Word of Wisdom, Revelation on Health

A decoction is a concentration of those substances that can be leeched from a plant by the action of hot water. Both coffee and tea are decoctions. Some have suggested that it is merely the temperature of such drinks that makes them unhealthy, but that isn't what Joseph Smith, Jr., said.

"The prophet, when applied to for information upon the subject, said that tea, coffee, and etc. were expressly forbidden by the "Word of Wisdom", not only because they were usually taken hot, but because they were decoctions which in their very nature were destructive to health." - Millenial Star, No. 1, Volume XIV, January 15, 1852, pg.32

It is counter intuitive to believe that all decoctions are destructive to health, as soup itself is a decoction. One must keep in mind the purpose of the decoction. Coffee and Tea are not just popular because they are drinks, but because of their psychotropiceffect on the body and mind.