While heating food is a common practice, some foods can become harmful when overheated. This is because high temperatures can alter their composition, leading to the formation of potentially toxic compounds or the loss of essential nutrients. Here are six foods you should avoid overheating:

• Spinach and Leafy Greens: Vegetables like spinach, broccoli, carrots, celery and other green leafy vegetables are rich in nitrates. When these vegetables are reheated, the nitrates can be converted into nitrites and nitrosamines, some of which are carcinogenic. These compounds may have negative health effects.

• Eggs: Reheating boiled or scrambled eggs can cause the proteins to denature and potentially become toxic. Additionally, reheating eggs may release sulfur compounds, which can negatively impact digestion.

• Chicken: Chicken has a different protein composition, and reheating it can cause changes that may lead to digestive problems. It's best to consume chicken immediately after cooking or eat it cold if stored. Repeatedly reheating chicken, particularly at high temperatures, should be avoided.

• Mushrooms: Mushrooms are best consumed immediately after cooking. They contain proteins and minerals that can be broken down and generate toxins when reheated. If you must store mushrooms, it's recommended to eat them cold the next day.

• Potatoes: Cooked potatoes left at room temperature can foster the growth of Clostridium botulinum, a bacterium that produces a dangerous toxin. Reheating might not eliminate this toxin, so it's crucial to refrigerate potatoes promptly after cooking and ensure they are thoroughly heated if you choose to reheat them.

• Oils: Certain oils, like sunflower, avocado, flaxseed and grapeseed oil, have low smoke points. Overheating these oils can cause them to degrade and release harmful compounds and free radicals. It is best to use oils with high smoke points like peanut or canola oil for high-heat cooking.

Beyond these specific foods, it's important to be mindful of cooking methods. High-temperature cooking methods like grilling, frying, and searing can lead to the formation of harmful compounds such as heterocyclic amines (HCAs), polycyclic aromatic hydrocarbons (PAHs), and advanced glycation end products (AGEs). These compounds have been linked to an increased risk of cancer and other health issues.

To minimize the risk of forming these harmful compounds, consider using lower-temperature cooking methods like steaming, poaching, or stewing. When grilling or frying, avoid charring food and ensure cooking utensils are clean to prevent residue from undergoing chemical transformations.

Additionally, consider the storage of leftovers. Cooling food rapidly and storing it at appropriate temperatures can help prevent bacterial growth. It's generally recommended to reheat food only once and to ensure it's heated thoroughly to a safe internal temperature.

Being aware of which foods are best not reheated and adopting safer cooking practices can significantly contribute to a healthier diet and reduce the risk of exposure to harmful compounds.