How does fiber differ from other complex carbohydrates?

Fiber is unique among complex carbohydrates because it serves primarily structural functions rather than energy storage. This structural role is evident in its presence in the cell walls of plants, where it helps maintain shape and rigidity. Unlike other complex carbohydrates, such as starches, which are broken down by the body to provide energy, fiber resists digestion in the gastrointestinal tract. This characteristic allows fiber to facilitate digestive health by adding bulk to the stool and promoting regular bowel movements.

The other options do not accurately reflect the nature of fiber. While some carbohydrates are easily digestible, fiber is not; it is intentionally resistant to enzymatic digestion. Additionally, fiber is not primarily used for energy storage, which is the role of carbohydrates such as glycogen and starch in the body. Lastly, describing fiber as having no nutritional value overlooks its essential role in digestive health, as well as its benefits in potentially reducing the risk of certain chronic diseases.