Please stop adding mis-information about how "multiple instances" of food poisoning work. You know who you are.
I don't know where you have your information from. I have mine from the game files, plus testing in-game.
I'm absolutely certain that there is no way that someone could have 2 concurrent instances of food poisoning. Moreover, the game really only applies the 10% per hour damage when the player has more than 15% health. If you don't believe me, go install a decompiler like ILSpy or dnSpy and check for yourself.