D-Galacturonic acid is the main constituent of pectin, a naturally abundant compound. It is the monobasic acid resulting from oxidation of the primary alcohol group of D-galactose to carboxyl. D-Galacturonic acid prepared from pectin can be used to synthesize vitamin C. Native pectin is a mixture of polysaccharides, with the major component a polymer of -D-galacturonic acid. Pectin has numerous other medical and pharmaceutical uses, for example in combination with plant hemicelluloses and lignin, may be useful dietary constituents in preventing coronary heart disease, diverticular disease, ulcerative colitis, and a variety of other Western diseases. Pectin, a representative diety fibre, is a gelatinous substance derived from the cell walls of fruits and some plants and contains galacturonan, consisting of mostly long-chain D-galacturonic acids combined into units by α-1,4 linkages. As a kind of soluble dietary fiber, pectin has been proved of controlling glucose and blood lipids. It slows rapid infusion of the liquid meal into the gut by delaying gastric emptying.