The whole plot of The Secret Life of Walter Mitty is that the main character has weird flashbacks to past events or dreams. The reader or viewer is never sure whether the scene is real or imagined due to the spontaneity of these reflections/flashbacks. It makes for an interesting movie and an interesting story when these responses are elaborately fantasized, as Thurber did.
Answer: According to the speaker, headlines about the benefits of chocolate and cheese came about when the scientist was doing studies with a drink that made people have less tryptophan in the brain.
