The common monosaccharides are fructose, glucose, galactose and ribose. Sugar is the main substance consumed by the body’s energy metabolism, however, disaccharides and polysaccharides need to be converted into monosaccharides in the small intestine in order to be absorbed by the body. 1. fructose: honey and fruits such as cherries and grapefruit contain fructose, and fructose is easily absorbed after being ingested by the body. In addition, fructose is also a food additive. 2. Glucose: It can be found in fruits such as grapes and watermelon, while glucose can be used to prepare solutions for a wide range of clinical applications, such as for the treatment of burns, hypoglycemia, and the inability to eat. The glucose in the blood is called blood sugar, which is also widely used in clinical applications, such as fasting blood sugar and postprandial blood sugar, and can be used to identify whether the subject is suffering from diabetes, hypoglycemia and other conditions; 3. Galactose: can be seen in some algae such as beets and Ulva lactuca, as well as milk, yogurt, cream, milk powder and other dairy products, in addition, it can also be seen in foods such as bread and pastries whose raw materials contain dairy products. For people who are lactose intolerant, it is necessary to consult a doctor before ingesting food containing galactose to clarify whether it can be ingested. In case of adverse reactions after accidental ingestion, medical attention is required. Monosaccharides are not limited to the above, but also include sulforaphane, xylose, lysose, etc. If eaten in moderation by a normal person, it does not cause special effects on the organism. However, if you are a diabetic, you should avoid eating it when your blood sugar is unstable, but even if such patients are stable, you should not eat a lot of it when you are taking your medication on time.