Milk is one of the oldest natural drinks and is known as "white blood". The importance of the human body can be imagined. Milk, as its name implies, is squeezed out of female cows. Milk is also available in different grades in different countries. Milk is rich in minerals, calcium, phosphorus, iron, zinc, copper, manganese and molybdenum. The most difficult thing is that milk is the best source of calcium in the body, and the ratio of calcium to phosphorus is very suitable, which is conducive to the absorption of calcium. The variety is complex, at least 100 kinds, the main ingredients are water, fat, phospholipids, protein, lactose, inorganic salts and so on. For the middle-aged and older people, milk has the great advantage that the cholesterol content in milk is lower than that of many animal protein cholesterol. It is worth mentioning that some ingredients in milk can also inhibit the amount of cholesterol produced by the liver, so that milk also has the effect of lowering cholesterol.