ASPEN Certified Nutrition Support Clinician (CNSC) Practice Exam 2026 - Free CNSC Practice Questions and Study Guide

Soluble fiber slows upper GI transit because it dissolves in water and forms a viscous gel in the stomach. This gel increases chyme viscosity, which slows gastric emptying and the movement of contents into the small intestine. Insoluble fiber, on the other hand, adds bulk but doesn’t form gels, so it doesn’t meaningfully slow gastric emptying and may even pass through more quickly. Statements that there’s no fiber effect or that fiber speeds up upper GI transit don’t fit the way soluble fibers alter gastric emptying.