10 Foods That Should Not Be Reheated

Last Updated on Feb 28, 2024 by HappyDieter

Microwaving food is a common practice, but not all foods are safe to reheat in the microwave. It is important to be cautious when reheating bread as it can become dry and tough. Additionally, it is not recommended to store bread in the refrigerator as it can become stale faster. Some foods, like seafood, can lose nutrients or even become toxic when reheated in a microwave due to chemical changes. It is important to be cautious when microwaving leftovers from the refrigerator. It’s crucial to understand which foods, such as bread, should not be reheated in the microwave for a few minutes to preserve their nutritional value and avoid potential health risks. This post will explore 10 specific foods, such as bread and nachos, that should not be reheated in the microwave. We will discuss the reasons behind it and the potential dangers associated with microwaving these foods.

From fried foods like breaded chicken and rice to dishes with peppers and tomato sauce, this article will provide essential insights into why these items, including pizza with melted cheese, pose a risk when subjected to reheating methods such as microwaving or oven heating. Understanding these considerations can help individuals make informed decisions about handling reheated foods, such as bread, and minimizing the risk of food poisoning. Microwaving leftovers and adding garnishes can also be effective methods to ensure the safety of reheated foods.

Key Takeaways

  • Avoid microwaving certain foods like bread, spinach, mushrooms, eggs, and tomatoes to reduce nutrient loss and potential bacterial growth in the microwave.

  • Opt for alternative methods such as stir-frying or consuming these foods at room temperature to retain the nutritional value of heat-sensitive foods like bread and pizza. Avoid microwaving them.

  • Prioritize incorporating fresh fruits, vegetables, lean proteins, bread, fried food, pizza, and reheated foods into your diet to maintain a healthy and balanced meal plan.

  • Be mindful of the potential health risks associated with reheating specific foods, such as bread and pizza, in the microwave, and consider meal planning to minimize the need for reheating.

  • Stay informed about food safety guidelines and best practices to make informed decisions about reheating leftovers, such as bread and pizza, in the microwave, and minimize food waste.

  • Remember that consuming a variety of fresh, whole foods can contribute to overall well-being and nutrition. Additionally, it is important to ensure that these foods are prepared and cooked properly to avoid any issues with heat or microwave.

10 Foods That Should Not Be Reheated

Almost every day we use the microwave to reheat and eat the leftovers from the food we made. We all know what reheating food in the microwave is and many times we hear warnings that it is not safe to reheat certain foods in the microwave. While there is some truth in that, many foods can be reheated in the microwave, as long as it is done properly. But some foods can become even poisonous after reheating. So these are the foods that shouldn’t be reheated:

Rice cakes

1. Rice

Have you ever heard that reheating rice in the microwave can result in food poisoning? It is, in fact, the way fried food is stored before being reheated in the microwave which could mean it carries bacteria.

The problem comes when cooked rice and fried food are kept at an unsafe temperature in the microwave for a longer time, as this environment allows the spores to breed and heat.

No amount of reheating after that can kill them. A bacillus cereus bacterium in rice can cause food poisoning when heated in a microwave. If cooked rice is left at room temperature, bacteria can multiply and may create toxins that cause diarrhea or vomiting. To prevent this, it is recommended to heat the rice in a microwave before consuming. So eating reheated rice in the microwave is not a problem as long as it has been stored in the right way, not standing at room temperature for more than 2 hours, before reheating.


2. Mushrooms

Leftovers, like mushrooms, must be refrigerated no more than two hours after cooking, and eaten the same day without reheating in the microwave.

Of the ten foods on this list, mushrooms present the biggest health risk when heated in a microwave. Mushrooms are often added to many cooked meals and can be easily reheated in the microwave. However, it is important to consume them right after cooking or cold the same evening.

This is true for microwave risottos, as well as microwave soups, which are made with mushrooms. When we microwave reheat the mushrooms, there is a change in the composition of protein that changes the taste of the food. Microwaving mushrooms may cause a variety of digestive problems, and the mushrooms may lose all their valuable nutrients. As a result, all health benefits associated with the mushrooms are gone. Once heated in the microwave, mushrooms change their physical composition, so if the mushrooms are a part of your meal, try removing them before reheating.


3. Celery

Although most people store celery in their fridge and consume it fresh, many times the celery is used in casseroles or soups. Additionally, celery can also be cooked quickly and conveniently using a microwave. So just like spinach, when the celery is heated in the microwave, it releases nitrates when we cool it and then reheat it again.

However, when you are reheating the soup in the microwave, make sure you take out celery since the nitrate contents of celery can cause you big health problems if it goes under reheating for the second time.

Generally speaking, any healthy and good nutritional vegetable that comes around the Celery family or carrot family can turn into toxic food if continuously reheated in the microwave. If you put celery in a soup or casserole dish, microwave your meal instantly and throw the leftovers in the trash can.

Eggs in Basket

4. Eggs

If you cook eggs for breakfast in the microwave, no matter if they are fried or scrambled, and then leave them for later, you should know that you must eat them cold.

Eggs, like chicken, can produce toxic substances when cooked, cooled, and reheated in a microwave at high temperatures.

It is not the rule for foods where the eggs are part of sauces like béchamel, but the rule refers to meals with boiled or fried eggs that are cooked in the microwave. It might sound silly, especially if you have reheated the eggs in the microwave and eaten them before with no consequences. If it was so, you just might have been lucky, but if you don’t want to experience really bad food poisoning, we give you the advice to quit while you are ahead and avoid reheating these dangerous foods in the microwave.

Chicken and Rice Diet

5. Chicken

There is a good reason why most people soon after eating, store their chicken in the refrigerator and then eat it cold the same day.

Once it is cooked and then cooled and reheated, the high level of protein in chicken changes. Like rice and mushrooms, consuming reheated chicken, especially if it is reheated to the highest temperature, can cause food poisoning.

After you reheat it once, you should not reheat it a second time again. Chicken can be safely reheated, just do not use the microwave, but put it in the oven or a toaster oven to heat it slowly but thoroughly. It does take more time than just simply putting it in the microwave for a few minutes, but reheating it slowly will keep you healthy and safe.


6. Spinach

Spinach is a super healthy food that many people enjoy in their salads, but many people eat spinach as a side dish. But did you know that spinach is one of the worst foods that should never be reheated?

Spinach together with other leafy vegetables contains a high amount of nitrate that depends on the variety, season, soil, and water conditions where the spinach has grown.

Nitrate itself is safe and harmless, but as it converts to nitrites, and then again to nitrosamines, we get foods that can be carcinogenic. This mostly occurs after spinach is heated, stored, and then again reheated. It affects the ability of the blood to transport oxygen by transforming hemoglobin, into methemoglobin, a protein that is not able to carry oxygen. So eat it cold or throw out the leftovers.

Rosemary Garlic Sweet Potato Fries

7. Potato

It is not good to leave baked potatoes out at room temperature overnight reheat them and eat them the next day. This is a food safety issue.

Potato, when baked, has a neutral PH factor and can quite easily grow microorganisms. This vegetable is a highly nutritional food that we should not reheat because it loses most of its nutrients, and even becomes toxic.

Consume it tight after preparation or even better cold. Besides the possibility of becoming toxic after reheating, they will lose up to 30 % of their remaining folate and vitamin C. To minimize nutrient loss and prevent possible poisoning, the best way is to consume the potatoes without reheating them. If you are preparing stews for a few days, use the potatoes and add them subsequently.

Beets - Red Ace

8. Beet

Like spinach, beets also contain nitrates, which are very useful for your health, but these nitrates become extremely harmful with reheating.

Because after reheating the chemical composition in beet changes, resulting in foods that are non-edible and dangerous. When the beet is reheated it can become very dangerous for your body, as the whole amount of it can become completely nitrate.

When heating is performed, under the action of microorganisms, it transforms nitrate molecules into nitrosamines. They are carcinogenic to the human body. Beet is among the most harmful vegetables after reheating so it is recommended to be consumed best when fresh. This doesn’t mean that you should not eat this food like other food, but only you should avoid being reheated.

Bar Cento - Roasted Turnips

9. Turnips

The amount of nitrates in turnips can be very harmful to our body if reheated.

Turnip is potentially hazardous food that after we cook shouldn’t be cooled and reheated again the second time, to avoid the food being at temperatures that support the growth of pathogenic bacteria. If pathogens were present in the food, they could multiply to dangerous levels.

You should always be concerned about bacterial growth, however, especially when you put away your cooked turnips a room temperature for two hours or longer before refrigerating it. The two-hour mark is generally considered the point at which bacteria will begin to grow. Because turnips as already said contain a high amount of nitrates, just make sure that it is not left out for a long time and don’t reheat it. The best is to consume this vegetable fresh and well-washed.

New oil and old oil

10. Oils

Although many fast food restaurants freely reheat cooking oil regularly, it is not a healthy habit.

Many studies have shown that reusing cooking oil can expose you to many dangerous toxins, which could lead to serious health issues. In particular, it has been shown that reheating oils like corn, canola, soybean, and sunflower oil release a toxin (4-hydroxy-trans-2-nonenal or HNE).

This toxin has been linked to an increased risk of many health problems, including Alzheimer’s disease, Parkinson’s disease, liver disorders, cardiovascular problems, and cancers. Knowing these risks before and avoiding reheated cooking oil can change your mind about these unhealthy eating habits. Particularly present in restaurants, reheated oil can be harmful if consumed in the long term and should be avoided in most cases.


In conclusion, being mindful of the foods that should not be reheated is essential for maintaining good health and preventing foodborne illnesses. By avoiding reheating certain foods like eggs, spinach, and chicken, individuals can reduce the risk of bacterial contamination and preserve the nutritional value of their meals. It’s crucial to prioritize safe food handling practices to safeguard one’s well-being.

Always remember to refer to credible sources and seek advice from nutrition experts when in doubt about food safety. Sharing this knowledge with friends and family can help create awareness and promote healthier reheating habits among a wider circle. By staying informed and spreading the word, everyone can contribute to a safer and healthier dining experience.


Can reheating certain foods be harmful to health?

Reheating certain foods can lead to the growth of bacteria and cause food poisoning. It’s important to handle and store food properly to avoid any potential health risks associated with reheating.

What are some examples of foods that should not be reheated?

Foods like mushrooms, eggs, spinach, chicken, and rice are best consumed fresh as reheating them can alter their nutritional composition and even lead to bacterial contamination.

How should leftover rice be handled to prevent foodborne illness?

Leftover rice should be refrigerated within two hours of cooking and consumed within 1-2 days. When reheating, make sure it’s steaming hot throughout before serving.

Is it safe to reheat cooked chicken or other poultry products?

Reheating cooked chicken or poultry products increases the risk of bacterial contamination. It’s advisable to consume these items when freshly prepared rather than reheating them later.

Why does the blog recommend avoiding the reheating of specific foods?

The blog aims to raise awareness about potential health risks associated with reheating certain foods. By understanding which foods are best consumed fresh, individuals can take steps towards maintaining good health and well-being.