CAFFEINE - chem.ku.edu€¦ · Caffeine is also used in premature babies who suffer from apnea, or...
Transcript of CAFFEINE - chem.ku.edu€¦ · Caffeine is also used in premature babies who suffer from apnea, or...
CAFFEINE JUMP TO:
Introduction
Chemical Information
Decaffeination
Caffeine in Food and Drink
Caffeine and Your Metabolism
Pregnancy and Caffeine
Deadly Dosage of Caffeine
Medicinal Uses
Side Effects of Caffeine
Mixing Caffeine with Other Substances
Introduction to Caffeine and Your Body
Caffeine as a CNS Stimulant
Caffeine and Neurotransmission
Caffeine’s Psychoactive Properties
Caffeine Dependency
Metabolism of Caffeine by the Body Part 2
INTRODUCTION TO CAFFEINE
85% of the United States population consumes a caffeinated
beverage daily, if not more (1) . The most common method of
consumption was through coffee with tea and soda not far behind for
citizens under the age of 18. While scientists have found that 400 mg
per day have no adverse health effects, high caffeine intakes have
been seen to correlate with “anxiety, headaches, nausea, and
restlessness.” Because of these, and many other factors, caffeine
has become the most researched “food component.” Its effects,
positive and negative, and uses are widespread (1).
CHEMICAL INFORMATION
Physical Properties-
Caffeine is a white powder with a very bitter taste in its most common
form (See Figure 2) . It can also be found as a group of “white
glistening needles (2).” Caffeine’s molecular weight is 194.2 g/mole.
The nitrogen and oxygen atoms are highly electronegative and
therefore attracts the hydrogen atom. This results in caffeine being
soluble in water as these hydrogen bonds can be created in six
places on the molecule (3). The melting point of caffeine is 235°C
and the boiling point is 178°C (4). No natural isomers of caffeine
exist. Isomers are molecules that have different molecular structures
but the same chemical formula. Caffeine has no stereoisomers as
there are no tetrahedral structures, with all different substituents,
preventing a chiral center (See Figure 1).
Figure 1-
The figure above is the 3D molecular structure of caffeine. The
model shows hydrogen atoms (white), Nitrogen atoms (blue), Carbon
atoms (green) and oxygen atoms (red) bonded together. All but one
of the nitrogen atoms are trigonal planar, meaning they have 3
substituents around the atom.
Figure 2-
The figure above shows Caffeine in its pure, extracted form. Caffeine
can be formed in this powdery substance or can be crystalized and
maintained both at room temperature.
The Intermolecular Forces - Intermolecular forces are the “various
forces of attraction that may exist between the atoms and molecules
of a substance (5).” The weakest of these forces are the London
Dispersion forces. London
Dispersion forces are the result of the constant motion of the
electrons in the atom or molecule. This force creates two types of
dipoles: an instantaneous dipole, when the electrons are distributed
asymmetrically, an induced dipole, a dipole which distorts the
electrons of a neighboring atom or molecule. The strongest force
occurring in the caffeine molecule is the Dipole-Dipole force. The
Dipole-Dipole attraction is the “electrostatic force between the
partially positive end of one polar molecule and the partially negative
end of another (5).” These charged ends of the molecules are
attracted to one another and, therefore, create the intermolecular
force that occurs between the molecules.
Polarity - We know caffeine is polar as polar molecules dissolve in
polar substances, and, as stated earlier, caffeine dissolves in the
polar molecule water. However, we also know that caffeine is polar
because of its structure. The Carbon atom have a weaker dipole then
the Nitrogen and Oxygen atoms. Therefore, they will move the
electrons toward the stronger bonds. Increasing electrons near the
Nitrogen and Oxygen molecules increases the negative charge
around these bonds and decreasing the negativity around the carbon
molecules. This results in the polar molecule caffeine.
DECAFFEINATION
Caffeine is a xanthine alkaloid that is mostly found in the leaves and
beans of the coffee tree, tea and cocoa. Caffeine can also be found
in yerba mate, guarana berries. the kola nut and the Yaupon holly
(6). Because caffeine is found in plants, to obtain pure caffeine it
must be extracted from the plants. This pure caffeine is artificially
placed in foods, drinks, and medication. Caffeine is an alkaloid,
meaning it is mostly made up nitrogen. There are multiple means
through which the extraction of caffeine can occur, the first method
being the solution method. The plant is processed to “obtain aqueous
solutions of the alkaloids.” The alkaloids are removed and the
solutions and the pure substance is extracted(7). The coffee beans
are steamed and soaked to remove the caffeine. The solvents most
commonly used for this process are ethyl acetate or methylene
chloride because they are more efficient and have a lower toxicity.
The next method, differs slightly from the first. The water process hot
water to soak the coffee beans. This water, now filled with coffee
flavor and caffeine molecules is passed through carbon filters to
collect the caffeine molecules. The water which passes through is
now caffeine free. This process is the most common for organic
coffee beans. This process is natural however it isn’t specifically
designed for caffeine therefore “it only removes 94 to 96 percent of
the caffeine (8).” Lastly, the least used method: The Supercritical
Carbon Dioxide Method. This method uses carbon dioxide under
high temperatures and pressures. This causes the CO2 to act like a
gas and a liquid. It goes into the beans as a gas but the “dissolves
[the] caffeine like a liquid.” Because it is exposed to the supercritical
CO2 for hours at a time, the decaffeinated CO2 evaporates and the
beans are left caffeinated with all the flavor intact (9) .
CAFFEINE IN FOOD AND DRINK
Originally, caffeine was only available in its organic form, plants that
contained the alkaloid. As science evolved, scientists found a way to
add caffeine to all types of food and drinks. Scientists have now
added this molecule to over 800 products for consumption (See
Table 1) . Caffeine is FDA regulated and does have a lethal dose;
however, the lethal doses of the most common sources of caffeine
would be difficult to reach without intention. To find just how much
caffeine is safe or even healthy in the most common products there
are calculators based on your weight and the content of caffeine.
Other factors can influence this amount. These factors include “ a
person’s tolerance, sensitivity, weight, age and health history (10) .”
(To find your lethal and safe doses by weight, visit this calculator.)
Table 1-
Product Caffeine Content
Brewed Coffee 163 mg
Baking Chocolate 23.2 mg
Excedrin Migraine 65mg
Lipton Tea 55mg
Coca-Cola 34mg
Red Bull 80mg
The table above was produced using Caffeine Informers lethal dose
calculator. The products were chosen as they make up the most
common products through which caffeine is consumed. 300-400 mg
is the average safe daily intake for healthy adults.
CAFFEINE AND YOUR METABOLISM
Caffeine metabolizes in the body due to the cytochrome P450
enzyme in the liver, where factors like genetics, diet and habits can
affect the activity of this enzyme and the half life of the caffeine itself.
When initially synthesizing the protein, a person’s genetic code
decides how much of the enzyme is made. Increased production of
this protein increases clearance of caffeine from a person’s system,
meaning the effects of caffeine do not last as long. Consumption of
grapefruit juice prolongs the half life of caffeine and decreases the
clearance of the substance, while consumption of foods high in
Vitamin C increase the clearance rate of caffeine from the body
through stimulation of the P450 enzyme. Finally, smoking doubles
the rate of clearance of caffeine in the body. Oral contraceptives,
namely birth control, nearly doubles the half-life of caffeine,
decreasing the effectiveness of the ‘buzz’ a person achieves while
consuming it. Pregnancy also affects the metabolism of caffeine, as
the P450 enzyme is less active in clearing the substance from the
body, particularly during the third trimester. The half life of caffeine
also increases, but metabolism of the substance will return to normal
a few weeks after delivery when bodily hormones and chemicals
level out [11].
PREGNANCY AND CAFFEINE: MOSTLY A NO-NO
Caffeine consumption is typically frowned upon when a woman
is pregnant. Associations between low birth weight (being defined as
a weight of less than 2,500 grams) and consumption of caffeine were
found, and that the risk of a baby having low birth weight increases
linearly as caffeine consumption increases [12]. Another study found
that increases of 100 milligrams per day of caffeine were associated
with a 13% higher risk of low birth weight [13]. Caffeine has structure
that is similar to that of the purine molecules in DNA, which has the
potential to affect cell division and metabolism, since the enzymes
necessary for the digestion of caffeine do not manifest until several
days after birth [25]. Other side effects of caffeine consumption
include an increased risks of birth defects and miscarriages [14,15].
Maybe just switch to decaf coffee and lay off the Red Bulls if you’re
expecting.
DEADLY DOSAGE OF CAFFEINE
Finals got you down? Be careful with the amount of caffeine
you ingest. Caffeine overdose is rare, as your body will stop you from
eating or drinking the amount of food or drink that it would take to
reach the deadly level. However, if taking solid caffeine, in the form
of powder or pill, overdosing is very possible. A lethal dose of
caffeine is considered to be around 10 grams (which varies from
person to person) according to healthline.com [16], but according to
the Material Safety Data Sheet (MSDS) for
caffeine, the lethal dose for 50% of the test
group (LD50) of caffeine is considered to be
194 milligrams for every kilogram weighed
[15]. The typical way of death by caffeine is when cardiac arrest
occurs from overconsumption [17], as caffeine increases heart rate,
increases blood pressure, and affects the flow of blood, which all
lead to cardiac related problems.
MEDICINAL USES
Caffeine is used in conjunction with painkillers like aspirin or
acetaminophen to treat headaches and migraines. During a
migraine, blood vessels in the brain enlarge. Caffeine counteracts
this, as it contains vasoconstrictive properties. When used in
conjunction with painkillers, it increases the effectiveness of the
medication [18]. Caffeine is also a diuretic,
though not enough research has been done to
fully explain its mechanisms. It is postulated that
caffeine blocks the reabsorption of sodium in the
kidneys and that it increases the filtration rate in
the kidneys by contradicting the instated vasoconstriction [19].
Caffeine is also used in premature babies who suffer from apnea, or
the cessation of breathing for longer than 15 seconds. This treatment
reduced the episodes for shortness of breath in infants [20,21].
Caffeine can also be used to treat asthma, exhaustion, and other
types of pain. It is also effective for reducing the risk of developing
Parkinson’s disease, gallbladder disease, and type 2 diabetes.
SIDE EFFECTS OF CAFFEINE
Consumption of caffeine can cause pupil dilation, increase in
rate of breathing, increased heart rate, constriction of blood vessels
which causes a decrease of blood flow to cuts and increases the flow
of blood to muscles, increased blood pressure, decreased blood flow
to stomach which causes slower digestion, a release of sugar from
the liver causing an increase in energy, and tightening of muscles
[22].
MIXING CAFFEINE WITH OTHER SUBSTANCES
When mixing caffeine with alcohol, caffeine masks the
depressant effects of the alcohol, causing the consumer to feel more
alert than they actually are and the consumer may consume more
alcohol and increase impairment as a result. The effects of mixing
caffeine and alcohol are not completely understood.
However, it is known that both alcohol and caffeine
interact with adenosine neurotransmission, and interfere
with one another [26]. Caffeine does not actually sober you up when
consumed (sorry to disappoint) [23].
Mixing caffeine and marijuana actually increases the
effectiveness of the drug, as both THC, also known as
Tetrahydrocannabinol, and caffeine release dopamine in the brain.
Though this may sound like a good, hold your stoner horses.
Caffeine also increases the risk of addiction to weed when the
substances are combined, or rather increases the risk of being
addicted to the feeling of being high [24].
INTRODUCTION TO CAFFEINE AND YOUR BODY
Caffeine is found in a massive variety of everyday products,
including coffee, soda, chocolate, and even medications, such as for
headache relief. Because of the ubiquity of caffeine-containing
products in our society, it is important to understand how these
myriad products use the effects of caffeine on our bodies to bring
about their intended results.
CAFFEINE AS A CNS STIMULANT
Caffeine is a central nervous system (CNS) stimulant, meaning
that it increases activity of the CNS [28][29]. This stimulation
manifests itself in the form of heightened alertness, elevated heart
rate, and increased blood pressure, among other physiological side
effects. These effects are what most people experience after having
a few cups of coffee or soda. Although most people know what kinds
of effects caffeine has on the body, fewer know how caffeine causes
these physiological changes.
To understand how caffeine specifically stimulates the CNS,
one must first understand the basis of the nervous system. Nerve
cells, called neurons, are comprised of several key regions: cell body
(A.K.A. soma), dendrites, axon, and axon terminals. The cell body
houses the nucleus and other organelles important for the neuron’s
survival. The dendrites are branched protrusions from the cell body
that connect the cell body of one neuron to the axon terminals of
another neuron. The axon is a long, slender structure along which
an action potential is transmitted from the cell body to the axon
terminals. An action potential is essentially just an electrochemical
potential that can move from one neuron to another along axons,
chiefly used to transmit information across the whole body. The
axon terminals are structurally similar to dendrites in that they are
branched protrusions that connect neurons. However, axon
terminals have an especially important function: They release
neurotransmitters packaged in vesicles—small, membrane-bound
sacs—into the synaptic cleft, a small space between one neuron’s
axon terminals and another’s dendrites. The neurotransmitters are
then absorbed by the dendrites of the next neuron, which triggers the
start of an action potential down the next neuron’s axon, and so forth.
This basic system is how the nervous system acts as a line of
communication throughout the entire body using electrochemical
messages in the form of neurotransmitters.
CAFFEINE AND NEUROTRANSMISSION
With caffeine, specifically, the release of antagonists, which are
substances that bind to a receptor and block agonistic binding or
activation, to A1 and A2A adenosine receptors is triggered as it is
digested and absorbed, which promotes the neurotransmitter release
of acetylcholine [30]. This antagonism with adenosine is responsible
for the wakefulness experienced after consumption of caffeine, as it
stops adenosine from binding to its receptors, which typically causes
sleepiness as a part of one’s normal circadian rhythm
[31]. Additionally, the release of acetylcholine causes stimulation of
neuromuscular junctions, which can cause those who consume
caffeine to feel jittery or hyperactive. Thus, the primary effect of
caffeine consumption with which most people are very familiar has
an interesting biochemical and physiological reason behind it!
CAFFEINE’S PSYCHOACTIVE PROPERTIES
In addition to its properties as a CNS stimulant, caffeine is also
a psychoactive substance, meaning that it primarily affects the CNS
by changing brain function [32][33]. It has variable effects on a
person’s memory and ability to learn and can either improve or
decrease one’s capability to retain information. Due to its properties
as a stimulant, caffeine can contribute to significantly augmented
concentration, coordination, dexterity, and reaction time. These
changes in one’s alertness and wakefulness are why many people
will grab a cup of coffee every morning to help brush away any
lingering sleepiness. However, it is critical that more people
understand the potentially adverse effects that consumption of large
amounts of caffeine might have because of how widespread
caffeine-containing products are all around the world.
CAFFEINE DEPENDENCY
Caffeine, as a CNS stimulant, when used regularly can
produce a mild physical dependence in users. The development of
such a dependence happens because of chemical reactions in one’s
brain, known as the reward system. “When exposed to a rewarding
stimulus, the brain responds by increasing release of the
neurotransmitter dopamine” [34]. This influx of dopamine causes
positive, happy sensations in the person. Repeated use of stimuli
that activate the reward system can lead to psychological
dependence on said stimuli and even full-blown addiction if the
effects of the stimulus is potent enough. In the case of caffeine,
addiction is much less grave than for more addictive stimuli like
nicotine or opiates, although mild dependences are fairly common in
instances where people often consume caffeine, which can cause
the repeated release of dopamine to reinforce the positive
physiological effects of that stimulus. If a person who has built up a
dependence on caffeine goes without it for a long period of time, he
or she might experience headache, fatigue, anxiety, irritability,
depressed mood, or difficulty concentrating [35]. But because of the
relatively mild consequences of caffeine withdrawal, most experts
consider caffeine addiction to be not serious.
METABOLISM OF CAFFEINE BY THE BODY PART 2
Caffeine is metabolized exceptionally well by the human body,
with 99% of caffeine being absorbed within 45 minutes of
consumption [36]. Because of this very rapid metabolism, it takes
very large amounts of caffeine to be consumed before seriously
adverse effects come about, typically on the order of whole grams of
caffeine. Also because of the rapid metabolism of caffeine in the
body, its effects as a CNS stimulant are fairly immediate. This is
easily observable when a person who is feeling groggy after just
having woken up drinks a cup of coffee and quickly perks up, ready
for the coming day.
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