Coffee has long been one of the most important threads running through European history. But what many people don’t realize is that coffee also has its own “dark history.” When coffee first arrived in Europe in the late 16th century, it immediately raised alarm within the Christian church. This black beverage from the “infidel” Muslim world was once condemned as “the devil’s drink.”
By the 18th century, this suspicion was still very much alive in Sweden. King Gustav III firmly believed that coffee was harmful to the human body and regarded it as a kind of poison. In order to prove coffee’s dangers, he organized what would later become one of the most infamous human experiments in coffee history. Although the scientific validity of this experiment is highly questionable by modern standards, it nevertheless revealed something remarkable: as early as the 18th century, humans had already discovered that coffee was, in fact, non-toxic.
To understand this story, we first need some historical context. Coffee was introduced to Sweden around 1674. In 1746, the Swedish government issued a royal decree banning the consumption of both tea and coffee. Heavy taxes were imposed on coffee, and those who failed to pay faced fines and confiscation of their cups and utensils. Before long, coffee was completely outlawed.
Of course, people continued drinking it in secret—because let’s be honest, who could resist something that delicious? It wasn’t until the late 18th century that coffee gradually became fashionable again, especially among the wealthy.
During Gustav III’s reign, however, the king remained deeply concerned that coffee posed a serious threat to public health. Determined to prove its harmful effects, he ordered a controlled experiment. Two identical twins who had been sentenced to death were selected as test subjects. Their sentences were commuted to life imprisonment on one condition: one twin would drink three pots of tea every day, while the other would drink three pots of coffee daily for the rest of his life.
To ensure proper observation, the king appointed two physicians to monitor the twins’ health and report regularly to him. In simple terms, everyone was waiting to see who would die first.
Years passed, and both prisoners remained alive and well. In a twist worthy of dark comedy, the two doctors assigned to observe the experiment died before either of the twins. Even more ironically, King Gustav III himself never lived to see the outcome. In 1792, he was assassinated by a disgruntled nobleman at a masquerade ball and died from his wounds. With his death, the experiment lost both its supervisor and its original purpose.
With no king and no doctors left to observe them, the twin brothers continued drinking their assigned beverages in prison. Eventually, the tea-drinking twin passed away first—at the age of 83, an astonishing lifespan by 18th-century standards. The coffee-drinking twin lived even longer, though his exact age at death is unknown. What is certain is that he outlived his brother.
What was intended as proof that coffee was dangerous instead became unintended evidence that coffee was harmless—and perhaps even linked to longevity. The entire story is steeped in black humor and historical irony: everyone who expected coffee to be deadly—the king and the doctors—died first, while the experimental subjects themselves lived long lives.
Gustav III’s experiment was flawed, unethical, and deeply disturbing by modern standards, yet it remains one of the most thought-provoking episodes in coffee history. After coffee bans were eventually lifted, coffee went on to become Sweden’s primary daily beverage, helping the country become one of the highest per-capita coffee consumers in the world.
After hearing this story, doesn’t the coffee in your hand somehow taste even better? Go ahead—take another sip. Here’s to long life and good coffee.
