Caffeine

A brief history and the effects of increased usage

Caffeine has been a widely used drug for thousands of years. It's main usage has gradually shifted from a medical to recreational usage. Originally, the plants that the drug comes from were coveted; the drug itself is now extracted in large quantities and put into countless food and drink products to give people a spark of energy and decrease tiredness. Despite the increase in caffeine use in recent times, many people have little knowledge of the overall effects it has on their bodies.


    Caffeine has been used as a stimulant and source of energy for all of recorded history, and probably long before. Weinberg and Bealer in The World of Caffeine discuss how different cultures all around the world, long before they knew what caused the effects, used the plants that produce this drug for medical uses and to increase energy. It was not until 1819 that the drug caffeine itself was isolated as the source of the effects. Friedlieb Ferdinand Runge made the discovery in Europe as a result of the growing interest in plant chemistry that began there in the nineteenth century.[1]
    The discovery of caffeine by Runge occurred only because the famous poet Johann Wolfgang von Goethe gave Runge some mocha coffee beans as a gift, and told him to analyze them. Within a few months Runge was able to extract and purify caffeine from the beans. Four other scientists are credited with independently discovering caffeine soon after Runge without hearing of his work. From this point on caffeine was identified in many plants all around the world. Only a year later, in 1820, it was found that the thein in tea was also caffeine, but it was not until 1865 that it was discovered in cola nuts.[1]

Origins of Caffeine

    The oldest sources of caffeine that are commonly used today are tea, chocolate, coffee, and more recently,
Image: Tea Leaves, an Early Source of Caffeine
cola. One of the first plants discovered and used for the effects of its caffeine was the tea plant. Most people associate tea with China, as that is where European nations first learned about tea. Chinese legends claim tea was discovered by the first emperor of China who, while boiling water so that was safe to drink, had a tea leaf fall in. He then drank the result and wrote about it. This story, which reportedly took place in 2737 B.C.E. is not true because the earliest writings of tea in China date to about 200 B.C.E. These writings in the Shin Lun by Hua Tuo explain how tea could improve alertness and concentration, although it was not known at the time this was caused by the caffeine. The Chinese likely learned about tea from either natives of northern India, or tribesmen from Southeast Asia.[1]
Image: Cacao Beans

    The cacao bean is another common plant that has long been used for the effects of caffeine. Archaeological discoveries in Mexico have found the first use of the cacao bean to be by the Olmecs who lived in Mexico between 1500 and 400 B.C.E. The Olmecs harvested wild cacao pods to make a chocolate drink. Following the Olmecs, the Maya became very wealthy trading cacao. Within Mexico, chocolate was then passed on to the Toltecs and finally the Aztecs in twelfth century. In the early sixteenth century, the Spanish conquistadors first learned of chocolate from the Aztecs, and it was spread through Europe from there. Although the Maya were the first civilization of the New World to keep historical records, most information about the early use of cacao was lost when conquistadors and missionaries destroyed much of the culture. Mayans used the cacao bean as currency and it is estimated that “the daily wage of a porter in central Mexico was a hundred beans.”[1]
    Despite being the current primary source of caffeine, coffee did not make its appearance until the ninth century at the earliest in Ethiopia, and possibly not until the fifteenth century in southern Arabia. The late discovery of coffee is odd because the coffee bean naturally grew along trade routes between Ethiopia, Abyssinia, and the Middle East. Unlike chocolate and tea, coffee beans were originally often eaten instead of made into a drink. The Galla tribe of Ethiopia mashed the beans and mixed them with animal fat to make a filling and energizing food for war trips.[1]
    One of the most popular forms of caffeine currently is soft drinks. The 1830s saw the first flavored soft drinks which were actually considered “health drinks.” The original flavors came from bark and flowers added to the drinks which gave birth to sodas such as root beer, ginger ale, and lemon. Root beer was in wide distribution by 1876, and by 1881 so was the cola flavor which is made from cola nuts. While the cola nuts do add caffeine to sodas, today 95% of the caffeine in most sodas is added for extra effect. Due to current knowledge of the effects of caffeine, US regulations have limited the caffeine content of sodas to no more than 6 mg/ounce. This level of caffeine is much lower than the amount naturally found in coffee and tea.[2]


Increase In Caffeine Usage

    Caffeine has become the easiest drug to get a hold of, and is now used by most Americans every day. Since the properties of caffeinated plants were discovered long ago, we have not shown much restraint in caffeine intake. As more uses were found, people used the drug more. Tea has become extremely common in China and Asia. Western cultures have tended to drink lots of coffee, as well as tea. Once the drug could be extracted from plants, it was then used in all kinds of food and beverages to improve flavor and add the energy jolt that caffeine gives the body.
    Once caffeinated soft drinks were invented, they took off at an alarming rate. The drinks spread all over the world with various flavors that suited different cultures. By 1970, the average soft drink intake in the US was 24.3 gallons per person per year. While this staggering number created huge business opportunities, it was nothing compared to the rate of growth that was to come. People can never seem to have enough caffeine, which is evident by an intake which has more than doubled since then. By 1997 the average person drank 53 gallons per year.[2] Energy drinks were developed much later than soft drinks and did not become largely popular until fairly recently.
    The first energy drink, Lucozade, was first sold in 1938 by a pharmaceutical company in the United Kingdom. Energy drink companies then began to spring up in Asia and Austria. The Red Bull energy drink went on sale in Austria in 1987 and came to the United States ten years later, in 1997. Red Bull launched the current energy drink craze in North America and Europe. Energy drinks serve a much different purpose than soft drinks and have several physical differences as well. Energy drinks generally have less sugar, so they are less sweet, have less carbonation, and in addition to caffeine, contain other chemicals and drugs that act as stimulants. The energy drink market, unlike the soft drink market, is not controlled by large companies. Instead, many smaller competitors are fighting for niche markets. Energy drinks, which are targeted at a young market, are not currently regulated in the United States like soft drinks are and as such, they contain much higher concentrations of caffeine.[2]
    While caffeine has long been a common food and beverage item in the daily lives of many cultures, it has also been used as medicine. Many caffeinated plants, such as tea and coffee, were originally used as medications when they were first discovered. Caffeine is still used today in some medications. Besides being used in stimulant drugs intended to increase alertness and reduce fatigue, it is also used in diet aids, painkillers, and some cold remedies. Caffeine increases the metabolism and suppresses appetite which is why it is used in some diet aids. Many pain relievers contain caffeine because it is known to increase the effectiveness of basic pain relievers.[2]

Moderate Levels of Caffeine

    Caffeine is rapidly absorbed into the bloodstream by the body after oral ingestion. Its levels in the body can peak
Image: Caffeine and Adenosine Molecular Structures
in as little as fifteen minutes and be completely absorbed in just forty-five minutes. The most common way to take caffeine is orally. Since it targets the central nervous system, it goes straight to the bloodstream. Once in the bloodstream, caffeine attaches to plasma and rides to the brain, easily crossing the blood-brain barrier. When it arrives, caffeine acts as an antagonist and inhibits adenosine receptors. The blocked adenosine receptors lead to an increase of dopamine in the brain.[3] It is this imbalance in neurotransmitters in the brain that causes many of the known effects of caffeine. Dopamine helps with cognition, motor coordination, sleep, and mood, while adenosine helps promote sleep and suppress arousal. There is a direct correlation between the effects of these neurotransmitters and the effects caffeine has on people.[4]
    There are both common, well known effects of caffeine as well as lesser known long term effects. Caffeine is produced by plants to harm or kill insects, so it is a potent substance in small quantities. Some of the main physical effects of caffeine on humans are related to motor coordination, endurance, sleep, mood, anxiety, and depression. The pickup that people associate with caffeine comes from the fact that caffeine is a stimulant.[5] Pure caffeine is extremely toxic to humans. The chemical cannot be touched with bare hands and the fumes cannot be inhaled without serious effects. Because of this, suppliers cannot sell it to individual purchasers, but only to companies with licenses. The warning label on one bottle of caffeine reads:
Warning! May be harmful if inhaled or swallowed. Has caused mutagenic and reproductive effects in laboratory animals. Inhalation causes rapid heart rate, excitement, dizziness, pain collapse, hypotension, fever, shortness of breath. May cause headache, insomnia, nausea, vomiting, stomach pain, collapse and convulsions. May cause digestive disturbances, constipation, cardiac disorders, and depression. May cause epigastric pain, cardiac and respiratory disorders, and depressed mental state. Eye contact may cause irritation, redness, and conjunctivitis. Ingestion may produce gastrointestinal irritation, vomiting, and convulsions. Fatalities have been known to occur. Target organs affected: eyes, skin, central nervous system, respiratory and gastrointestinal tract.[1]
    Low doses of caffeine appear to increase motor coordination, while higher amounts decrease it below normal. Coordination improves with low doses because adenosine agonists depress this, but caffeine acts as an antagonist and blocks the adenosine from acting. At higher doses other receptors are effected which reverse this effect causing lowered coordination. The effect caffeine has on sleep is also partially caused by its blocking of adenosine receptors. As previously mentioned, adenosine promotes sleep, and since caffeine blocks it from the receptors, this wards off the feeling of sleep. Unfortunately, this can lead to insomnia and cause headaches. Caffeine also increases the rate that noradrenergic neurons fire, which helps to mediate sleep.[5] It does not, however, eliminate the need for sleep.
    Mood actually becomes more positive from low doses of caffeine, up to about 200mg. People report feeling “energetic, imaginative, efficient, self-confident, alert, able to concentrate, and motivated to work.”[5] Anxiety is generally only caused from excessive amounts of caffeine. Smaller amounts may trigger this in people who are sensitive or prone to anxiety attacks. The link between depression and caffeine intake is unclear. There is a correlation between increased caffeine intake and decreased depression, but it has yet to be proven to cause it.[5] An increased intake of caffeine also increases a person’s willingness to accept alternative ideas as well as raises performance levels on repetitive tasks.[6] It is important to note that these are reactions from intake of low to moderate levels of caffeine (20mg to 400mg).

Higher Levels of Caffeine

    After prolonged use of caffeine, the body can build up a tolerance to the drug. The number of adenosine receptors in the brain increases due to the amount of caffeine molecules blocking them. This has two effects on the body. First, it requires more caffeine to block the receptors and receive the same effects. Second, with more receptors, the effect of adenosine when there is no caffeine in the body is increased. This is what causes the withdrawal symptoms that approximately 22% of sensitive users get when they stop taking caffeine. When individuals slowly decrease their caffeine intake, withdrawal symptoms are not seen. This shows that the physical dependence created by caffeine is much weaker than that of commonly abused drugs such as amphetamines or nicotine.[5] Bealer mentions that complete tolerance to caffeine's effects can develop very quickly. With the large amounts of caffeinated beverages available, complete tolerance can develop in a matter of weeks.[5] Withdrawal effects are similar to those of other drugs and include craving, tiredness, confusion, and mild to severe headaches. These symptoms can last up to two weeks.[6]
    Due to the strength of caffeine, relatively small doses can be lethal. Orally ingesting as little as three grams has been known to cause fatalities. Because the tolerance of people varies greatly, there is at least one documented case of a woman surviving a twenty gram dose. The LD50 (median lethal dose) of caffeine in rats is 192 mg/kg. This means that a dose of 192 milligrams of caffeine per kilogram of body mass will kill 50% of mice. It is estimated that the LD50 for humans is between 150 mg/kg and 200 mg/kg but varies depending upon individual body build and sensitivity.[6]

Overdose

    Each year thousands of reports of caffeine overdose come into poison control centers. About half of all cases require immediate health care treatment. Most are intentional overdoses and many of those are suicide attempts. Despite the large number of overdoses, very few deaths each year are attributed to caffeine. In 2001, only one death was reported. Since caffeine leaves the body so quickly compared to other drugs, overdose is usually resolved quickly and there are generally no complications. The highest risk of an overdose becoming fatal is when caffeine reaches a level in the body that causes a person to lose consciousness. Another serious sign is seizures which requires immediate anti-seizure medication. Removing caffeine already in the body helps people recover from an overdose, but a charcoal hemoperfusion is one of the only ways to save a patient with a lethal dose.[7]  In a charcoal hemoperfusion, the patients blood is pumped out of their body and through a machine. Once in the machine, the blood is run over charcoal to purify it and remove the toxins.
    Scientists have been examining whether excessive caffeine intake can cause heart problems.
Image: Caffeine Powder

Studies have shown that caffeine definitely increases heart rate, and that an increased heart rate leads to other heart problems. There is one other factor that comes into play and cancels out this potentially hazardous fact though. When people use caffeine on a daily basis they begin to build up a tolerance as previously mentioned. Studies have found that once a tolerance to caffeine has developed, the heart no longer races with caffeine. In small doses it can even lower heart rate in nonusers.[8] Bealer even goes as far as saying, “You may be safer drinking coffee every day than you would be doing so once or twice a week.”[1] For every study finding a link between heart problems and caffeine usage, there is a corresponding study that says there is no link. While caffeine has yet to be proven to definitely cause heart problems, at least one study has found it to indirectly affect the heart. Coffee raises homocysteine levels in the blood which have been linked to an elevated risk of heart attacks. Caffeine is known to increase the effects of the other chemicals in coffee that cause this. It is often the other chemicals mixed with caffeine that cause many of the effects blamed on caffeine alone.[9]
    Many studies have tested for caffeine’s effects on pregnancy. One such study looked at 2,714 live births and 135 spontaneous abortions. It found that drinking three or more cups of coffee a day resulted in a raised risk of spontaneous abortions. It also found a higher correlation between caffeine usage and spontaneous abortion than with alcohol or cigarette use.[10] Another study found a statistically significant correlation between pregnant women drinking eight cups of coffee a days and birth defects in children. Despite this, the researchers said, “The data presented does not permit us to conclude a direct relation between coffee consumption and birth defects.”[11] Despite these fairly disturbing results, there are many studies that find no connection at all. This has led the Institute of Medicine to say, “No adverse effect on reproduction [. . .] has been linked consistently to caffeine consumption.”[3] They do warn that pregnant mothers should still cut back on caffeine intake as it does cross the placenta into the fetus and is also secreted in breast milk.

Alternatives to Caffeine

    Many commonly abused drugs work in a similar fashion to caffeine on the human body. In the Institute of Medicine's report on caffeine for military operations, they list several alternatives that have similar arousing effects as caffeine. One is amphetamines, which are a central nervous system stimulant just like caffeine. Amphetamines are absorbed about four times slower than caffeine, but help reduce fatigue and “increase feelings of vigor.”[3] They also suggest Pemoline, another central nervous system stimulant, and Modafinil, a drug originally designed to treat narcolepsy.[3] Despite these drug alternatives, the first solution that the Institute of Medicine has for another way to increase energy and alertness without caffeine is to take naps. They even say that as little as fifteen minutes of sleep helps troops. Naps are effective both before and during periods of sleep deprivation. When normal sleep is not possible for troops, the institute suggests both naps and caffeine be administered for maximum effectiveness.[3]
    The use of caffeinated products by the public is unlikely to cease. Since the earliest times, mankind has used this drug to improve stamina, concentration, and reduce tiredness. The intake of this drug has drastically increased over the years leading to many studies concerned with the long term effects of such heavy usage. There is little definitive proof of the lasting effects of caffeine on a healthy person, but it definitely effects the body just as any other drug. It is important for each individual to know how their body handles this drug. Individuals should also be aware of the addictive nature of caffeine and the potential risks involved in heavy usage.

Articles are never complete. Feel free to make modifications or additions as needed.

References

  1. Weinberg, Bennett A., and Bonnie K. Bealer. The World of Caffeine. New York: Routledge, 2001.
  2. Smith, Barry D., Thom White, and Rachel Shapiro. "The Arousal Drug of Choice: Sources and Consumption of Caffeine." Caffeine and Activation Theory: Effects on Health and Behavior. Ed. Barry D. Smith, Uma Gupta, and B S. Gupta. Boca Raton: CRC Press, 2007. 9-40.
  3. Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations. Institute of Medicine. Washington, DC: National Academy Press, 2001.
  4. Fisone, G, A. Borgkvist, & A. Usiello. (2004). “Caffeine as a psychomotor stimulant: mechanism of action.” Cellular and Molecular Life Sciences, 61.7: 857-72.
  5. Nehlig, Astrid. "Pharmacological Properties and Neurophsysiological Effects of Caffeine." Caffeine and Activation Theory: Effects on Health and Behavior. Ed. Barry D. Smith, Uma Gupta, and B S. Gupta. Boca Raton: CRC Press, 2007. 43-60.
  6. "Erowid Caffeine Vault." Erowid. 9 Feb. 2008. 14 Feb. 2008
    http://www.erowid.org/chemicals/caffeine/caffeine.shtml
  7. Iancu, Julian, Ahikam Olmer, and Rael D. Strous. "Caffeinism: History, Clinical Features, Diagnosis, and Treatment." Caffeine and Activation Theory: Effects on Health and Behavior. Ed. Barry D. Smith, Uma Gupta, and B S. Gupta. Boca Raton: CRC Press, 2007. 241-243.
  8. Smith, Barry D. and Katherine Aldridge. "Acute Cardiovascular Effects of Caffeine: Hemodynamics and Heart Function." Caffeine and Activation Theory: Effects on Health and Behavior. Ed. Barry D. Smith, Uma Gupta, and B S. Gupta. Boca Raton: CRC Press, 2007. 82-83.
  9. Harder, B. “Coffee Jitters.” Science News, 163.1 (2003): 5.
  10. Dlugosz, L, Belanger, K, Hellenbrand, K. “Maternal Caffeine Consumption and Spontaneous Abortion: A Prospective Cohort Study.” Epidemiology, 7.3 (1996): 250-255.
  11. Lechat, MF, Borlee, I, Bouckaert, A, et al. “Caffeine Study.” Science, 207 (1980), 1296-7.

Comments

Really Very Informative Knol

Hey William,

I am also one of addict to coffee, after reading your knol, i really need to control my habit.
thanks for such informatine knol.

Last edited Feb 2, 2009 11:18 PM
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Great info for a coffee lover

Hi William,

I'm a coffee lover and reading your knol inspire me to limit my daily intake of caffeine :)

I blogged on your knol at my blog-mag Knol Today - http://www.knoltoday.com/health/2008/10/17/all-about-caffeine/

Cheers! :)

Last edited Oct 18, 2008 5:31 PM
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Well done

I've seen plenty of articles on knol (I'm an addicted Knolian), but this one is of the highest quality. Easy read, informative, complete, concise, credible.

I also like that you welcome feedback.

Last edited Sep 26, 2008 5:28 PM
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Awesome Article

The most informative I’ve found in searching for a couple of hours. Answered many of my questions that other articles failed to explain.

Last edited Sep 10, 2008 8:54 PM
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William Wynn
William Wynn
Student at UCSB
Santa Barbara, CA
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