Retinol is a fat-soluble vitamin, which exists in animal food in the open form of free aldehydes or esters, and is rich in fat, protein, milk method and liver. There is no vitaminA in plants, but there is A precursor (provitaminA) of vitaminA, which is found in vegetables such as carrots and tomatoes. After absorption by animals, it can be converted into vitaminA. Retinol is essential for growth, development, reproduction and cell membrane stability, and plays an important role in the visual process. Retinaldehyde in the body due to continuous metabolism and supplement consumption, need to be timely through oxidative vitamin A supplement Chemicalbook charge. Vitamin A is related to the normal structure and function of upper and lower cells. Lack of vitamin A will lead to conjunctiva, cornea dryness, inflammation, and even blindness. It will also cause damage to respiratory epithelium, prone to respiratory infection, hair loss, infant growth retardation and so on. As A nutritional supplement, maintenance grade A oil is A fatty oil or its concentrate obtained from the liver and pyloric lobe of aquatic animals. Pulverize fresh fish liver and pylorus lobe, add 1-2% sodium hydroxide solution to ph8-9. Retinol can be used in sausage, margarine, bread, dairy products, fruit juice powder, peanut butter and so on.