No it is a food. But it's like a pablum that babies eat. That's not what I mean, though. It's used as a noun also is what I mean.

milquetoast mĭlk′tōst″ noun

One who has a meek, timid, unassertive nature.a timid, unassertive man or boy fearful of confrontation and easily manipulated and dominated.A person of meek or timid disposition.

I guess back a long time ago there was a comic strip called Mr. Milquetoast, with situations where the character in the comic was too weak or servile to stand up for himself or be assertive.