What Is It?
Complex carbohydrates, primarily starches, are long chains of glucose molecules. These large glucose molecules are also known as polysaccharides which can be composed of various numbers of monosaccharides and disaccharides. Complex carbohydrates are polymers of simple sugars (monosaccharides) that are branched and may contain lipid or protein groups.
The three types of complex carbohydrates of nutritional importance are fiber, starch, and glycogen. Fiber refers to foods, mostly from plants, that the human body can not break down. Dietary fiber can be classified as soluble or insoluble. Examples of dietary fiber include beans, oatmeal, and the skins of fruits and vegetables. Starch, primarily found in grains, cereals, breads, and pastas, is the major source of carbohydrate in the diet. It is the storage form of carbohydrates in plants, comparable to glycogen in humans. Glycogen, commonly known as animal starch, is a starch-like substance in the liver and muscle tissue that is changed to glucose when it is needed for muscular work and for liberating heat. Glycogen represents the body’s carbohydrate stores. Glycogen is not counted as one of the complex carbohydrates in foods because it is not found in significant amounts in food.
Complex carbohydrates are important for several reasons. Starch and glycogen represent energy sources for the body while fiber has strong links to disease prevention.
Fiber is not a single substance, but represents a large group of different compounds with a variety of effects in the human body. However, all types of fiber are parts of plants that can not be digested by enzymes in the human intestinal tract. High fiber foods may be beneficial because they tend to be rich in antioxidants and low in fat and calories. A fiber rich diet is also beneficial in alleviating and preventing conditions including constipation, diverticulosis, colon and rectal cancer, heart disease, breast cancer, diabetes, and obesity.
David Edelberg, MD