Complex Carbohydrates

"Complex carbohydrates are polysaccharides, or long chains of monosaccharides that may be branched or unbranched. The two main groups of polysaccharides are starches and fibers. Starch molecules are abundant in grains, legumes, and root vegetables such as potatoes. Amylose is a linear chain containing hundreds of glucose units, while amylopectin is a branched chain containing thousands of glucose units. These starch molecules form crystals and are the energy-storing molecules of plants. Cooking breaks down the crystal structure of starches, making them easier for the human body to digest. Starches that remain intact throughout digestion are called resistant starches; bacteria in the gut can break some of them down, which may benefit gastrointestinal health. Humans and animals store glucose energy from starches as glycogen, a very large molecule with many branches that allow it to break down quickly when energy is needed. Glycogen is found predominantly in liver and muscle tissue. Dietary fibers are polysaccharides that are highly branched and cross-linked. Examples include pectin, gums, cellulose, hemicellulose, and lignin, although lignin is not composed of carbohydrate units. Humans do not produce the enzymes that break down dietary fiber, but bacteria in the large intestine do. Diets high in fiber are supported by scientific evidence as reducing the risk of obesity and diabetes, which are primary risk factors for cardiovascular disease. Dietary fiber may be water-soluble or insoluble. Soluble fibers include inulin, pectin, and guar gum, while cellulose and lignin are insoluble fibers. Functional fibers are added to foods and have been shown to provide health benefits; psyllium-seed husk is an example. Total dietary fiber intake is the sum of dietary fiber and functional fiber consumed."