Be Careful: 6 Common Foods Become To.xic When Reheated — It's Best to Throw Them Away
Below are 6 types of food you should discard instead of reheating!

In daily life, storing leftovers in the fridge and reheating them later is a common habit. However, not all foods are safe to reuse. Some familiar dishes can become toxic or harbor harmful bacteria when reheated. Here are 6 types of food that should be thrown away instead of being reheated:

1. Mushrooms

Mushrooms contain a lot of protein and enzymes that break down when reheated, producing harmful compounds that can cause digestive disorders. According to Dr. Trinh Thi Hai Yen (nutritionist at Bach Mai Hospital), reheated mushrooms may lead to bloating, diarrhea, or mild food poisoning due to degraded proteins that are no longer safe for consumption.

2. Seafood (fish, shrimp, squid...)

Seafood spoils easily after storage. When reheated, toxins from bacteria may cause digestive issues or even liver infections. If stored too long or reheated improperly, seafood can contain toxins that cannot be destroyed even at high temperatures, increasing the risk of food poisoning.

3. Spinach and Leafy Greens

Spinach contains high levels of nitrates. When reheated, nitrates can convert into nitrites and nitrosamines — compounds known to be carcinogenic. Dr. Hoang Thi Lan Anh (Hanoi Center for Disease Control) advises: “Do not reheat spinach, especially not in a microwave or multiple times. It's best to eat it immediately after cooking.”

4. Soft-Boiled Eggs

Soft-boiled eggs may contain Salmonella, a bacterium that can cause diarrhea and food poisoning. Reheating often fails to kill these bacteria completely. Therefore, soft-boiled eggs should be consumed immediately after boiling and not stored in the fridge or reheated.

5. Tremella Soup

Tremella (snow fungus) is praised as a “beauty elixir” and widely used in soups for skin and health benefits.

However, this mushroom contains relatively high nitrate levels. Once cooked, nitrates may degrade into nitrites — compounds that are harmful to health.

Nitrites can disrupt digestion and, when accumulated over time, may impair the body's ability to produce blood normally. Thus, it's best to consume Tremella immediately after cooking and avoid reheating.

6. Milk

Milk is often warmed before drinking to enhance flavor and digestion. However, once heated, it should not be reheated again after cooling. Repeated reheating breaks down milk proteins and causes a significant loss of nutrients.

Drinking milk that has been reheated multiple times not only reduces nutritional value but may also cause digestive disorders or diarrhea. To ensure your health, heat milk only once and consume it right away. Avoid reheating it multiple times.

In Summary:

While reheating food is convenient, it's not always safe. The six types of food above can become harmful when reheated, posing risks from mild food poisoning to more serious health issues.

Tips:

• Eat food immediately after cooking.

• If storage is necessary:

  • Cool within 2 hours and consume within 24 hours.

  • Reheat only once, ensuring internal temperature reaches ≥ 74 °C (165 °F).

Following proper food storage and reheating practices will help protect your family's health effectively.