Episode notes
The molecule in your morning cup evolved as a pesticide. More than 60 plant species, including coffee, tea, yerba mate, and cacao, arrived at caffeine independently because it paralyzes and kills the insects that chew on them. Fallen coffee leaves leach it into the soil to stop rival seeds from germinating, while trace amounts in nectar give bees a dopamine hit that makes them return. German chemist Friedlieb Ferdinand Runge first isolated the pure compound from Arabian mocha beans in 1819, and humanity now consumes about 120,000 tons of it a year. The episode explains the adenosine blockade behind the buzz and the tolerance trap where a morning cup mostly reverses yesterday's withdrawal.
Then the story gets stranger. In 1911 the United States government seized 40 barrels and 20 kegs of Coca-Cola syrup from a train in Chattanooga, Tennessee, alleging caffeine was a poisonous and deleterious ingredient. Today caffeine citrate is on the World Health Organization's list of essential medicines and keeps premature babies breathing. Most pure caffeine powder in sodas and energy drinks is synthesized in labs, largely in China, from urea and chloroacetic acid, and scientists tell it apart from plant caffeine by its carbon isotope signature. The natural supply comes from German decaffeination plants, which sell caffeine stripped from decaf beans to drink makers.
- Adding about 100 to 130 milligrams of caffeine to painkillers like ibuprofen or paracetamol speeds absorption and improves relief.
- Athletes use about five milligrams per kilogram of body weight, but performance follows an inverted U curve at high doses.
- L-theanine in tea promotes alpha brain waves and smooths out caffeine's jittery edge.
- During late pregnancy, caffeine's half-life stretches from a few hours to about 15 hours as the CYP1A2 enzyme is suppressed.
- One tablespoon of pure caffeine powder equals roughly 50 cups of coffee, enough to trigger cardiac arrest.