The World’s Psychoactive Drug of Choice

By MIKE MAGEE

Question: What is the world’s most widely used psychoactive drug?

Answer: Caffeine

In the U.S., caffeine is consumed mainly in the form of coffee, tea, and cola. But coffee dominates. Worldwide, humans consume over 10 million tons of coffee beans a year. Roughly 16% (1.62 million tons) is devoured by Americans. The daily intake of caffeine varies depending on type of beverage and brand as the chart below indicates. 

On average, each American consumes approximately 164 mg of caffeine each day. That’s roughly 1 small cup of Dunkin or (3.5) 12-ounce Diet Cokes (Trump consumes at least 12 cans of Diet Coke a day). 

Across the globe, daily consumption of caffeine is close to universal. Eight in 10 humans consume a caffeinated beverage daily. That makes this chemical substance the “most commonly consumed psychoactive substance globally.” Its popularity is related to its ability to deliver three useful physiological enhancements – wakefulness, motor performance, and cognition.

Chemically, caffeine is a close cousin of adenosine which is present in brain neurons. Adenosine builds up in synaptic connections between brain neurons. When it binds to special receptors, it activates neurons that promote sleepfulness. Ingested caffeine is water and lipid soluble, and therefore is able to traverse the blood-brain barrier. Once inside, its chemical structure mimics that of adenosine, and it occupies adenosine receptors because it shares the same approximate shape and size. When these receptors are occupied by caffeine, adenosine molecules are unable to activate the receptors. The net effect is wakefulness.

Caffeine passes thru small intestine cell walls and is absorbed within 45 minutes of ingestion. From there, it is distributed to all bodily cells reaching highest concentrations within 1-2 hours. The average time required to remove 1/2 of a caffeine dose (the half-life) is 3 to 7 hours. Thereafter it is broken down in the liver. 

Over 30 plants species naturally produce caffeine. The most common source of caffeine are the seeds or beans of two coffee plants ( Coffee arabica and Coffee canephora), the leaves of tea plants, the seeds of the cocoa plant (Theobroma cacao) used in chocolate production, and kola nuts (used to produce Cola beverages). 

For chocolate lovers, caffeine levels depend on the product. A 4 ounce bar of dark chocolate has approximately 80 mg of caffeine. Night time ingesters may do better with milk chocolate which contains 24 mg in 4 ounces. 

Pure solid caffeine is bitter, odorless, and melts at 235 degrees C. The 60’s generation were familiar with various tablet forms  like No-Doz (Bristol-Myers Squibb) and Vivarin (SmithKline Beecham). Each tablet contained 100 mg of caffeine. The U.S. market is estimated at $60 million annually. The three top consumer markets are college students (for “all-nighters”), truck drivers and body builders. 

None of this is especially breaking news. The restorative powers of boiling tea leaves was first documented in 3000 BC. The Cocoa bean was harvested by Mayans in 600 BC. Coffee use is more recent, with first accounts in the Middle East in the 15th century. Three centuries later, French chemists isolated the active ingredients, with the term Caféine first appearing in the French scientific literature in 1822. 

Back in 1911, Trump may have run into a problem ingesting 10 Cokes a day. Public officials viewed the product (and its stimulants) with suspicion. In fact, their seizure of 20 kegs of Coca-Cola syrup in Chattanooga, TN, led to the landmark case, United States v. Forty Barrels and Twenty Kegs of Coca-Cola. The company prevailed only to have the U.S. Congress pass a law the following year requiring that the company include the phrase “habit-forming” on their label. 

These days, caffeine consumption varies with age and sex –  “2 mg/kg/day in children, 2.4 mg/kg/day in women, and 2.0 mg/kg/day in men.” As for caffeine powder tablets, they remain unregulated. Reading between the lines, experts are preaching caution a bit more often, as in this government summary in 2017: 

“When taken together, the literature reviewed here suggests that ingested caffeine is relatively safe at doses typically found in commercially available foods and beverages. There are some trends in caffeine consumption, such as alcohol-mixed energy drinks, that may increase risk of harm. There are also some populations, such as pregnant women, children, and individuals with mental illness, who may also be considered vulnerable for harmful effects of caffeine. Excess caffeine consumption is increasingly being recognized by health-care professionals and by regulatory agencies as potentially harmful.”

Mike Magee MD is a Medical Historian and regular contributor to THCB. He is the author of CODE BLUE: Inside America’s Medical Industrial Complex. (Grove/2020)