Why can't Latter-day Saints drink coffee?

1. A WORD OF WISDOM, for the benefit of the council of high priests, assembled in Kirtland, and the church, and also the saints in Zion— 2. To be sent greeting; not by commandment or constraint, but by revelation and the word of wisdom, showing forth the order and will of God in the temporal salvation of all saints in the last days— 3. Given for a principle with promise, adapted to the capacity of the weak and the weakest of all saints, who are or can be called saints. 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. 14. All grain is ordained for the use of man and of beasts, to be the staff of life, not only for man but for the beasts of the field, and the fowls of heaven, and all wild animals that run or creep on the earth; 15. And these hath God made for the use of man only in times of famine and excess of hunger. 16. All grain is good for the food of man; as also the fruit of the vine; that which yieldeth fruit, whether in the ground or above the ground— 17. Nevertheless, wheat for man, and corn for the ox, and oats for the horse, and rye for the fowls and for swine, and for all beasts of the field, and barley for all useful animals, and for mild drinks, as also other grain.

And again, hot drinks are not for the body or belly.

The book claims that Latter-day Saints are cautioned against the use of "caffeine-bearing drinks, such as Coca-Cola."

For the next two generations, Church leaders taught the Word of Wisdom as a command from God, but they tolerated a variety of viewpoints on how strictly this commandment should be observed. Many Saints continued to drink coffee and tea, and some chewed tobacco. In territorial Utah, Church leaders denounced public intoxication and whiskey drinking but were often silent on the moderate use of milder alcoholic drinks. This tolerance gave the Saints time to develop their own tradition of abstinence from habit-forming substances.

The status of the Word of Wisdom in the late 1890s seems evident from contemporary sources. At a meeting on May 5, 1898, the First Presidency and Twelve discussed the Word of Wisdom. One member read from the twelfth volume of the Journal of Discourses a statement by Brigham Young that the Word of Wisdom was a commandment of God. Lorenzo Snow, then the president of the Quorum of the Twelve, agreed, saying that he believe the Word of Wisdom was a commandment and that it should be carried out to the letter. In doing so, he said, members should be taught to refrain from eating meat except in dire necessity, particularly since Joseph Smith taught that animals have spirits. Wilford Woodruff, then president of the Church, said he looked upon the Word of Wisdom as a commandment and that all members should observe it, but for the present, he said, Church leaders should take no definite action except that members should be taught to refrain from eating meat. The minutes of the meeting record that "President Woodruff said he regarded the Word of Wisdom in its entirety as given of the Lord of the Latter-day Saints to observe, but he did not think that Bishops should withhold recommends from persons who did not adhere strictly to it." Though it seems clear that some Church leaders like Heber J. Grant and Joseph F. Smith insisted upon complete abstinence from tea, coffee, liquor, and tobacco, all general authorities did not agree. During a discussion in 1900 after he became president of the Church, Lorenzo Snow again emphasized the centrality of not eating meat, and in 1901 John Henry Smith and Brigham Young Jr. of the Twelve thought that the Church ought not interdict beer, or at least not Danish beer. Other apostles like Anthon H. Lund and Matthias F. Cowley enjoyed Danish beer and currant wine. Charles W. Penrose occasionally served wine. Emmeline B. Wells, then a member of the presidency and later president of the Relief Society, drank an occasional cup of coffee, and George Albert Smith took brandy for medical reasons. Elder George Teasdale agreed with President Woodruff and thought that no one ought to be kept from working in the Sunday School because he drank tea and that eating pork was a more serious problem than drinking tea or coffee.