An Old Anti-Coffee Experiment Saw Everyone But The Coffee Drinker Die

Coffee is bad for you, say a lot of people, because anything that feels good has to be bad for you. Caffeine is a drug, and drugs are bad, right? And so some people, seeking to keep their bodies pure, strip coffee from their diets and plan to live till a hundred.

We don't have any real evidence that drinking coffee shortens your lifespan, and it's possible that the opposite is true, with caffeine appearing to reduce the risks of getting various diseases. This is despite a whole lot of experiments that started out with the idea that coffee is bad for you, including one famous one from back in the 18^th century.

King Gustav III of Sweden taxed coffee heavily and eventually even totally banned it. He believed coffee hurts people, in some ill-defined way, and he commissioned an experiment on two twins to prove this. Each of these men were on death row, and the king commuted their sentences in return for the following demand: One of them must drink three pots of coffee every day for the rest of his life, while the other would drink tea. The tea drinker, hypothesized the king, would long outlive the coffee drinker.

This experiment was ahead of its time in many ways. It largely predated the whole concept of clinical trials. The idea to focus on twins, to exclude any differences due to genetics, was particularly inspired, since this also predated the entire scientific concept of genes (though people have always suspected something like genes exist, based on how we look like our parents). Still, the experiment was doomed never to produce useful data. Even picking twins, it's impossible to control all the many variables that affect lifespan, and no experiment with a sample size this small can tell us much of anything.

The coffee experiment also backfired for a more specific reason: Both the men just lived much longer than expected. The tea drinker turned out to die first, at the age of 83, and we don't even have records of when the coffee drinker died. That's because both twins outlived the doctor conducting the experiment. They outlived the second doctor who was involved as well. And they easily outlived King Gustav, who was assassinated in 1792 while attending a masked ball, which is an activity far more dangerous than drinking any one beverage.

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