Certified Dietary Manager (CDM) Practice Exam

What type of fiber is not soluble in water?

1. Soluble fiber

2. Insoluble fiber

3. Fermentable fiber

4. Functional fiber

The correct answer is: Insoluble fiber

Insoluble fiber is indeed the correct answer because it does not dissolve in water. Instead, it remains intact as it passes through the digestive system, adding bulk to stool and helping to promote regular bowel movements. This type of fiber is typically found in whole grains, nuts, seeds, and the skins of fruits and vegetables. Soluble fiber, in contrast, dissolves in water and can help manage blood sugar levels and lower cholesterol. Fermentable fiber is a subset of soluble fiber that can be fermented by gut bacteria, producing beneficial short-chain fatty acids. Functional fiber refers to fibers that have been extracted and are used for health benefits but can include both soluble and insoluble types. Thus, the distinction makes clear that insoluble fiber plays a vital role in digestive health, primarily through its ability to add bulk and promote regularity, which is why it is identified as a type of fiber that is not soluble in water.