In 2399, Jean-Luc Picard finally switched to decaf
Decaffeination was the process of removing caffeine from food and beverages containing the stimulant. Decaffeinated products were commonly termed decaffeinated or simply decaf.
On December 27 2000, Henry Janeway served Shannon O'Donnel a cup of "decaf" coffee, which he described as "Not exactly the nectar of the gods." O'Donnell accepted it gratefully just the same. (VOY: "11:59")
When asked to create a decaffeinated raktajino in 2373, Quark claimed that "the removal of caffeine from beverages has plagued bartenders and restauranteurs for centuries! You can't expect me to solve it overnight!" Quark made this claim following his failed attempt to help get Major Kira off caffeine during her pregnancy with Miles and Keiko O'Brien's son. According to Chief O'Brien, he didn't want his son "to be born with a caffeine habit." (DS9: "Nor the Battle to the Strong")