as a response to
caffeine.  Anxiety
 Heart palpitations
Based on the genetic data, people can be
 Insomnia
identified with three distinct levels of caffeine
sensitivity, determining to what degree the  Sweating
effects of caffeine will be realized:
 Dizziness

1. Hypersensitive to caffeine: react to  Vomiting

very small amounts of caffeine. Even at
 Cardiac arrest.
amounts less than 100 mg

2. Normal sensitivity to caffeine: can If these symptoms are recognized, further

usually have 200-400 mg of caffeine caffeine intake should be stopped in order to

daily without any adverse reactions avoid more serious and even life-threatening
symptoms.
3. Hyposensitive to caffeine: process
caffeine so efficiently that these people
Caffeine intoxication is included in the DSM-
report taking large doses (>500 mg)
5 physicians manual.
without much effect at all.
http://www.medicalnewstoday.com/articles/285194.php at 06.15;November 17th 2014

The official diagnosis can be made when

any five of the following symptoms are
present: restlessness, nervousness,
excitement, insomnia, flushed face, diuresis,
gastrointestinal disturbance, muscle
twitching, rambling flow of thought and
speech, tachycardia or cardiac arrhythmia,
periods of inexhaustibility or psychomotor
agitation.

There are mechanisms built into the human

body to prevent excessive consumption and
this includes caffeine overdose. Well before
toxic level, a person would experience side
effects to prevent them from consuming
more - nausea and vomiting.

Before the 149 or so cans of caffeinated

energy drink that it would take to kill an
average adult male, vomiting would most
certainly occur.

Since caffeine is consumed so widely, there

are a lot of half-truths, hearsay, urban
legends, media hype and even fiction often
surrounding the substance.

Written by Hannah Nichols

Copyright: Medical News Today