Dietary fiber

Portion of plant-derived food that cannot be completely digested

Dietary fiber (also spelled fibre), or roughage, is the portion of plant-derived food that cannot be completely broken down by human digestive enzymes. Dietary fibers are diverse in chemical composition and can be grouped generally by their solubility, viscosity and fermentability, which affect how fibers are processed in the body. Dietary fiber has two main subtypes: soluble and insoluble.

From Wikipedia, under CC BY-SA. More on occurri.