What is the main role of insoluble fiber in digestion?

The primary role of insoluble fiber in digestion is to act as a bulking agent, which helps to promote regular bowel movements and maintain gut health. Insoluble fiber does not dissolve in water and adds bulk to the stool, making it easier to pass through the digestive tract. This bulkiness stimulates the intestinal muscles, enhancing peristalsis—the wave-like muscle contractions that move food through the digestive system. By promoting efficient movement through the intestines, insoluble fiber plays a crucial role in preventing constipation and maintaining overall digestive health.

In contrast, while some forms of fiber can absorb nutrients, it is soluble fiber that is primarily responsible for that function. Insoluble fiber does not enhance flavor; rather, it is more about texture and fullness in foods. Additionally, breaking down carbohydrates is a function typically associated with enzymes rather than fiber. Thus, the correct answer highlights the essential function of insoluble fiber in maintaining the integrity and efficiency of the digestive process.