Potatoes are loaded with nutritional elements but if you cool them at room temperature, reheating potatoes would facilitate the growth of botulism bacteria. So there are two things: i) either keep them in refrigerator or ii) do not reheat them.
Eating chicken cooked earlier some days is not suitable for stomach. When chicken turns cold, its protein composition is changed. Reheating cold chicken causes digestion problem. Chicken once cooled should be eaten cooled however it you prefer re-heating it, heat it for longer on low temperature.
Ass eggs are fully loaded with proteins, reheating cooked eggs is very dangerous for health. It can cause trouble in your stomach.
Spinach and similar leafy vegetables contain high amount of nitrates which make no harm to humans but when reheated, nitrates are transformed into nitrites and nitrosamines which are very harmful to our health. Therefore, always avoid reheating spinach in any form.
Beets also contain nitrates. When heated another time, they release carcinogenic properties which cause harm to humans. Beet should not be reheated and can be used cooled.
You would do something with leftover of your lunch, dinner and other meals. Yes. In every home, foods are left and then reused at the next meal time but there is no cognition about the health hazards attached to it. In general, it is always recommended to not to use stale food but even then people try to manage the leftover for at least next couple of meals.
Here KFoods.com is presenting a list of top 5 very common foods which you should not reheat and reuse. These are vegetables and meat foods; heating them more than once (second time after cooking) jumbles up their nutritional values making them hazardous for the health.
Here are the 5 foods to never reheat and eat.