One bizarre teachings of Mormonism is the so-called "Word of Wisdom" which was a revelation that Joseph Smith received and recorded in the Doctrine & Covenants, section #89. This is considered inspired Scripture to Mormons, and all good Mormons today follow the "Word of Wisdom". The heart of the text is as follows:
4 Behold, verily, thus saith the Lord unto you: In consequence of evils and designs which do and will exist in the hearts of conspiring men in the last days, I have warned you, and forewarn you, by giving unto you this word of wisdom by revelation—
5 That inasmuch as any man drinketh wine or strong drink among you, behold it is not good, neither meet in the sight of your Father, only in assembling yourselves together to offer up your sacraments before him. 6 And, behold, this should be wine, yea, pure wine of the grape of the vine, of your own make.
7 And, again, strong drinks are not for the belly, but for the washing of your bodies. 8 And again, tobacco is not for the body, neither for the belly, and is not good for man, but is an herb for bruises and all sick cattle, to be used with judgment and skill. 9 And again, hot drinks are not for the body or belly.
10 And again, verily I say unto you, all wholesome herbs God hath ordained for the constitution, nature, and use of man— 11 Every herb in the season thereof, and every fruit in the season thereof; all these to be used with prudence and thanksgiving.
12 Yea, flesh also of beasts and of the fowls of the air, I, the Lord, have ordained for the use of man with thanksgiving; nevertheless they are to be used sparingly; 13 And it is pleasing unto me that they should not be used, only in times of winter, or of cold, or famine.
This "divine revelation" is the reason why Mormons don't drink alcohol, coffee, or smoke tobacco. This is the extent of what most good Mormons know and are encouraged to follow in regards to this Word of Wisodom. But the person who reads the entire section (particularly the parts I highlighted in red) will see that there is more to the Word of Wisdom than what most Mormons care to follow - despite the fact God is allegedly giving these commands.
Notice how the text plainly says only those fruits and herbs in season should be used, meaning all canned fruits and packaged herbs are technically forbidden. And the same is true for meats, which in this case man is commanded to use "sparingly," namely only in times of winter or famine. What Mormons do you know of who follow this teaching? I don't know of a single one, nor have I ever heard them write or speak on these 'forgotten' parts of the Word of Wisdom.
To add to this confusion, Mormons have said caffeine is included in these prohibitions, yet I see nothing in these prohibitions indicating that. While "hot drinks" most likely does refer to coffee, I don't see why this also wouldn't exclude hot tea, hot milk, hot cider, etc, nor would it exclude 'cold drinks' with caffeine like sodas. Another interesting oddity is that in verse 17b it says "mild drinks" that are grain based are allowed, which logically would allow some mildly alcoholic beers, yet Mormons shun these as any other alcohol. There doesn't seem to be any objective standard to judge this.
As a tangential note to all this, despite the fact the Word of Wisdom clearly says wine can be used for the Communion service (v5b), the LDS have officially abandoned even this, and now exclusively use water instead of wine for their worship service. Note what the LDS site that welcomes seekers even says: "We partake of the sacrament (communion), which consists of prepared bread and water, blessed and passed to members of the congregation by priesthood holders." This is because another of Smith's revelations in 1830 (Doctrine & Covenants, section 27) states God doesn't care what elements one uses for Communion, what matters is the heart and intent when partaking. This means one can use anything from pizza and milk to cookies and water. This only feeds into the Mormon 'fear' of alcohol, again despite the fact Smith officially taught it was ok.
So the question is, are the Mormons really being wise about their own teaching? Does the Wisdom of God include picking and choosing what commands and advice to obey or ignore? I would say the answer to both of those questions is "No". This is aside from the fact the Bible nowhere forbids these things or puts such restrictions, aside from the commands to avoid gluttony and drunkenness. That Mormons would even put this kind of teaching forward as something necessary to be saved or be a good person in God's sight is more foolishness than wisdom.
P.S. This post has nothing to do with the health benefits of avoiding tobacco or alcohol, but rather whether such words really came from God and whether Mormons are actually obeying God's commands.