By Kristin Sheppard
How
much caffeine do you drink daily? I know that my daily intake is relatively
high compared to some of my friends, but low compared to others. In the morning
I make myself 12 ounces of coffee and mix it with 2 packets of hot chocolate
mix to help me wake up (it’s my own cheap version of a mocha!). By midday I’m
feeling tired again so I either get a latte from the library patisserie or a
bottle of soda. And at night I have another soda to help me focus on my
homework. According to the “Caffeine Content in Common Drinks and Foods” chart
created by the University of Washington, I’m drinking about 320mg of caffeine
daily, not counting any chocolate I may eat. It turns out, this amount of daily
caffeine intake is fairly normal, and considered to be safe by the Food and
Drug Administration (the FDA). The FDA reports that many doctors consider a
moderate amount of caffeine consumed daily to be safe, but what is a moderate
amount of caffeine? According to the doctors that the FDA consulted, it’s about
200mg of caffeine daily (oops, I guess I’m a little over) and a dangerous level
is about 600mg of caffeine daily.
Caffeine Content in Common Drinks and Foods |
But
what does caffeine do to your body? It has been found in mice that caffeine
binds to certain receptors in neurons and heart tissue. Remember that neurons
are cells that are involved in your nervous system and the receptors are part
of what allows cells to communicate with each other. One of these receptors is
A1-adenosine receptor. A1-adenosine
receptors are known to be located in many different parts of your body,
including your brain and your heart. When this receptor is stimulated it is
known to stop the release of excitatory neurotransmitters in the brain, meaning
that it is less likely that the neuron with the A1-adenosine
receptor will communicate with the next neuron. However, when caffeine binds it
stops the activity of these A1-adenosine receptors. This means that
when caffeine is present, more excitatory signals will be fired between
neurons. Binding of caffeine to these receptors in the heart also leads to a
change the strength, rate and conductivity of the heartbeat.
There
have been a number of studies on caffeine and how it affects hypertension (high
blood pressure) in adults and adolescents, arrhythmias (problems with the rate
or rhythm of your heart beat), and several other cardiovascular diseases. In
every study and review that I have read, it shows that administering
200-300mg of caffeine in pretty much any form has no long-term affect on any
individual of any age group (excluding very young children and infants, there
have not been many reports on this age group). The closest thing to a dangerous
result was reported in a study done in 2011 by Arthur Euman Mesas et al; they
found that administering 200-300mg of caffeine to adults who already have
hypertension, but do not regularly drink caffeine, have a sudden, short-term
increase in blood pressure lasting approximately 3 hours. However, similar
results were not found for individuals who had hypertension and drank coffee
daily for 2 weeks, nor did they find any link between long-term coffee
consumption and heart disease.
Moderate amounts of coffee have been shown to be safe for daily consumption |
Although
these studies are useful for telling me that I’m not going to have a heart
attack from drinking my daily coffee and soda, they do have their limitations. Every
study I have read relies on self-report of how much caffeine an individual
drinks or the people they study are only administered a moderate dose of
caffeine. However, people can only be administered what is thought to be a safe
dose of the drug by scientists who are studying the effects. It is unethical to
knowingly deliver something that may be dangerous to the individuals
participating in the study. This means that in humans a direct cause-and-effect
for too much caffeine cannot be studied. We must rely on those reports from
individuals who have claimed to have adverse reactions to high doses of
caffeine to try and find a relationship between caffeine and these undesirable
symptoms.
So
what happens when you start getting to those dangerous doses? Just like any
other drug, you can overdose. Symptoms of caffeine overdose in adults can
include trouble breathing, irregular heart beat, rapid heart beat, muscle
twitching, hallucinations, changes in alertness, confusion, sleeping trouble, convulsions,
diarrhea, dizziness, fever, increased thirst, increased urination, or vomiting.
Although
these symptoms can be frightening, it is easy to think that it would be fairly
difficult to consume that much coffee or soda in one day, and this may be true.
But the fairly recent introduction of energy drinks and caffeine pills
increases the risk of overdose. One of the more popular energy drinks that I
see people drinking is “Monster Energy.” Did you know one 24-ounce can of “Monster Energy”
contains 240mg of caffeine? That means that after one can of this stuff you should be
done with caffeine for the day. So what about if you drink two or three cans?
According to the FDA there have been 40 alleged adverse event reports since
2004 related to "Monster Energy" products alone. These reports include everything
from non-serious illnesses to life threatening hospitalizations, and even five
cases of death. Those numbers pale in comparison to the 92 reports (including
12 deaths) allegedly related to the also popular “5 Hour Energy” that have been
filed with the FDA since 2005.
Popular energy drinks available at most grocery and convenience stores |
So
what can we take away from all of this? I think that the best thing to remember
is that even though caffeinated beverages may be delicious and
deliver that extra boost you need to get through the day, try to keep it in
moderation. Although a moderate amount may be appetizing and pleasurable, too much can be
dangerous.
Works Cited:
Artin, B., M.
Singh, C. Richeh, E. Jawad, R. Arora, and S. Khosla. 2010. Caffeine-Related
Atrial Fibrillation. Journal of Therapeutics. 17:e169-e171.
Green, R.M., and
G.L. Stiles. 1985. Chronic Caffeine Ingestion Sensitizes the A1
Adenosine Receptor-Adenylate Cyclase System in Rat Cerebral Cortex. The Journal
of Clinical Investigation. 77:222-227.
Klatsky, A.L., A.S.
Hasan, M.A. Armstrong, N. Udaltsova, and C. Morton. 2011. Coffee, Caffeine, and
Risk of Hospitalization for Arrhythmias. The Permanente Journal. 15(3):19-25.
Linden, J. 1991.
Structure and function of A1 adenosine receptors, The Journal of the
Federation of American Societies for Experimental Biology. 5:2668-2676.
Mesas, A.E.,
L.M. Leon-Munoz, F. Rodriguez-Artalejo, and E. Lopez-Garcia. 2011. The effect
of coffee on blood pressure and cardiovascular disease in hypertensive
individuals: a systematic review and meta-analysis. The American Journal of
Clinical Nutrition. 94:1113-1126.
Savoca, M.R.,
C.D. Evans, M.E. Wilson, G.A. Harshfield, and D.A. Ludwig. 2004. The
Association of Caffeinated Beverages With Blood Pressure in Adolescents. Archives
od Pediatric & Adolescent Medicine. 158:473-477.
Seifert, S.M.,
J.L. Schaechter, E.R. Hershorin, and S.E. Lipshultz. 2011. Health Effects of
Energy Drinks on Children, Adolescents, and Young Adults. Pediatrics.
127(3):511-528.
Shi D., O.
Nikodijevic, K.A. Jacobson, and J.W. Daly. 1994. Effects of Chronic Caffeine on
Adenosine, Dopamine and Acetylcholine Systems in Mice. Archives Internationales
de Pharmacodynamie et de Therapie. 328(3):261-287.
Temple, J.L.
2009. Caffeine use in children: What we know, what we have left to learn, and
why we should worry. Neuroscience and Behavioral Reviews. 33:793-806.
2012. CFSAN
Adverse Event Reporting System, Voluntary and Mandatory Reports on 5-Hour
Energy, Monster Energy, and Rockstar. U.S. Department of Health and Human
Services, Food and Drug Administration. <http://www.fda.gov/downloads/AboutFDA/CentersOffices/OfficeofFoods/CFSAN/CFSANFOIAElectronicReadingRoom/UCM328270.pdf>
Very interesting Kristin. I too am probably way over on my daily coffee consumption. I've also heard that caffeine can stimulate the adrenal glands to produce increased levels of adrenaline, is this true?
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