Cause of death: heart failure
Will Keith Kellogg (born William Keith Kellogg; April 7, 1860 – October 6, 1951) was an American industrialist in food manufacturing, who founded the Kellogg Company, which produces a wide variety of popular breakfast cereals. He was a member of the Seventh-day Adventist Church and practiced vegetarianism as a dietary principle taught by his church. He also founded the Kellogg Arabian Ranch, which breeds Arabian horses. Kellogg was a philanthropist and started the Kellogg Foundation in 1934 with a $66-million donation.
Source : Wikipedia