What is one of the main roles of dietary fiber?

Dietary fiber plays a crucial role in supporting gut health, which is essential for overall digestive function and maintaining a healthy microbiome. Fiber assists in regulating bowel movements by adding bulk to the stool, which helps prevent constipation. Additionally, certain types of soluble fiber can act as prebiotics, fostering the growth of beneficial bacteria in the gut. This contributes not only to better digestion but also to enhanced immune function and reduced risk for certain gastrointestinal diseases.

The other options reflect functions that are not primary roles of dietary fiber. Increasing appetite is more typically associated with macronutrients like carbohydrates and proteins rather than fiber. While fiber can contribute to a feeling of fullness, its role in appetite modulation is indirect. Providing energy is primarily the job of carbohydrates, proteins, and fats; fiber itself is not digested and thus does not provide usable calories. Lastly, aiding protein synthesis is a specific process related to amino acids and proteins and does not involve dietary fiber directly.