Doctrine and Covenants Lesson #22
The revelation named the Word of Wisdom was given in 1833 in Kirtland, Ohio. It gives advice on healthy living through care of the body. Devoted Saints began to heed the revelation's counsel immediately, but it was not enforced as a requirement for entering the temple for about a century.
Word of Wisdom
The Word of Wisdom began to be required of people who wanted to enter the holy temple about a century after it was received. How did LDS Church leaders begin to enforce it? It was Brigham Young who set the Church on a course of following the Word of Wisdom to the letter. While most Church members failed to obey the revelation's prescriptions during Brigham's lifetime, he set the goal that members would eventually comply with the Word of Wisdom. During his tenure, he changed the standard from moderate use of tobacco, alcohol, tea, and coffee to full abstinence.
"Tobacco-Related Cancers in Utah Compared to the United States: Quantifying the Benefits of the Word of Wisdom," Ray M. Merrill, Gordon B. Lindsay, Joseph L. Lyon, BYU Studies, Vol. 38, no. 4
This article presents data on tobacco use and incidence of cancer in Utah compared with the United States as a whole. Given that Utah has a high percentage of Mormons who abstain from tobacco, the article shows that living the Word of Wisdom has been beneficial to members of the Church.
The promises associated with the Word of Wisdom are considered both temporal and spiritual. The temporal promise has been interpreted as better health, and the spiritual promise as a closer relationship to God. These promises reflect the concern of the Church with both the temporal and spiritual Welfare of its members.
This page gives a nice overview of how implementation of the Word of Wisdom changed over time, with quotes from Church leaders.