Which statement best describes the mechanism by which unfermented dietary fiber affects stool water content?

Which statement best describes the mechanism by which unfermented dietary fiber affects stool water content?

• A. Unfermented fiber forms a gel that holds water, increasing stool water content
• B. Unfermented fiber is rapidly metabolized to short-chain fatty acids
• C. Unfermented fiber reduces stool water content
• D. Unfermented fiber passes through the GI tract unchanged

Answer: (A)

Unfermented, water-attracting fibers increase stool water content by forming a gel that holds onto water as it travels through the GI tract. This gel-like network吸 retains moisture, softening the stool and making it easier to pass. Since these fibers are not readily fermented in the colon, their effect on stool moisture comes from this physical water-holding property rather than fermentation products. In contrast, fibers that are rapidly metabolized produce short-chain fatty acids, and some fibers simply pass through with minimal interaction, so those ideas don’t explain the water-holding mechanism seen with unfermented fibers.

Unfermented, water-attracting fibers increase stool water content by forming a gel that holds onto water as it travels through the GI tract. This gel-like network吸 retains moisture, softening the stool and making it easier to pass. Since these fibers are not readily fermented in the colon, their effect on stool moisture comes from this physical water-holding property rather than fermentation products. In contrast, fibers that are rapidly metabolized produce short-chain fatty acids, and some fibers simply pass through with minimal interaction, so those ideas don’t explain the water-holding mechanism seen with unfermented fibers.