ABSTRACT
Metabolic Syndrome ......................................................................... 183 8.6 Physical Effects of Fiber Supplements in the Large Intestine ...................... 185
8.6.1 Large Bowel Effects: Fiber Benefits in Patients with Constipation and Diarrhea ................................................................ 186
8.6.2 Large Bowel Effects: Fiber Benefits in Patients with Irritable Bowel Syndrome ............................................................................... 188
While there is no globally-accepted definition of dietary fiber, the Institute of Medicine (IOM) developed the following set of working definitions for fiber in the food supply: “Dietary fiber consists of non-digestible carbohydrates and lignin that are intrinsic and intact in plants” [1]. Functional fiber consists of isolated, non-digestible carbohydrates that have beneficial physiological effects in humans. The isolated fibers found in the vast majority of dietary supplements would, therefore, be considered “functional fiber,” with the prerequisite of clinical evidence supporting the latter part of the statement, “… that have beneficial physiological effects in humans.” Consistent with these definitions, this chapter will focus on the health benefits of dietary fiber supplements, as evidenced by the physiologic effects observed in well-controlled clinical studies. Unlike prescription and over-the-counter medications, fiber supplements have no requirements for pre-market approval by the Food and Drug Administration (FDA), so it can be challenging to determine which fiber supplements have well-controlled clinical evidence to support specific health claims. It is, therefore, important to have a working knowledge of the physical characteristics of fiber that drive specific physiologic effects so as to accurately discern which products provide a clinically meaningful health benefit supported by published clinical data.
