Cellulose is considered a complex carbohydrate because it is made up of long chains of glucose molecules linked together by beta-1,4-glycosidic bonds. Unlike simple carbohydrates, which consist of one or two sugar units (monosaccharides or disaccharides), complex carbohydrates, like cellulose, are polysaccharides, composed of numerous sugar units.
Cellulose has a unique structure that makes it difficult for many organisms to digest. It forms a rigid, fibrous structure that provides support to plant cells and is a primary component of plant cell walls. This complexity not only contributes to its stability but also influences how it interacts in biological systems.
Because of its intricate structure and the way it is broken down in the body (which requires specific enzymes that many organisms, including humans, lack), cellulose is categorized as a complex carbohydrate. Its role in our diet is significant, as it provides dietary fiber, which is essential for healthy digestion.