Nutritional fiber is more complex than it sounds. Physiologists have a list of different ways of classifying types of fiber, including dietary versus functional fiber, viscous vs. nonviscous fiber and soluble vs. insoluble fiber. The solubility of fiber was once thought to be a predictor of the physiological effects it induces in the human body, but the Linus Pauling Institute states that solubility is not an effective predictor of these effects.
What is Soluble Fiber?
Fiber is non-digestible carbohydrate. It passes through your gastrointestinal system in tact, and has no caloric value in the human digestive system. Soluble fibers are those that dissolve in water. Examples of soluble fiber include the beta-glucan found in oats. Other sources include pectin, which is found in apple pulp, and hemicellulose, which is found in beans, peas and lentils.
Solubility and Physiological Effects
Older schools of thought held that soluble fibers were more viscous, meaning that they formed gel-like substances in water. It was also believed that they were easier for your body's gastrointestinal flora to digest. Current thought on this appear to be mixed. The Linus Pauling Institute states that solubility is not necessarily an indicator of the viscosity or the fermentability of a particular type of fiber, while Medline Plus states that soluble fiber forms a gel during digestion.
Health Benefits of Soluble Fiber
Fiber aids the body in a number of ways. Jennifer Anderson of the Colorado State University Extension states that soluble fibers such as beta glucan and pectin have been found to decrease the levels of cholesterol in your blood. It is believed that soluble fiber increases bile acid production, which leads to increased cholesterol excretion. Soluble fiber may also be helpful in weight loss, as it adds no calories but helps you feel full and satiated.
Fiber Supplements
Soluble fiber is available in supplement form, but it is best to obtain it through wholesome dietary sources such as unprocessed fruits, vegetables and legumes. In doing so you reap the myriad of other nutritional benefits from healthy foods, without the risk of prescription drug interactions that may occur with fiber supplements. Consult your doctor before taking soluble-fiber supplements.
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