Carbohydrates can be divided into several categories: monosaccharides, disaccharides and polysaccharides. Chemically speaking, the prefix before "saccharides" indicates how many saccharide chains are attached to the molecule. Polysaccharides have many chains and must be broken down into smaller portions before they can be fully digested. Although polysaccharides are a form of sugar, many of their food sources rarely taste sweet.
One example of a polysaccharide found in foods is starch. This is the main carbohydrate source for plant seeds and tubers, or vegetables that grow in the ground. Starch food sources often are referred to as "starchy carbohydrates" and include foods like corn, potatoes and rice. Other examples include bread, cereal and pasta. These foods are the most common form of carbohydrates in your diet, comprising an estimated one-third of the foods you eat. The body breaks starches down into glucose, which helps to give you energy.
Cellulose is another polysaccharide commonly found in foods. Cellulose provides a protective covering and/or structure to fruits and vegetables and their seeds. It gives foods a crunchy texture and is undigestible in the body. However, cellulose does act as a source of dietary fiber, adding bulk to your stool and helping to maintain regular digestive processes. Many fruits and vegetables contain some aspect of cellulose, including in the skins of apples and pears, in the covering of whole grains like wheat bran and in plant leaves like spinach. Seeds and nuts also contain cellulose.
Pectin is a compound that helps to form a gel-like substance when broken down in the body. Food sources that contain pectin also are known as soluble fiber sources. Soluble fiber is beneficial to the body because it prolongs stomach emptying, helping you to feel fuller, longer. Examples of soluble fiber include oats, dried beans, nuts, barley, flax seed, oranges, apples, carrots and psyllium husk.
Although starchy foods can get a bad reputation for being high-fat food sources, they contain fewer than half the calories of fats in your diet. They also are sources of fiber, calcium, iron and vitamins in your daily diet. To keep dietary polysaccharides as healthy options for you, cook your foods in healthy oils like olive or vegetable oils and avoid high-fat preparation methods like frying foods because such methods can offset the nutritional value of these foods.
- Rensselaer Polytechnic Institute; Carbohydrates - Sugars and Polysaccharides; Joyce Diwan; 2008
- Colorado State University; Dietary Polysaccharides: Structure and Digestion; R. Bowen; April 2006
- Britannica Online Encyclopedia; Polysaccharide; 2011
- Oregon State University Food Resource; Carbohydrates General; July 2009
- National Health Service; Starchy Foods - Live Well; March 2011
- HealthCastle.com; Fiber 101: Soluble Fiber vs. Insoluble Fiber; Gloria Tsang, RD; 2011