Hear me out. There’s nothing innate to an object that makes it “food”. It’s an attribute we give to certain things that meet certain qualities, i.e. being digestible, nutritious, perhaps tasty or satisfying in some way, etc. We could really ingest just about anything, but we call the stuff that’s edible “food”. Does that make it a social construct?
“digestible” and “nutritious” aren’t social constructs, so no. If your body can transform it chemically in a way that produces energy, it’s food. Otherwise it’s not. The same things are food regardless of your culture.