Leftover food stored in the fridge and eaten the next day is a common habit in many Vietnamese households. However, this habit carries many hidden risks.

Vietnamese people often try to save money by storing leftovers in the refrigerator to eat the next day, sometimes even keeping dishes like braised meat or fish for 3 to 4 days. This is an extremely dangerous habit that can harm the body.

According to Straits Metropolis Daily, a 2-year-old boy named Xiao Lang from Fuzhou, China, was healthy but suddenly vomited blood. Within 5 hours, he vomited 7 times. When admitted to the hospital, Xiao Lang fell into a coma.

Doctors said the boy’s internal organs might be failing, threatening his life. Fortunately, after 8 days of fighting for his life, Xiao Lang recovered.

When asked what he ate before hospitalization, his family said he had eaten salted duck eggs that had been left overnight. After investigation, doctors confirmed this was the cause of his poisoning.

Besides Xiao Lang, another case involved a 28-year-old man who developed acute kidney failure, life-threatening, after eating vegetables and steamed buns left overnight in the refrigerator, Business Daily reported.

These two cases show a reality: some foods left overnight are very dangerous. Not only young children with weaker immune systems, but even healthy young adults can be severely affected.

Not long ago, Dr. Tran Quoc Cuong, a lecturer in nutrition and food safety at Pham Ngoc Thach University of Medicine, shared in a newspaper that if food is not stored properly, harmful bacteria can invade, causing chemical changes that lead to poisoning.

---

Below are some of the worst foods that should never be left overnight:

Leafy Green Vegetables
Usually, nitrate content is highest in mustard greens, followed by cucumbers, and then cauliflower. So if you buy too many vegetables at once, it’s best to eat leafy greens like spinach and cabbage first.

Experts also warn that in summer, if leafy greens are not completely eaten after cooking, it’s best to discard the leftovers and absolutely not leave them overnight, especially spinach and celery.

The reason is that the nitrate in these vegetables is relatively high. After cooking and storing for a long time, it can easily convert into nitrite — a very dangerous carcinogen.

Seafood
Seafood such as shrimp, crab, and cooked fish left overnight undergo protein degradation, which can damage the liver and kidneys. If you buy a lot of seafood but can’t finish it, you can store it in a bag or container and freeze it, then gradually cook it later.

Eggs
All types of boiled eggs, especially soft-boiled eggs, should not be stored for long. The fats and proteins in eggs can easily degrade.

Moreover, harmful bacteria in eggs might not be fully eliminated, and since eggs are rich in nutrients, they easily encourage bacterial growth.

Mushrooms and Wood Ear Fungus
The ideal consumption time for mushrooms is the same day, because if left overnight, the complex proteins in these foods can harm the digestive system if reheated. Additionally, mushrooms and wood ear fungus, whether cultivated or wild, contain high levels of nitrates.

If mushrooms are stored for too long, their nutritional value declines, nitrates become toxic, and can cause stomach discomfort.

Soup Left Overnight in Metal Containers
Leftover soup stored overnight in metal containers such as aluminum or stainless steel can easily produce toxic substances harmful to health.

If you want to save soup for the next meal, it’s best not to add any extra seasoning and store the soup in ceramic or glass bowls in the fridge.

Braised Dishes
Even if stored in the refrigerator, braised dishes left overnight can still cause poisoning. Refrigerators contain many hidden “killers” ready to cause illness.

Soy Milk
Freshly made soy milk has a very short shelf life, and should be consumed within 2-4 hours at room temperature. Beyond this time, bacterial growth increases significantly.

Therefore, after cooking, soy milk should be consumed immediately or cooled and stored in the fridge to prevent spoilage. However, soy milk should not be kept in the fridge for more than 12 hours.

Green Tea
Green tea left for a long time usually turns dull in color. The vitamin C and antioxidants in the tea will also be destroyed. If consumed after long storage, green tea can be contaminated with harmful bacteria and fungi.