Soluble Fiber


Soluble Fiber Helps Eliminate Cholesterol : This image shows a woman eating an apple - which contains soluble fiber. She has visible anatomy which focuses on the digestive tract. Soluble fiber acts like a cholesterol "sponge" by soaking up cholesterol-laden bile salts in the small intestine and eliminating these salts along with waste. Removing harmful cholesterol from the body decreases the amount of bad cholesterol collecting on the walls of the arteries, where it could increase the risk of heart attack and stroke. Soluble fiber can be found in a variety of grains, fruits, and vegetables.

Dietary fiber or roughage is the indigestible portion of food derived from plants. It has two main components:

  • Soluble fiber, which dissolves in water. It is readily fermented in the colon into gases and physiologically active byproducts, and can be prebiotic and viscous. Soluble fibers tend to slow the movement of food through the system.
  • Insoluble fiber, which does not dissolve in water. It can be metabolically inert and provide bulking, or it can be prebiotic and metabolically ferment in the large intestine. Bulking fibers absorb water as they move through the digestive system, easing defecation. Fermentable insoluble fibers mildly promote stool regularity, although not to the extent that bulking fibers do, but they can be readily fermented in the colon into gases and physiologically active byproducts. Insoluble fibers tend to accelerate the movement of food through the system.

Dietary fibers can act by changing the nature of the contents of the gastrointestinal tract and by changing how other nutrients and chemicals are absorbed. Some types of soluble fiber absorb water to become a gelatinous, viscous substance which is fermented by bacteria in the digestive tract. Some types of insoluble fiber have bulking action and are not fermented. Lignin, a major dietary insoluble fiber source, may alter the rate and metabolism of soluble fibers. Other types of insoluble fiber, notably resistant starch, are fully fermented.

Chemically, dietary fiber consists of non-starch polysaccharides such as arabinoxylans, cellulose, and many other plant components such as resistant starch, resistant dextrins, inulin, lignin, waxes, chitins, pectins, beta-glucans, and oligosaccharides. A novel position has been adopted by the US Department of Agriculture to include functional fibers as isolated fiber sources that may be included in the diet. The term "fiber" is something of a misnomer, since many types of so-called dietary fiber are not actually fibrous.

Food sources of dietary fiber are often divided according to whether they provide (predominantly) soluble or insoluble fiber. Plant foods contain both types of fiber in varying degrees, according to the plant's characteristics.

Advantages of consuming fiber are the production of healthful compounds during the fermentation of soluble fiber, and insoluble fiber's ability (via its passive hygroscopic properties) to increase bulk, soften stool, and shorten transit time through the intestinal tract.

A disadvantage of a diet high in fiber is the potential for significant intestinal gas production and bloating. Constipation can occur if insufficient fluid is consumed with a high-fiber diet.



The material on this site is for informational purposes only and is not intended as medical advice. It should not be used to diagnose or treat any medical condition. Consult a licensed medical professional for the diagnosis and treatment of all medical conditions and before starting a new diet or exercise program. If you have a medical emergency, call 911 immediately.