Sometimes, last night’s dinner is a real-life saver when you need a hot and ready lunch. Even so, there are some foods that you should think twice about reheating.

While it’s a great way to save more money (actually, it is highly advised in any conversation related to budgeting your household), some leftovers might actually pose a hazard to your health.

So, truth to be told, you need to know which foods can be saved and which can’t. How long foods are safe in your fridge depends on many factors, such as safe preparation, proper storage, and what type of food it is. Let’s see which foods you should never keep as leftovers.

…Click “Next” to see which leftovers we’re talking about!

10 Leftovers That Aren’t Good for You:

Eggs

According to Kantha Shelke, Ph.D., and a food scientist and principal of Corvus Blue LLC, eggs most of the time contain salmonella. Plus, some methods to cook eggs require gentle heating for a SHORT duration of time (especially those recipes that require a runny yolk), so it’s possible that the bacteria aren’t even killed after cooking.

If you leave them at room temperature, that bacteria might multiply to harmful levels. Even more, eggs are always better tasting when they are fresh, and they don’t require such a long amount of time to be scrambled, so they’re not the kind of food that you should be keeping as leftovers.

Beets

There’s a study published in 2012 in “Sports Magazine” that shows how the nitric oxide in beets is great in helping your blood pressure and can give your workout the needed boost. At the same time, those compounds react badly in contact with heat.

When foods that are rich in nitrates are cooked, and then not cooled properly, they might be carcinogenic, because they transform into nitrosamines. So, if you regularly eat reheated beets or beet products, you might want to reconsider these leftovers a little bit. It’s best to look out for all the root veggies that are high in nitrate, like turnips, for example.

Potatoes

While spuds are cooked longer and at bigger temperatures than eggs, they can still represent a risk when they’re left to be stored at room temperature for too long. You can foster the growth of a bacteria called “Clostridium botulinum”, which causes botulism.

Even more, large foil-wrapped baked potatoes are even more at risk, because they are wrapped in the perfect environment for bacteria: with low oxygen. And there’s more: potatoes are one of the foods you should never reheat in a microwave. Weird, right? Apparently, zapping them for 60 seconds won’t kill the stuff that has a bad effect on your GI system. The bottom line is: Potatoes shouldn’t be eaten as leftovers.

Spinach

Just like beets, spinach is another type of food that’s rich in nitrate. So, as you might expect, we say that it’s best for you to serve your spinach raw, or lightly sautéed, which will not only save you a lot of time, but it will also be healthier and safer.

Also, it’s worth mentioning that nitrates, which are another byproduct of heating foods rich in nitrate, aren’t safe for infants that are less than 6 months old. In baby purees, spinach is oftentimes mixed with other foods, so it’s advised not to reheat them as leftovers. Even though it has a couple of usage rules, spinach is overall one of the healthiest vegetables.

Rice

There was a number of food poisoning outbreaks that have been associated with rice as leftovers in the 1970s. Ever since then, there has been an increased awareness for a microorganism in rice called “Bacillus cereus”, which apparently multiplies at room temperature.

Don’t rush into throwing out all your uneaten rice, just don’t forget to store it in the fridge rapidly. Food safety guidelines mention that it’s important to keep your foods hot or cold if you’re not going to eat them within two hours. And make sure that when you reheat rice, it’s steaming hot in all the places! Plus, make sure you don’t reheat it more than once!

Chicken

Just like eggs, raw chicken often contains salmonella, therefore you should avoid them as leftovers. So, time in combination with low temperatures is the perfect recipe for disaster. If you want to avoid it, make sure that the internal temperature of the chicken reaches 165 degrees.

And remember that microwaves don’t always heat evenly or as well as other ways of cooking. Also, according to the CDC, it’s advisable not to wash raw chicken, because chicken juices can spread in the kitchen and contaminate other foods or countertops. Using a separate cutting board for raw chicken is also highly recommended, as the meat juices can contaminate the side dish you might prepare.

Cold-pressed oils

Cold-pressed oils, also known as the healthiest oils we could possibly ask for – flaxseed oil, olive oil, canola oil, and other seed oils. They’re all rich in omega-3 fats, and numerous unsaturated fats that are a real marvel to our health. Also, they’re extremely sensitive to temperature.

So if you cook something with one of these oils, just remember that reheating them can make them unstable, rancid, and…unsafe. When you re-use the oil, it can create free radicals that are a danger to your body in the long run. These free radicals are carcinogenic, and they can have a great impact on your overall health.

Oily foods

While we understand you don’t want to throw out your delicious recipe of french fries, saving them as leftovers and reheating them in the microwave might make the oil smoke past its safe level. There’s even a study published in “Food Chemistry” that shows how reheating already cooked oil produces hazardous fumes that might damage your health.

Even so, there are other ways to reheat fried foods. They have the best chance of getting that crispiness you’re looking for again if you heat them in dry heat. You can place it in an oven or a toaster oven that’s preheated to 400 degrees. Plus, make sure the food doesn’t simmer in any excess grease.

Buffet food

Have you ever wondered why buffets don’t let you take food for leftovers? Or better yet, have you ever noticed? Buffet trays aren’t hot enough to kill all bacteria, which can become dangerous if they sit out unrefrigerated.

Most professional catering restaurants follow strict food safety guidelines in order to prevent any possible food-provoked illness, but buffets aren’t so strictly controlled. If you’re hosting a buffet-style party, make sure you never add fresh food to an already-filled serving dish and don’t forget to discard perishables left out at room temperature for more than two hours. It’s best for you and your guests.

Seafood

Fresh fish is extremely healthy, but you have probably heard that bad seafood is one of the top 3 foods that could poison you. In this case, even ambient temperature in the room can be dangerous, so make sure you never leave seafood out of the fridge for too long, nor keep it as tasty leftovers.

According to the Food and Drug Administration, bacteria that is responsible for causing illness is flourishing quickly at warm temperatures that are between 40°F and 140°F. When it comes to shellfish, they should be immediately consumed after being cooked. But you should know that, just like fresh mussels, clams are completely inedible after being thrown into the microwave.

What did you think about all these leftovers we’ve listed? Were you surprised? Also, let us know if we missed any by leaving us a comment in the section below!

If you enjoyed reading this article, we also recommend reading: 12 Beloved Foods you didn’t know are this salty