Mr. Li’s daily eating habits play a crucial role in his health. As the primary provider for his family, he often works long hours and frequently returns home late at night, exhausted and hungry. To save time, he purchases a large quantity of food on weekends, storing everything in the refrigerator and relying on these supplies for the following days.

Inside Mr. Li’s fridge, one can find vegetables, fruits, meat, and even leftovers. However, few realize that this seemingly convenient approach to meal planning can pose serious health risks.

Doctors warn that while refrigerators help extend the shelf life of food, they do not guarantee safety in all cases.

Here are five types of food that should not be stored in the refrigerator for extended periods, as they can become breeding grounds for harmful toxins and even contribute to cancer risk.

1. Green leafy vegetables

Leafy greens like spinach, cabbage, and lettuce naturally contain nitrates. When stored in the refrigerator for too long, these nitrates can transform into nitrites, which are associated with an increased cancer risk.

This is especially concerning for sautéed or fried green leafy vegetables that contain high amounts of oil. Studies show that their nitrite levels can rise significantly after being kept in the fridge for just 16 hours.

2. Repeatedly thawed meat

Repeatedly freezing and thawing meat leads to bacterial growth and the accumulation of harmful substances, including carcinogens like P-ammonium dinitrate. Each freeze-thaw cycle increases the concentration of these compounds, raising potential health risks.

To minimize this danger, it is advisable to divide meat into small portions before freezing, ensuring that only the necessary amount is thawed at a time.

3. Leftovers

Leftover food, if kept too long, can develop bacteria, mold, and harmful toxins. Protein-rich foods such as meat and soy-based dishes are especially prone to spoilage.

Once consumed, these toxins can pose severe health risks, including an increased likelihood of cancer. To stay safe, leftovers should be eaten as soon as possible rather than stored for extended periods.

4. Opened milk

Milk and dairy products like yogurt and cheese contain high amounts of protein and fat. Once opened, these products are susceptible to spoilage, even in the refrigerator, as bacteria and microorganisms quickly multiply.

Spoiled dairy not only loses its nutritional value but can also cause liver damage. To avoid this, dairy products should be consumed as soon as possible after opening.

5. Pickled foods

Pickled items such as salted fish, bacon, and kimchi contain high levels of salt and preservatives. When stored in the refrigerator for too long, they can foster bacterial and fungal growth, leading to the production of harmful compounds like nitrite.

Once inside the body, nitrites can convert into nitrosamines, which are known carcinogens. Prolonged consumption of these substances may increase the risk of digestive cancers, such as stomach cancer.

While refrigeration helps preserve food, it is essential to understand its limitations. Paying attention to proper storage methods and consumption timelines can help reduce health risks and ensure food safety.