The history and use of caffeine and its effect on the human body.
Caffeine has been used as a drug for thousands of years. The use of caffeine has gradually shifted from medical to recreational applications. There are several plants that contain the substance that were cultivated or harvested, but today caffeine is added to many foods. Despite the increase in caffeine use in recent times, many people have little knowledge of the overall effects it has on their bodies.
Plants that contained caffeine have been used as a stimulant and source of energy since as they were discovered. Different cultures all around the world used caffeine 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.
The poet Johann Wolfgang von Goethe gave Runge some 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 kola nuts.
History of Caffeine
The oldest sources of caffeine that are commonly used today are tea, chocolate, coffee, and 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. Ancient writings detail 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.
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.
Despite being the current primary source of caffeine, coffee did not make its appearance until the ninth century in Ethiopia and possibly not until the fifteenth century in southern Arabia. This late discovery of coffee is unusual since coffee grew along trade routes between Ethiopia, Abyssinia, and the Middle East. Unlike chocolate and tea, coffee beans were 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.
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 kola nuts. While the kola 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.
Increase in Caffeine Usage
Caffeine has become the easiest drug to get a hold of, and is now used by most adult Americans every day.
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. By 1997 the average person drank 53 gallons per year. Energy drinks were developed much later than soft drinks and did not become largely popular until fairly recently.
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.
Moderate Levels of Caffeine
Caffeine is rapidly absorbed into the bloodstream by the body after oral ingestion. Its levels in the body can peak in as little as fifteen minutes and then are completely absorbed in just forty-five minutes. The most common way to take caffeine is orally. Caffeine affects the central nervous system travelling through 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.
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.
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 energy that people associate with caffeine comes from the fact that caffeine is a stimulant. Pure caffeine is extremely toxic to humans. The chemical cannot be touched with bare hands and the fumes cannot be inhaled without serious effects.
Warnings include “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.”
Low doses of caffeine appear to increase motor coordination, while higher amounts decrease it to below normal levels. 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. 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. 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. There is a correlation between increased caffeine intake and decreased depression, but it has yet to be proven to cause it. An increased intake of caffeine also increases a person’s willingness to accept alternative ideas as well as raises performance levels on repetitive tasks. It is important to note that these are reactions from intake of low to moderate levels of caffeine (20mg to 400mg).
High 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. Complete tolerance to caffeine's effects can develop very quickly in a matter of weeks. 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.
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. It is estimated that the lethal dose for humans is between 150 mg/kg and 200 mg/kg but varies depending upon individual and sensitivity.
Scientists have been examining whether excessive caffeine intake can cause heart problems.
Studies have shown that caffeine 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. 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.
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. Individuals should also be aware of the addictive nature of caffeine and the potential risks involved in heavy usage.