Carbohydrate consists of three elements: carbon, hydrogen and oxygen. Because the ratio of hydrogen to oxygen is two to one, which is the same as water, it is called carbohydrate. It is the cheapest of the three main nutrients that provide heat energy for human body.

/iknow-pic . cdn . BCE Bos . com/0ff 4 1 BD 5 ad 6 eddc 495 c 486 BF 35 dbb 6 FD 52663356 " target = " _ blank " title = " " class = " ikqb _ img _ alink " & gt； /iknow-pic . cdn . BCE Bos . com/0ff 4 1 BD 5 ad 6 eddc 495 c 486 BF 35 dbb 6 FD 52663356？ x-BCE-process = image % 2f resize % 2Cm _ lfit % 2Cw _ 600% 2Ch _ 800% 2c limit _ 1% 2f quality % 2Cq _ 85% 2f format % 2Cf _ auto " esrc = "/ 0 ff 4 1 BD 5 ad 6 eddc 495 c 486 BF 35 dbb 6b 6 FD 52663356 "/>；

Carbohydrates in food can be divided into two categories: effective carbohydrates that people can absorb and utilize, such as monosaccharides, disaccharides, polysaccharides and ineffective carbohydrates that people can't digest, such as cellulose, which are essential substances for human body.

Before people know the chemical properties and composition of carbohydrates, carbohydrates have played a very good role. Now, plants rich in carbohydrates are used as food to make fermented drinks and animal feed. It was not until the18th century that a German scholar separated pure sugar from beet and glucose from grape that the research on carbohydrates developed rapidly.