Coffee seems to have had a love/hate relationship with royalty.

For centuries, many people viewed the caffeinated beverage with suspicion. Around the year 1600, many in Roman Catholic circles viewed coffee as evil, prompting Pope Clement VIII’s advisors to urge him to denounce the drink. Fortunately for coffee lovers, the pontiff refused to opine on the matter until he had tried it for himself. Upon tasting his first cup of coffee, he is reported to have said, “Why, this Satan’s drink is so delicious that it would be a pity to let the infidels have exclusive use of it.” Thereupon, he gave coffee his official blessing, clearing the way for the faithful to enjoy the delicious drink without fear of losing their souls.

Not all monarchs were as easy to persuade.

Sweden’s Gustav III (1746-1792) was not a coffee aficionado by any means. His dislike for the drink had less to do with concerns about theology and more to do with health. He was firmly convinced that coffee was a hazardous substance and was determined to prove his suspicions with hard science.

The king authorized what may have been the first clinical trials concerning coffee’s potential detriment to human health. To do this, he needed a couple of test subjects. He found them in the form of two twin brothers who had been sentenced to death for their crimes. The king offered to commute their sentences to life imprisonment if they would agree to participate in his experiment. They both agreed.

The brothers had to agree to do something for the rest of their lives. One of them had to drink three pots of coffee each day. The other had to drink an equal amount of tea. The king was confident that the coffee drinker would quickly succumb to the toxic brew, thus proving his theory.

You will have already guessed that Gustav’s concerns were misplaced. The life expectancy of a male born in 1750 in Sweden was 33.72 years (source). The first of the twins to die was the tea drinker, who lived to the ripe old age of 83 years. Unfortunately, the king did not get to see the outcome of his experiment. He was assassinated at the age of 46 years. The record is silent as to whether the assassin was a coffee drinker.

In verifying the authenticity of Gustav’s coffee experiments, several accounts, such as this one, note that the authenticity of the story is disputed. Nowhere have we been able to find the purported disputer. Given that we live in a world where people organize around disputing such irrefutable facts as the earth being round, Finland being a real place, or that pineapples have no business being anywhere near a pizza, we’re not overly impressed by the simple notation “the authenticity of this is disputed.” In the interest of accuracy, however, we did track the story to the Cultural Heritage Group of the Uppsala University Library. It reports Gustav’s coffee trials without any concerns about authenticity. Since Uppsala University is the oldest university in Sweden (founded in 1477), we’re inclined to give them the benefit of the doubt.

Although Gustav did not live long enough to see the error of his ways concerning coffee condemnation, Swedes today are grateful that the drink is not the dangerous thing their former king thought it was. Today, Swedes are the 6th-highest coffee consumers in the world, going through the stuff at the rate of 18 pounds (8.1 kg) per person each year.