Viscous versus nonviscous soluble fiber supplements: Mechanisms and evidence for fiber-specific health benefits

Purpose: This review focuses on the health benefits of viscous versus nonviscous soluble fibers, why symptoms can occur with increased fiber consumption, and how to avoid symptoms to improve adherence with a high-fiber diet. Data sources: Review of scientific literature as well as evidence-based guidelines and resources. Conclusions: While it is generally known that fiber is good for you, it is less well known that specific health benefits are associated with specific fiber characteristics. Many of the health benefits of fiber can be directly correlated with the viscosity of soluble fibers when hydrated (i.e., gel-forming). A reduction in viscosity of a given fiber will attenuate these health benefits, and a nonviscous fiber does not exhibit these health benefits. Implications for practice: Increasing the viscosity of chyme with a viscous soluble fiber has been shown clinically to lower cholesterol for cardiovascular health, improve glycemic control in type 2 diabetes, normalize stool form in both constipation (softens hard stool) and diarrhea (firms loose/liquid stool), and improve the objective clinical measures of metabolic syndrome (glycemic control, lipoprotein profile, body mass index/weight loss, and blood pressure).