food vs mental object

food and mental object both are nouns.

Word	Noun	Adjective	Verb	Adverb
food	Yes	No	No	No
mental object	Yes	No	No	No

As nouns, mental object is a hypernym of food; that is, mental object is a word with a broader meaning than food:

food: anything that provides mental stimulus for thinking
mental object: the sum or range of what has been perceived, discovered, or learned

Other hypernyms of food include cognitive content, content.

food (noun)	mental object (noun)
any substance that can be metabolized by an animal to give energy and build tissue	the sum or range of what has been perceived, discovered, or learned
anything that provides mental stimulus for thinking
any solid substance (as opposed to liquid) that is used as a source of nourishment