Food can be poison or medicine. And the same food can be one or the other, depending on time, amount, and combination. I have known this – from personal experience – since my teens, and am reminded of it daily.
Sometimes, even the food that normally makes me sick, is exactly what I need to feel better. After several months in Nepal and India, I spent a few days near the beach by Los Angeles, and ate 5-7 milkshakes daily. It was just what my organism needed at that time, although I rarely if ever eat milkshakes otherwise.