Lemons are rich in vitamin C, sugar, calcium, phosphorus, iron, vitamin B1, vitamin B2, niacin, quinic acid, citric acid, malic acid, hesperidin, naringin, coumarin, high potassium and low sodium, which is very beneficial to human' s bodies. Vitamin C can maintain the production of various tissues and intercellular substance, and maintain their normal physiological function. Vitamin C is needed to protect the parent material, adhesion and gelation in human body. When vitamin C is absent, intercellular stroma--the amount of gelatinous material decreases as following. In this way, the cell tissue will become brittle, and lose the ability to resist external forces. The human body will be prone to bad blood disease.