According to Encyclopædia Britannica, his "development of dry breakfast cereals was largely responsible for the creation of the flaked-cereal industry, with the founding and the culmination of the global conglomeration brand of Kellogg's (now Kellanova).

[7][8] Kellogg held liberal theological beliefs radically different from mainstream Nicene Christianity and emphasized what he saw as the importance of human reason over many aspects of traditional doctrinal authority.

He strongly rejected fundamentalist and conservative notions of original sin, human depravity, and the atonement of Jesus, viewing the last in terms of "his exemplary life" on Earth rather than death.

At the Seventeenth Annual Session of the General Conference of Seventh-day Adventists, October 4, 1878, the following action was taken:WHEREAS, The impression has gone out from some unknown cause that J. H. Kellogg, M.D., holds infidel sentiments, which does him great injustice, and also endangers his influence as physician-in-chief of the Sanitarium; therefore

RESOLVED, That in our opinion justice to the doctor and the Institute under his medical charge, demand that he should have the privilege of making his sentiments known, and that he be invited to address those assembled on this ground, upon the harmony of science and the Sacred Scriptures.

– In accordance with the foregoing resolution, Dr. Kellogg gave, before a large audience, October 6, an able address on the harmony of science and the Bible, for which the congregation tendered him a vote of thanks.

It is the divine will that causes it to beat, and in the beating of that heart that you can feel, as you put your hand upon the breast, or as you put your finger against the pulse, an evidence of the divine presence that we have within us, that God is within, that there is an intelligence, a power, a will within, that is commanding the functions of our bodies and controlling them…[24] He further elaborated these ideas in his book The Living Temple (1903): There is a clear, complete, satisfactory explanation of the most subtle, the most marvelous phenomena of nature, – namely, an infinite Intelligence working out its purposes.

[27] Tensions came to a head when the Battle Creek Sanitarium, originally owned by the Seventh-day Adventist Church but run by Kellogg, was destroyed by fire on February 18, 1902.

[28] Ellen G. White, who had proclaimed that a cleansing sword of fire was poised over the increasingly "worldly" and business-oriented Battle Creek, was against rebuilding the large institution.

Kellogg retained control of the Battle Creek Sanitarium and the American Medical Missionary College, and continued to promote Adventist ideas of health and well-being at those institutions.

[46] He had many notable patients, such as former president William Howard Taft, composer and pianist Percy Grainger, arctic explorers Vilhjalmur Stefansson and Roald Amundsen, world travellers Richard Halliburton and Lowell Thomas, aviator Amelia Earhart, economist Irving Fisher, Nobel prize winning playwright George Bernard Shaw, actor and athlete Johnny Weissmuller, founder of the Ford Motor Company Henry Ford, inventor Thomas Edison,[47] African-American activist Sojourner Truth, and actress Sarah Bernhardt.

In this, Kellogg followed the teachings of Ellen G. White and Sylvester Graham who recommended a diet of bland foods to minimize excitement, sexual arousal, and masturbation.

The process described involved taking raw edible nuts, preferably peanuts or almonds, blanching them to remove their skins, and then boiling them for several hours.

The nuts were then crushed and passed through rollers to separate out "a fine and comparatively dry and nearly white nutmeal" and a "moist, pasty, adhesive, and brown" butter or paste.

[69] On March 19, 1901, Kellogg was granted the first United States Patent for a "vegetable substitute for meat", for a blend of nuts and grain cereals called "Protose".

[71] Although they are less discussed than his food creations, Kellogg designed and improved upon a number of medical devices that were regularly used at the Battle Creek Sanitarium in surgical operations and in treatment modalities falling under the term "physiotherapy".

[32] Dr. Kellogg attempted to popularize these treatment methods, including electrotherapy, hydrotherapy, and motor therapy, in his work The Home Handbook of Domestic Hygiene and Rational Medicine, first published in 1881.

[75] It was spread to Vienna by Kellogg's friend Dr. Wilhelm Winternitz; installed in royal palaces across Europe; and popularly replaced old Turkish steam baths at athletic clubs.

In order "to make a record of his work and experience as a pioneer in this branch of physiotherapeutics", Kellogg published his book Light Therapeutics: a practical manual of phototherapy for the student and the practitioner, with special reference to the incandescent electric-light bath in 1910.

[76] In the short work, Kellogg describes the application of the arc light to the spine, chest, abdominal region, loins, shoulders, hip and thigh, knees and other joints.

"[78] As a result, electrotherapy coils were used in the Static Electrical Department of the Battle Creek Sanitarium especially for cases of paresthesias of neurasthenia, insomnia, and certain forms of neuralgia.

Vibrational therapy by way of sinusoidal (high-frequency oscillating) electric current was discovered by Kellogg in 1884 to have medical use for increasing blood circulation and passive exercise.

[79] Furthermore, Kellogg devised an electrotherapy exercise bed in which a sinusoidal current that produced muscular contraction could be delivered without pain for twenty minutes and reportedly achieve the stimulation of a brisk four-mile walk.

As such, the policies and therapies at the Battle Creek Sanitarium were very much in line with these principles of biologic living, such as the focus on vegetarianism or drinking 8–10 glasses of water a day.

[16]: 91  In terms of practice, Kellogg's biologic living was very similar to the methods of Christian physiologists, requiring sexual restraint, total abstinence from drugs, and a vegetarian diet.

[16]: 107  Kellogg's work on several committees against smoking culminated in Utah Senator Reed Smoot introducing a bill to Congress in 1929 that aimed to put tobacco under the purview of the Pure Food and Drug Act.

Kellogg's view was that "nature has supplied us with pure water, with a great variety of fruit juices and wholesome and harmless flavors quite sufficient to meet all our needs.

In his opinion, this prejudicial approach to illness resulted in converting hydropathy to a more heroic type of treatment where many became obsessed with taking baths in ice-cold water.

Kellogg was in favor of racial segregation in the United States and he also believed that immigrants and non-whites would damage the white American population's gene pool.

[111] The adopted children included Agnes Grace, Elizabeth Ella, Harriett Eleanor, John William, Ivaline Maud, Paul Alfred, Robert Mofatt, and Newell Carey.