Mannose commonly referred to as D-mannose. It exists in nature in the form of mannan. Free mannose is a colorless crystal Powder. Melting point 130°C (decomposition). The specific gravity is 1.539 (20/4°). Soluble in water, slightly soluble in ethanol, insoluble in ether. Crystals from the ethanol solution are rhombohedral or shuttle cylinders. Sweet and bitter. The sweetness is about 59% of sucrose. There are reducing and variable optical activity. The average abundance in marine plankton is second only to galactose and glucose. It exists as free sugars and bound sugars in solute, particulate matter and marine sediments of seawater. Mannose can be used in food, medicine, and other fields, and can be used as an additive for food and beverages. Some research data in the United States show that mannose is a kind of sugar with special curative effects, and it has good bactericidal and anti-inflammatory functions. It has very good adjuvant treatment effect on diabetes, obesity, constipation, high cholesterol, and other diseases.