1788: Born in Fairfield, Connecticut, on November 7, 1788. Jennings worked on his father’s farm during his youth.

1805: He married Maria, daughter of Deacon Nathan Beers, on Sept. 17, 1805, and had three sons and two daughters.

1808: Jennings entered and studied in the office of Eli Ives, M.D. (New Haven and Yale), and “read medicine” as was the custom from 1809 to 1811.

1812: Graduated from Yale and was licensed to practice medicine.

1820: Jennings, M.D. moved his practice from Trumball to Derby, CT. 

1822: The beginning of health care based on physiology, or Natural Hygiene, started with Isaac Jennings, M.D.

• Jennings discontinued all use of drugs on his patients.
• Began the use of fasting.
  • Sylvester Graham is quoted in The Greatest Health Discovery, “Fasting removes those substances which are of the least use to the economy, and hence, all morbid accumulations, such as wens, tumors, abscesses and so on, are rapidly diminished and wholly removed by abstinence and fasting.” 

1828: He received his M.D. from the Yale School of Medicine

1830: Sylvester Graham‘s lectures and writings launched the crusade for health and “physiological reform” of the people.

1839: Jennings moved to Oberlin, Ohio. The town was designed as a health-promoting model colony and later developed into the Seventh-day Adventist Church. He became a member of the Board of Trustees of Oberlin College and served as the city mayor. 

1847: Wrote his book Medical Reform: a Treatise on Man’s Physical Being and Disorders: Embracing an Outline of a Theory of Human Life, and a Theory of Disease, its Nature, Cause, and Remedy.

1852: Wrote his book The Philosophy of Human Life. 

1853: Named Professor Emeritus at Yale. 

1860: the American Medical Association (in New Haven) elected him President.

1867: Wrote the book The Tree of Life: or Human Degeneracy, its Nature and Remedy: Based on the Elevating Principle of Orthopathy. Nature is always upright—moving in the right direction. 

1867: (Wikipedia) The Buffalo Medical and Surgical Journal described Jennings’ methods of utilizing bread pills as “downright quackery and imposition” and a “disgrace to the regular profession.” A review of his book The Tree of Life suggested it was “without a particle of merit,” and the ideas would not be popular with people of the present day.

1874: In Oberlin, Ohio, on March 13, 1874, Jennings died of pneumonia.