Yes that would be part of the whole thing, Liquids would have Stats for what happens when they are consumed. Milk wouldn’t be nothing it would provide sustenance, Water would provide Hydration, etc.
And if we go with Acid it would not always be instant death. You could for example drink something similar to Stomach Acid and still be mostly fine apart from a little bit of damage in your mouth and throat, as anyone who ever vomited in their Life can attest you.
This way being immune to certain types of Food Poisoning is easier to handle. Each Poison, Venom, Bacterium, Virus and Parasite will have a sort of ID in order to categorize them, with 26 Categories for each of them, so you can be immune to Poison A, but the Poisons B to Z are all effective on you, and there is a few random Plants somewhere containing an Antidote for the Poisons W, T and F that happen to grow on your Island, even though nothing on it deals Poison W or F Damage, though that random Lizard in the Mountains does deal Poison T Damage when eaten.
Ingame you usually don’t exactly know the Category ID of a Poison or so, you typically only know “This thing happens to have a poison that this bottle of cure happens to be effective against”, so you need to find at least 2 Poisonous things that happen to have the same Category before you know which Letter they are, but you only find out the Letter of other 3rd or 4th Poisons/Cures by actually experimenting, and even then it can happen that you have an Animal that is not only Poison A but L, S and O too, in which case good luck not only finding a mixture that can cure that bullshit, but also separating the category Letters for scientific purposes to find out how it all works in the backend of the Game.
Edit: Some NPCs will often know some of the Poisons and their Cures in advance, so you might be able to find out by asking them, or buying Recipes from them.