What is subtance that cannot be digested?

The substance that cannot be digested is known as dietary fiber. It consists of plant-based carbohydrates that the human digestive system cannot break down. Fiber aids in digestion by promoting regular bowel movements and can help prevent constipation, but it passes through the digestive tract largely intact. There are two types of fiber: soluble and insoluble, both of which play important roles in maintaining health.