The Battle Creek Sanitarium was run for people not just the terminal, nor for the mentally ill, but for average people to become healthy, by using new, and holistic means. Use of repeated enemas, scientific diets, and various means to control one's sex drive, including married people were designed to create a means for the patients to overcome their own weakness and become healthier than before they were sick. The head of the sanitarium was a doctor of medicine, John Harvey Kellogg believed the human body would mend its own wounds, become healthy, and would live far beyond the typical lifespan of the day. And he demonstrated that by dying at the old age of 91 years old.
However, as happens when some people get a hold of some small nugget of truth that others have not found, he took his truth and began to expound on it and tangentially created many theories about the human race that were not true, did not improve health, would harm people if allowed to happen, and were at best racially flawed, and at worst paternalistically racist. His foundation Racial Betterment Foundation called for racial segregation, anti-racial mixing, anti-immigration of non-whites and more. But to be honest, Kellogg did have foster children who were black who benefited from his parenting and providence. He was wealthy.
Altogether it would be easy to call John Harvey Kellogg a wingnut, but perhaps for all we know being less full of shit, literally, is the key to happiness.