Dr. John Harvey Kellogg opened a sanitarium in Battle Creek, Michigan, where he practiced his unusual methods for maintaining health, including colonic irrigation, electrical stimulus and sexual abstinence, vegetarianism and physical exercise. The sanitarium attracts well-to-do patients including William and Eleanor Lightbody, who are suffering from poor health following the death of their child. On their way to Battle Creek they meet Charles Ossining, hoping to make a fortune by exploiting the fad for health food cereals. Ossining finds a partner in Goodloe Bender. Having enlisted the services of George Kellogg, the doctor's estranged adopted son, they attempt to produce "Kellogg's Perfo Flakes." In the sanitarium, Will Lightbody is separated from his wife, and is soon harboring lustful thoughts toward Nurse Graves and patient Ida Muntz. His wife Eleanor, meanwhile, befriends Virginia Cranehill, who has a modern attitude toward sexual pleasure, influenced by the works of Dr. Lionel Badger. Will eventually succumbs to Ida Muntz's charms. Later he learns that Ida has died during treatment. Following the death of a patient in the sinusoidal bath, and the discovery of yet another death, Will suffers a breakdown, flees the sanitarium, gets drunk and eats meat. At a restaurant, he meets Ossining, and agrees to invest $1,000 in his health food business. Will returns drunk to the sanitarium, where he is reprimanded by Dr. Kellogg and is abandoned by a distraught Eleanor. Ossining's business is a disaster, with no edible product. He and the partners resort to stealing Kellogg's cornflakes and repackaging them in their own boxes. Ossining meets his aunt, his sole investor, on visiting day at Kellogg's sanitarium, and is there exposed as a fraud and arrested. Nurse Graves attempts to seduce Will, who is guilt-stricken and spurns her advances. He searches for Eleanor, only to find her and Virginia Cranehill receiving clitoral massages from Dr. Spitzvogel while Dr. Badger masturbates. Will is incensed, thrashes Dr. Spitzvogel with a branch and takes Eleanor away. George Kellogg visits his father, but things go badly. George burns down the sanitarium. In the ensuing chaos, Ossining escapes. Kellogg seems to reconcile with George in the mud bath in the aftermath of the fire. In a final coda, the Lightbodys have reconciled and are happily married, with four daughters. Will receives a check for $1,000 from Ossining, who has become a cola beverage tycoon. Dr. Kellogg dies of a heart attack while diving from a high board.
The film received mixed to negative reactions upon its release, with much criticism towards the scatological nature of the film. Hopkins' portrayal of Kellogg was singled out for criticism. The film has a 41% rating on Rotten Tomatoes based on 17 reviews. Despite this, not all reviews were negative. Writing in Bright Lights Film Journal, Tanfer Emin-Tunc commented: "It is a sophisticated blend of humor and documented historical material that seeks to question the various forms that race and class have assumed in twentieth-century American society." The film flopped at the box office, opening at #5 with $2,580,108 in its opening weekend and grossing $6,562,513 domestically in its entire run.
