Gustav III of Sweden's coffee experiment

[1] The primitive medical study, supposedly conducted in the second half of the 18th century, failed to prove that coffee was a dangerous beverage.

[5] Both Gustav III and his father had read and been strongly influenced by a 1715 treatise from a French physician on the dangers of what would later be identified as caffeine in tea and coffee.

To this end he ordered a scientific experiment to be carried out in what has been loosely referred to as the first randomized controlled clinical trial.

[7] The tea drinking twin died first at the age of 83, long after the death of Gustav III, who was assassinated in 1792.

The age of the coffee-drinking twin at his death is unknown, as both doctors assigned by the king to monitor this study predeceased him.