Caffeine, caffeine or tein is a xanthine alkaloid with stimulant, psychoactive effects. Caffeine has a stimulating effect in humans. In its pure form, the white, odorless powder was first extracted from coffee beans in 1820 and has a bitter taste. Caffeine occurs naturally in various plants and there in different parts of the plant. It has the effect of a natural pesticide, as it paralyzes or even kills certain pests that attack the plant. Caffeine is found in certain foods and stimulants, such as coffee, tea, guarana, maté or cocoa. Pure caffeine can be extracted from plants for further use or produced synthetically.
Medical effect and application
Caffeine is found in certain foods and beverages, such as coffee, tea, guarana, maté, or cocoa. Pure caffeine can be extracted from plants for further use or produced synthetically. Caffeine is probably the most commonly consumed psychoactive substance worldwide. It has a stimulating effect on metabolism and the central nervous system. Its effect in the body is complex and leads to increased alertness, concentration, body coordination and alertness. It also lightens the mood. Caffeine from drinks is absorbed after 45 minutes with a peak of concentration in the blood after one hour. In addition, caffeine can be taken as a tablet or suppository. In healthy adults and without further medication, half of the caffeine has been broken down by the liver after about five hours. Caffeine easily crosses the blood–brain barrier and therefore acts directly on the brain and nervous system. In moderate doses, for example two cups of coffee daily, caffeine has some positive effects on the body. For example, a 2010 study shows that shift workers who consume caffeine make fewer mistakes and suffer fewer injuries. In newborns, caffeine is used to treat apnea, lung problems and irregular heartbeat. Caffeine has a relaxing effect on anal muscles, making bowel movements easier, but should be avoided if incontinence is present. Since caffeine has been shown to reactivate hair follicles in laboratory tests, hair growth shampoos containing caffeine are now available. At least the absorption of caffeine from shampoo has been proven. Whether natural hair growth actually becomes stronger is as yet unproven. Caffeine also enhances the effect of certain painkillers and is therefore a component of some painkillers as well as antihistamine preparations, where it reduces the annoying accompanying symptom of fatigue. In addition, caffeine has been observed to have a liver-protective effect in high-risk groups. However, the underlying mechanism has not yet been researched. Sustained, excessive caffeine consumption can have unpleasant consequences such as nervousness, muscle tremors, anxiety disorders or insomnia, and can lead to dependence. The lethal dose of caffeine in rats is circa 200 mg per kilogram of body weight.
Importance for sports and exercise
Caffeine is also used in sports after numerous studies demonstrated an endurance-enhancing effect of the substance. The University of Illinois was also able to show a slight pain-relieving effect of caffeine. The form in which the substance is administered does not play a role. Quantities of three to six milligrams of caffeine per kilogram of body weight are used. At higher amounts, no further increase in performance is achieved. Anyone who wants to use caffeine specifically during training or competition should avoid caffeine for a few days beforehand, as the body becomes accustomed to the effect of the stimulant. However, there are also statements that caffeine does not improve athletic performance, but actually inhibits it. A study by the University Hospital of Zurich indicates lower blood flow through the heart when caffeine is taken during endurance sports and advises people with cardiovascular problems not to use caffeine during sports.
