You Should Never Reheat These Foods

Although reheating dinner is a modern way of life, some foods are not “meant” to be consumed reheated.

Whether it’s Friday night and you need to clean out your fridge, or you want to turn your leftovers from last night into a whole new meal, our microwaves are our handy kitchen companions. But research shows that reheating some of your favorite foods can be dangerous to your health, especially if they were stored wrongly beforehand.

Here are some of those foods and why you should refrain from giving them a second go in the oven, on the stove or the worst – in your microwave.

1. Celery

Celery with its high nitrate content can become toxic if you heat it the second time and eat it. People usually use celery to prepare soups. Just like spinach, celery also contains nitrates that transform into nitrites after being reheated. If you have made a soup with some celery in it, you should either eat the whole soup immediately, or remove the celery before you warm the soup. The same thing goes for carrots.

2. Mushrooms

Ideally, this food should be eaten the same day of their preparation owing to their complex protein content. Proteins can deteriorate as soon as you cut them up, and that’s bad news for your belly. For this reason, before you cook them, take the exact amount you think is enough to “tame” your hunger.

Remember: Reheated mushrooms present the highest health risk. They should be eaten immediately after being prepared, or eaten cold the following day. When you eat reheated mushrooms, you put yourself at risk of having digestive and even serous heart problems!

You must be careful of the types of leftovers you put in the oven or in the microwave.

3. Chicken meat

Chicken meat, just like mushrooms, contains proteins which are negatively affected when reheated. The protein composition in this common dinner staple actually changes when cold, refrigerated chicken is heated for the second time. This is a reason for worry since chicken contains much more protein compared with red meat. This can actually cause digestive troubles, so if you prefer to reheat your meat, make sure that it is thoroughly cooked: the inside of the reheated meat should be piping hot!

Remember: Chicken meat should be eaten cold. If you absolutely need to reheat the chicken, be sure to do it on a low temperature for a long period. Chicken meat can cause severe digestive problems when reheated after a day or two of its first cooking. The best way to consume stored chicken is to put it in a cold salad or a cold sandwich.

4. Spinach

Like a number of other leafy greens, spinach is rich in iron and nitrates. In the case of reheating, these nitrates can transform into nitrites and other known carcinogens.

5. Eggs

They may be a morning staple and protein powerhouse, but eggs should not be exposed to heat time and again. Reheating eggs at high temperatures (after they have been boiled or fried) can make them especially toxic and wreak havoc in your digestive tract.

6. Rice (whatever its color is!)

Again, how you store it before heating can lead to problems. The Food Standards Agency stated that “Uncooked rice can contain spores of bacteria that can cause food poisoning. When the rice is cooked, the spores can survive, however, if the rice is left standing at room temperature, the spores will multiply and may produce poisons that cause vomiting or diarrhea. Reheating the rice won’t get rid of these poisons.”

7. Turnips

We all put turnips as a common ingredient in our soups and stews. Due to their high amount of nitrates, reheating of this vegetable is not advisable at all, since it can become toxic!

8. Oils

Grape seed oil, walnut oil, avocado oil, hazelnut oil, and flaxen seed oil all have very low smoke points. That is why, when you reheat them, they become rancid. So, do avoid using them as cooking, baking or frying oils!

Rather, sprinkle or drizzle them over your meals at the end of cooking to enhance the taste of the food.

9. Beets

Just like spinach, this vegetable is very rich in nitrates. Because reheating beets can cause a lot of discomfort, you should eat your leftovers cold NOT reheated.

10. Butter Lettuce

You can reap the benefits of this green leafy vegie if you eat it raw. Cook it if really must, but never ever reheat butter lettuce, as the high amount of nitrates can easily cause food poisoning!

11. Potatoes

Potatoes are a nutritious and yummy bite, but, unfortunately, they lose their nutritious value if you let them rest at room temperature for a long time. In such case they can actually become toxic and cause nausea or illness, most often food poisoning.

And potatoes are very tricky—if they’re left to cool down at room temperature (after cooking them) instead of immediately refrigerating, the warm temperatures can promote the growth of botulism, a rare bacterium. Botulism can’t be killed with a quick zap in the microwave, so it’s best to refrigerate them immediately to avoid any problems with reheating. On the other hand, if you intend to eat your potato stew for a couple of days, take the potatoes out and just add them subsequently.


Recapping: When we have leftovers, we like to reheat and consume them for the second and third time, especially if it is our favorite food. However, some foods are safe to consume after reheating, and others are not and can cause damage to our organism. It may be hard to believe that some healthy foods, when reheated, can be a possible danger to us, but these healthy foods lose their nutrients after we warm them up.

Anyway, continuous reheating of your daily meals is toxic and causes bloating when it comes to foods listed above. To be on the safe side, avoid reheating them!