Certified Dietary Manager (CDM) Practice Exam

What characteristic defines soluble fiber?

1. Fiber that is high in protein

2. Fiber that forms a gel when combined with water

3. Fiber that is not digestible

4. Fiber found only in fruits

The correct answer is: Fiber that forms a gel when combined with water

Soluble fiber is specifically characterized by its ability to dissolve in water, forming a gel-like substance. This property allows soluble fiber to slow down digestion and absorption, which can help regulate blood sugar levels and lower cholesterol. Foods rich in soluble fiber include oats, nuts, beans, lentils, peas, and certain fruits and vegetables. While soluble fiber is not digestible in the traditional sense, as it cannot be broken down by the body, this is also true for all types of dietary fiber, including insoluble fiber. Therefore, while it's important to acknowledge that fiber is generally not digestible, it does not capture the unique characteristic of soluble fiber. Additionally, while fruits are indeed sources of soluble fiber, stating that it is only found in fruits is too limiting and does not encompass the broader range of food sources containing soluble fiber. Thus, the defining trait of forming a gel when combined with water best encapsulates the nature of soluble fiber.