Which fiber type specifically increases stool bulk and supports bowel regularity?

• A. Insoluble fiber adds bulk to stool and speeds intestinal transit.
• B. Soluble fiber slows gastric emptying and reduces postprandial glucose.
• C. Both types have identical effects on bowel regularity.
• D. Fiber has no effect on bowel regularity.

Answer: (A)

Insoluble fiber is the type that increases stool bulk and supports regularity. It resists digestion and passes largely intact through the small intestine, where it absorbs water and adds mass to the stool. That added bulk stretches the colon, stimulating its muscles and speeding transit, which helps prevent constipation and promotes regular bowel movements.

Soluble fiber, on the other hand, dissolves in water to form a gel-like substance. It tends to slow gastric emptying and can help with cholesterol and blood sugar management, and it can soften stool depending on the water it holds, but it does not primarily increase stool bulk.

So the statement that insoluble fiber adds bulk to stool and speeds intestinal transit best explains its role in promoting bowel regularity.