Nonstarch polysaccharides aren't as complicated as they sound -- that term is just another name for a few types of fiber. What sets one carbohydrate apart from another is its size and structure, which in turn determines how, or if, it's digested. Nonstarch polysaccharides are large-sized carbs that aren't digested, but some are fermented once they reach the large intestine.
Simple carbohydrates consist of one or two units of sugar, or saccharide, while complex carbs contain three or more sugars linked together. Polysaccharides have at least 10 sugars and may have many thousands of sugar molecules. Starches are polysaccharides, but they're digestible because you have the enzymes needed to break the bonds between each sugar molecule. The human body doesn't have the enzymes required to cleave the type of bond holding polysaccharides together, so they're not digested. These nondigestable polysaccharides -- the nonstarch polysaccharides -- pass through your stomach and small intestine intact.
Different Groups and Types
Nonstarch polysaccharides come from plants, where they help form structural parts such as cell walls. The primary types of nonstarch polysaccharides are pectin, cellulose, gums and hemicelluloses. The hemicellulose group includes more than five different polysaccharides, including beta-glucan. Since nonstarch polysaccharides are types of fiber, they're further grouped according to the more commonly known types of fiber, soluble and insoluble. Cellulose falls into the insoluble group, which means it's the type of fiber that prevents constipation. Hemicelluloses, pectin and gums are all soluble fibers. They help lower cholesterol and keep blood sugar balanced. Most types of soluble fiber are also fermented by bacteria in the large intestine, a process that produces energy and short-chain fatty acids that promote intestinal health.
Best Food Sources
Vegetables are one of the best sources of cellulose. If you choose veggies with the highest amount of total fiber, such as broccoli, carrots, Brussels sprouts and green peas, you'll get the most cellulose because it accounts for a third of their total fiber. Fruits are the best-known sources of pectin, with apples, oranges and grapefruit at the top of the list. Fruits, vegetables, legumes and nuts also provide hemicelluloses. Oats are such good sources of beta-glucan that they're approved to carry a health claim stating that they can help reduce cholesterol, according to a report published in "Nutrition Reviews" in June 2011. Gums, such as guar gum and psyllium, are usually extracted from seeds and used as food additives or supplements.
Daily Intake Recommendations
If you need to lower cholesterol, you may want to boost the soluble fiber in your diet by consuming beans, peas, lentils and oats. Otherwise, just focus on getting the required daily intake for fiber rather than worrying about which type of fiber you consume. Even though some foods are better sources of one type of fiber, whole foods contain several types of soluble and insoluble fiber. If your diet includes a variety of vegetables, fruits, beans, whole grains and nuts, you will get all the different types. Women should consume 25 grams of total fiber daily, while men should aim for 38 grams.
- Comprehensive Reviews in Food Science and Food Safety: Nondigestible Oligo- and Polysaccharides (Dietary Fiber): Their Physiology and Role in Human Health and Food
- Institute of Medicine: Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids
- Elmhurst College: Cellulose
- Linus Pauling Institute: Fiber
- Columbia Health, Go Ask Alice!: Sources of Pectin (Soluble Fiber)
- Nutrition Reviews: Cholesterol-Lowering Effects of Oat Beta-Glucan
- Harvard University Health Services: Fiber Content of Foods in Common Portions