What is Dietary Fiber? Dietary fiber is a nutrient that is important for health, digestion, and disease prevention. It is a component of the total carbohydrates, which also includes sugars and starches. Dietary fiber consists of soluble and insoluble fiber. Soluble fiber contributes some calories due to its ability to dissolve in water and form a gelatinous substance that bacteria in the large intestine breaks down. Insoluble fiber does not provide calories since it’s not dissolved or ... Full Article