Nitrite belongs to inorganic compounds, similar to the appearance of salt, taste bitter or slightly salty astringent, commonly found in cured meat products, pickles and spoiled vegetables. Nitrite, mainly in the form of sodium nitrite or potassium nitrite, daily life of vegetables if stored for too long, will also produce nitrite, such as cabbage, spinach, leeks, radishes, etc., these vegetables rot and spoilage or pickling impermeable, placed for too long after the nitrite will be produced. Nitrite is more common in daily life, such as long-term intake or excessive one-time intake, can cause damage to the nervous system, gastrointestinal tract, and can even lead to a drop in blood pressure and cardiac arrhythmia and other serious hazards, so we should try to avoid eating decayed or pickled impermeable vegetables.