Sodium is a metal, usually referred to as sodium ion, a cation essential to the human body, excessive intake can cause some damage to the body. Sodium ion is a cation essential to the human body and is a major component of the osmotic pressure of extracellular liquid crystals, which plays an important role in various physiological functions of the body. Too much or too little serum sodium ion will cause certain damage to the body, will cause serious effects on the central nervous system, as well as the muscular system, gastrointestinal tract, such as apathy, headache, disorientation, nausea, vomiting, muscle spasms, and so on, and in severe cases, even lead to brain herniation and life. Sodium ions are commonly found in a variety of foods in nature, especially salty foods, which need to be consumed in moderation.