Celery
Celery contains nitrates that turn into toxic nitrites and carcinogenic nitrosamines after reheating. And why are you warming up your celery anyway?
Eggs
Eggs can become toxic after reheating and the are, to use a technical term, grody.
Potatoes
I know, I am just as shocked as you are. We’re talking potatoes here. Po-tay-toes. Boil ‘em, mash ‘em, stick ‘em in a stew…just DON’T microwave ‘em because reheated potatoes lose their taste and health benefits and can even become a cause of botulism if they’re stored in foil at room temperature.
Mushrooms
After reheating the protein composition of mushrooms changes, and this causes stomachache and stomach bloating. The best use for leftover shrooms is a pasta sauce or in a salad.
Beets
It was nitrites before but now we’ve got nitrates. Different spelling, same problems.
Chicken
When you reheat chicken the protein composition changes, leading to digestive issues. You’re better off to make a chicken salad sandwich instead.
Spinach
Just like celery, spinach is full of nitrates that become nitrites and nitrosamines after reheating.
Rice
Rice has a high chance for contamination when left at room temperature so make sure you don’t leave it sitting for long, and if you do, don’t even THINK about putting it in the microwave…I heard that! NO THINKING.