Soluble fiber's effect on the upper GI tract includes which statement?

• A. Soluble fiber speeds gastric emptying
• B. Soluble fiber has no effect on gastric emptying
• C. Soluble fiber slows gastric emptying
• D. Soluble fiber delays intestinal transit only

Answer: (C)

Soluble fiber slows gastric emptying in the upper GI tract because it forms a viscous gel when mixed with water in the stomach. This gel increases the viscosity of the stomach contents, which dampens antral propulsion and mixing, causing chyme to move more slowly from the stomach into the small intestine. As a result, nutrient delivery to the small intestine is more gradual, helping to blunt postprandial glucose responses. So, stating that soluble fiber slows gastric emptying best captures its effect in the upper GI tract. It’s not about speeding emptying, and it isn’t accurate to say there’s no effect. While soluble fiber can influence intestinal transit later, the key upper-GI action is the delaying of gastric emptying.