Conversation so far:
What medical breakthroughs did John Harvey Kellogg make?
Did John Harvey Kellogg invent any new equipment?
John Kellogg invented a hot air bath, vibrating chair, oscillomanipulator, window tent for fresh air, pneumograph to graphically represent respiratory habits, loofah mitt, and apparatus for home sterilization of milk.
How old was John Harvey Kellogg when he started studying medicine?
At age 20, The Kelloggs and the Whites convinced John Kellogg to join a six-month medical course at Russell Trall's Hygieo-Therapeutic College in Florence Township, New Jersey.
What information can you give me about John Harvey Kellogg's inventions?
John Kellogg invented medical equipment, phototherapeutic therapy, electrotherapeutic therapy, mechanical massage devices, and a colon irrigator.
Did John Harvey Kellogg invent any medicines or only equipment?
John Harvey Kellogg developed and marketed a wide variety of vegetarian foods, besides inventing medical equipment, phototherapeutic therapy, electrotherapeutic therapy, mechanical massage devices, and a colon irrigator.

Question: What foods did he invent?
Self-contained rewrite: What foods did John Harvey Kellogg invent?