Functional fibers are isolated, nondigestible forms of carbohydrate that have been extracted from starchy foods or manufactured from starches or sugars. They may have some of the benefits of naturally occurring dietary fiber, such as helping to prevent constipation or lowering blood glucose levels after meals. But they lack the nutrients and phytochemicals that come with the fiber found in whole foods. On food labels, functional fibers are currently included in the grams of dietary fiber. Viscous fibers help to lower blood glucose and blood cholesterol levels, fermentable fibers are beneficial for colon health, and insoluble fibers help to alleviate constipation. Here are some of the more commonly used functional fibers:
- Beta-glucans may be extracted from oats, mushrooms, and yeast. They are viscous, fermentable soluble fibers.
- Cellulose is the main structural component of plant cell walls. Isolated cellulose may be derived from various sources, such as oat hulls, wheat, peas, soy, or cottonseed fiber. Cellulose is an insoluble fiber.
- Frucotooligosaccharides are fermentable fibers synthesized from sucrose.
- Guar gum is a viscous, fermentable fiber derived from the Indian cluster bean.
- Inulin is a fermentable fiber that may be synthesized from sucrose or extracted from chicory roots.
- Lignin is found in woody plant cell walls. It is insoluble.
- Oligofructose is a fermentable fiber that may be synthesized from sucrose or extracted from chicory roots.
- Pectins are viscous fibers most often extracted from citrus peels and apple pulp.
- Polydextrose is a chemical combination of glucose and sorbitol (a sugar alcohol) that is partially fermented in the large intestine.
- Psyllium is a viscous, soluble fiber isolated from the husks of psyllium seeds. It is commonly used in over-the-counter laxatives.
- Resistant maltodextrin is a fermentable fiber made by treating cornstarch with enzymes, heat, or acids.
