Food Safety | Should we not eat overnight food as it causes cancer? Here comes the authoritative answer

In our daily lives, we often hear that eating leftover food can cause "poisoning," "cancer," and "excessive nitrite." However, when faced with leftovers, many people feel troubled. It's a pity to throw them away, but keeping them for the next day raises concerns about safety. Can we eat leftover food?

Many people worry that eating overnight food is unhealthy because they have heard that "excessive nitrite in overnight food can cause cancer." In fact, nitrite itself is not carcinogenic. It is contained in vegetables and meat to a certain extent, but the nitrosamines produced after the digestion reaction in the stomach can cause cancer. If we put overnight food in the refrigerator, take it out and heat it up the next day before eating it, its nitrite content is generally within the normal range. If it is not put in the refrigerator and combines with bacteria in the air to produce a certain reaction, nitrosamines may exceed the standard. Eating such overnight food for a long time will lead to an increase in the incidence of digestive system tumors. Digestive tumors such as intestinal cancer, liver cancer, and gastric cancer have a clear relationship with nitrosamines.

In life, if people's body resistance is not strong and they eat overnight food, it is easy to cause acute gastroenteritis, nausea, vomiting, abdominal pain, food poisoning and other diseases; followed by dehydration and loss of electrolytes, which may cause a drop in blood pressure, dizziness, arrhythmia or hypotension. So try to eat less overnight food, cook as much as you want to eat, even if you can't finish it and don't want to throw it away, put it in the refrigerator in time and heat it up fully next time before eating.

What foods are not suitable to be eaten overnight?

1. Overnight seafood

Aquatic products such as shrimp, crab, and shellfish are often contaminated by low-temperature-resistant microorganisms. When cooking these seafood, in order to make them fresh and delicious, they are usually heated for a short time, which poses a risk of the reproduction of pathogenic microorganisms. Eating overnight seafood can also cause damage to the liver and kidneys.

2. Overnight salad

Leftover salads have a shorter shelf life after being stirred with chopsticks, and bacteria have more opportunities to multiply. Therefore, salads should be cooked as much as you eat.

3. Overnight soft-boiled eggs

Uncooked eggs may contain a variety of pathogenic bacteria such as Salmonella. If they are left for a long time, they are more likely to breed bacteria and harm the intestines after consumption.

4. Overnight vegetables

The food that is most likely to produce nitrite is vegetables, because vegetables contain a substance called nitrate, which is harmless. However, under the action of bacteria, the nitrate in vegetables will turn into nitrite, which is the carcinogen we are worried about.

Expert interviewed: Xu Hao, attending physician of neurosurgery at the First Affiliated Hospital of University of Science and Technology of China