Dietary fiber is composed of compounds called lignins, which are found in the cell walls of plants and seeds, and complex carbohydrates extracted from plants or animal sources. No form of dietary fiber is digestible by human enzymes yet fiber has an important role in maintaining digestive and bowel health. Fiber is classified by its physiological effect as viscous and fermentable or nonviscous and nonfermentable. The Linus Pauling Institute notes that in simple terms dietary fiber is referred to as soluble or insoluble, although the physiological effects of fiber are best described by more complex classification. The term soluble fiber is used interchangeably with viscous and fermentable fiber.
Soluble Fiber Slows Digestion
Soluble fiber dissolves in water to form a gel. This form of fiber slows the passage of food through your intestines, but does not add bulk to fecal matter. Soluble fiber contains cellulose and hemicelluloses, sugars contained in plant cell walls. Soluble fibers are fermented in the intestines to aid in the formation of fatty acids like acetate, which is important in metabolizing nutrients to produce energy.
Regulates Bowels
Digestive disorders like irritable bowel syndrome are improved by regularly consuming soluble fiber. Constipation is a common symptom in IBS and consuming foods high in soluble fiber can significantly reduce its occurrence. In combination with insoluble fiber, which adds bulk to stool, soluble fiber intake can normalize bowel movements and improve bowel integrity, notes the Mayo Clinic. Increased soluble fiber intake and drinking at least 64 oz. of water daily can prevent and treat constipation.
Lowers Cholesterol and Improves Immunity
Soluble fiber is associated with reducing low-density lipoprotein, or bad, cholesterol levels. According to Colorado State University experts, soluble fiber binds to bile acids to excrete cholesterol from your body. This is significant as a tool for not only lowering high cholesterol but also protecting you from heart disease. The American Heart Association reports adding soluble fiber to your diet is more effective in lowering LDL cholesterol than lowering saturated fat intake alone. Preliminary animal studies conducted by researchers at the University of Illinois at Urbana-Champaign and reported on in the website Science Daily indicates that soluble fiber may increase your immune system health by acting as an anti-inflammatory when experiencing a bacterial infection. The study notes that regular daily intake of fiber is enough to induce this protective mechanism. However, claims of long-term immune boosting by use of soluble fiber is still undergoing clinical research.
Daily Recommendations and Food Sources
Daily fiber intake varies depending on your age and gender, but on average adults 50 years old and younger are recommended to consume a total of 25 g for women and 38 g for men. At least half of the dietary fiber daily total should be soluble fiber. Consult your physician to determine your exact daily fiber needs. Beans contain high amounts of soluble fiber, ranging from black beans at 2 g per half cup serving to lima beans with 3.5 g in the same serving size. Brussels sprouts has 3 g per half cup serving and citrus like oranges and grapefruit has 2 g in one medium sized fruit. One half cup of oatmeal or oatbran has 1 g per serving.
References
- Colorado State University: Dietary Fiber
- MayoClinic: Dietary Fiber: Essential for a Healthy Diet
- American Heart Association: Whole Grains and Fiber
- National Heart, Lung and Blood Institute: Food Sources of Soluble Fiber
- Science Daily: An Apple a Day? Study Shows Soluble Fiber Boosts Immune System
- Linus Pauling Institute: Fiber
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