spoilt food

food that was off / that had gone off

auch: stale food

https://www.collinsdictionary.com/dictionary/...

'stale bread' ist einfach altes, hartes Brot, das ist nicht per se verdorben

@AnnaUK, auch diese eindeutige Übersetzungsanfrage D --> E darf in der Rubrik "Englisch gesucht" gestellt werden.

ate bad food (ambiguous) / food that had gone bad (not ambiguous); got food poisoning

Re #2: In AE, that would typically be "spoiled."

Re #3: "off" is typically marked as BE. If the translation is meant for a more international crowd instead of only BE, one of the other choices might be preferable. (That said, I'd say that many AE speakers would understand "off" in this context, even if they wouldn't use it themselves.)

Looking at the Collins definition in #4, I don't think that even that definition would indicate that you could get food poisoning from "stale food." It's more likely to be unpleasant, but not something that would make you sick.