Breakfast cereal he launched the Cornflakes brand, which overnight captured a national market. Soon there were forty rival manufacturers in the Battle Creek area. His brother William K. Kellogg (1860–1951) worked for him for many years until, in 1906, he broke away, bought the rights to Cornflakes, and set up the Kellogg Toasted Corn Flake Company. William Kellogg discarded the health food concept, opting for heavy advertising and commercial taste appeal. Later, his signature on every package became the company trademark. The second major innovator in the cereal industry was Charles W. Post, a salesman who was admitted to Kellogg's sanitarium as
Merritt Kellogg 180° meridien. The Kelloggs transferred to Australia in May 1900. They settled in Sydney, where Kellogg drew up the plans for the Wahroonga Sanitarium, and in 1901 supervised its construction. This is now the Sydney Adventist Hospital. Kellogg returned to California in 1903 and due to poor health lived in retirement. He was suffering from hearing and vision problems. He lived the last nineteen years of his life in Healdsburg, California. Kellogg was the older brother, or half-brother, of Dr. John Harvey Kellogg, who was expelled from the Battle Creek church on suspicion of unorthodox views and suspect practices at