Originals: COFFEE: More Than Caffeine


COFFEE: More Than Caffeine

What is Coffee?

The known and most preferred source of caffeine is coffee. The United States traces the discovery of coffee back to the saga of goat herder Kaldi, according to the National Coffee Association. This takes us back to the 850s after Christ.[1].

Although we do not have much opportunity to examine the veracity of the legend, we know that there is of course a great difference between the meaning of coffee for us today and the meaning it carries with Kaldi. Coffee is one of the most consumed beverages in the world today. It is also an important source of caffeine for many consumers. By doing a very simple research today, of course, the effects of coffee on human health can be investigated. However, one of the most important issues to examine here is the effects of caffeine on the human body, rather than the sociocultural meaning of coffee.

I would rather suffer with coffee than be senseless

-Napoléon Bonaparte

What is Caffeine?

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Caffeine is rapidly absorbed from the gastrointestinal tract into the circulatory system after consumption, reaching its maximum plasma concentration 30 to 60 minutes after consumption. However, it can take effect between 15 and 120 minutes depending on the density in the digestive system.[6].

Caffeine is a psychotropic (central nervous system stimulant) substance of the (C8H10N4O2) methylxanthine class. While it can be found not only in coffee beans, but also in some cocoa beans and plant leaves such as tea, it is also found in more than 60 plants. The effects of the activation of caffeine at the cellular level can be examined in three ways; antagonism of adenosine receptors, intracellular calcium storage and inhibition of phosphodiesterases in the central nervous system [2], [6].

Basically, we can say that the target for the mechanism of caffeine is adenosine receptors in the brain. Because caffeine is both fat and water soluble, it can easily cross the blood-brain barrier and blood-testicular barrier and act on four adenosine receptors of type A1, A2a, A2b and A3. But specifically, stimulation of the A2a receptor is responsible for the wakefulness effects of caffeine[2], [3], [6]. Since caffeine blocks adenosine receptors, it causes an increase in reflex activation of the sympathetic system in conscious patients. Sympathetic system is active in regular coffee consumers, but this does not cause a significant increase in peripheral vascular resistance; In those who do not consume coffee, it has been observed that coffee stimulates the sympathetic system and increases arterial pressure. Regular coffee consumption has also been observed to have an effect on the autonomic nervous system and arterial pressure, with a possible development of tolerance[8].

Other mechanisms of action, such as intracellular mobilization of caffeine and inhibition of phosphodiesterases, are unlikely to be possible with daily caffeine intake, but can be observed in individuals using high doses [6].

Caffeine clearance is the main enzyme responsible for the metabolism of caffeine. Only 0.5% to 2% of ingested caffeine is excreted in the urine as well. The half-life of caffeine in humans generally ranges from 2 to 12 hours, due to differences in absorption and metabolism. Paraxanthin, the main metabolite of caffeine, has a similar chemical structure and half-life to caffeine, but its serum concentration is more stable for one day compared to caffeine. It becomes higher between 8 and 10 hours after ingestion. Although paraxanthin has a similar effect to caffeine, daily caffeine consumption biologically causes high levels of both caffeine and paraxanthin. [6].

Studies do not support that caffeine has a significant effect on concentration, but there are studies suggesting that it may play an important role in increasing processing speed. In the studies, most of the caffeine given to adults and the elderly population has significant positive effects on both short and long-term memory, while children argue that it is not effective. [9].

Effects of Caffeine

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In addition, caffeine has approved the use of caffeine for the treatment of apnea of ​​prematurity and the prevention of bronchopulmonary dysplasia (chronic lung disease) of premature infants, according to the United States Food and Drug Administration (FDA). In addition, the FDA has approved the use of caffeine due to its effects such as migraine headaches and increasing athletic performance [2]. (Consult your doctor before use.)

Caffeine can have mild or fatal side effects associated with long-term use. The most severe and common adverse events are usually associated with cardiac arrhythmia, hypertension, myocardial infarction, electrolyte disturbances, and aspiration[4], [5].

Caffeine Addiction

Even without looking at many recent studies, it is not difficult to observe that caffeine addiction is on the rise. According to a study conducted in the United States, more than 90% of adults regularly consume caffeine, and this consumption is more than 200mg per day [8].

There are studies showing that caffeine addiction, like other addictions, is partially affected by the genotype. Withdrawal symptoms of caffeine addiction are similar to those of nicotine and alcohol. [7].


[1] “The History of Coffee.” Ncausa.org, 2022, https://www.ncausa.org/about-coffee/history-of-coffee
‌[2] Evans, Justin, et al. “Caffeine.” Nih.gov, StatPearls Publishing, May 2022, www.ncbi.nlm.nih.gov/books/NBK519490/.
[3‌] Ferré, Sergi. “An Update on the Mechanisms of the Psychostimulant Effects of Caffeine.” Journal of Neurochemistry, vol. 105, no. 4, May 2008, pp. 1067–79, https://doi.org/10.1111/j.1471-4159.2007.05196.x.
[4] Kerrigan, Sarah, and Tania Lindsey. “Fatal Caffeine Overdose: Two Case Reports.” Forensic Science International, vol. 153, no. 1, Oct. 2005, pp. 67–69, https://doi.org/10.1016/j.forsciint.2005.04.016.
[5] Lara, Diogo R. “Caffeine, Mental Health, and Psychiatric Disorders.” Journal of Alzheimer’s Disease, edited by Rodrigo A. Cunha and Alexandre de Mendonça, vol. 20, no. s1, Apr. 2010, pp. S239–48, https://doi.org/10.3233/jad-2010-1378.
[6] Cappelletti, Simone, et al. “Caffeine: Cognitive and Physical Performance Enhancer or Psychoactive Drug?” Current Neuropharmacology, vol. 13, no. 1, Apr. 2015, pp. 71–88, https://doi.org/10.2174/1570159×13666141210215655.
[7] Meredith, Steven E., et al. “Caffeine Use Disorder: A Comprehensive Review and Research Agenda.” Journal of Caffeine Research, vol. 3, no. 3, Sept. 2013, pp. 114–30, https://doi.org/10.1089/jcr.2013.0016.
[8] Frary, Carol D., et al. “Food Sources and Intakes of Caffeine in the Diets of Persons in the United States.” Journal of the American Dietetic Association, vol. 105, no. 1, Jan. 2005, pp. 110–13, https://doi.org/10.1016/j.jada.2004.10.027.
[9] Fiani, Brian, et al. “The Neurophysiology of Caffeine as a Central Nervous System Stimulant and the Resultant Effects on Cognitive Function.” Cureus, May 2021, https://doi.org/10.7759/cureus.15032.‌

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