How does fiber impact bowel elimination?

Fiber plays a crucial role in promoting healthy bowel elimination primarily by adding bulk to stools. This bulk makes it easier for stools to move through the digestive tract. When fiber is consumed, it absorbs water and swells, contributing to the formation of a gel-like substance that increases stool mass. This increased bulk stimulates intestinal contractions, which enhances peristalsis—the wave-like muscle contractions that move food through the digestive system. Consequently, regular consumption of fiber helps maintain regular bowel movements and can alleviate issues such as constipation.

The other options do not accurately reflect the positive roles that fiber plays in digestive health. For example, fiber does not decrease bowel movement frequency; rather, it encourages more regular and effective bowel movements. While fiber can slow the digestion of certain nutrients by binding to them, this is often beneficial for prolonging feelings of fullness and managing blood sugar levels, rather than indicating a negative impact. Additionally, fiber is not known for reducing nutrient absorption; in fact, it often helps with the overall balance of the digestive process. Therefore, the correct assertion about fiber is that it adds bulk to stools and facilitates their passage through the gastrointestinal tract.