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1,3,7-Trimethyl-9H-purine-2,6,8-trione, more commonly known as caffeine, is a central nervous system (CNS) stimulant of the methylxanthine class. It is the world's most widely consumed psychoactive drug. Unlike many other psychoactive substances, it is legal and unregulated in nearly all parts of the world. Caffeine helps to ward off drowsiness and restore alertness. Beverages containing caffeine, such as coffee, tea, soft drinks, and energy drinks, enjoy popularity worldwide.

Chemical Properties[edit | edit source]

Caffeine is a bitter, white crystalline purine, a methylxanthine alkaloid, and is chemically related to the adenine and guanine bases of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). It is synthesized in plants where it acts as a natural pesticide. It is found in the seeds, nuts, or leaves of a number of plants native to Africa, East Asia, and South America, and helps to protect them against predator insects and to prevent germination of nearby seeds.

Mechanism of Action[edit | edit source]

The primary mode of action of caffeine is as an antagonist of adenosine receptors in the brain. Adenosine is a neurotransmitter that promotes sleep and relaxation by slowing down nerve activity. Caffeine binds to these receptors without activating them, effectively blocking the action of adenosine, leading to increased neuronal activity and the release of other neurotransmitters like dopamine and norepinephrine. This action not only stimulates the CNS but can enhance physical performance and endurance, making it a popular substance among athletes.

Health Effects[edit | edit source]

Caffeine consumption is generally considered safe for most adults in moderate amounts. However, excessive intake can lead to negative health effects, including insomnia, nervousness, restlessness, stomach irritation, nausea, and increased heart rate and respiration. Individuals with certain medical conditions or those who are pregnant are advised to limit their caffeine intake.

Regulation and Culture[edit | edit source]

Caffeine's legal status and cultural acceptance vary significantly around the world. In many cultures, caffeine is consumed daily, and beverages containing it are often used for social gatherings. Despite its widespread use, there have been debates about its health implications and whether it should be more strictly regulated.

See Also[edit | edit source]


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Contributors: Prab R. Tumpati, MD