The polysaccharide cellulose is not digestible by humans, as we lack the enzyme cellulase, which is required to break it down. Certain dietary supplements contain the enzyme cellulase and claim that being able to break down cellulose will help a person lose weight. But what do you think would happen if we could digest the cellulose we ate?

Cellulose is a complex carbohydrate or polysaccharide that forms the structural component of the cell walls in green plants, algae, and some fungi. It is composed of long chains of glucose molecules linked by β-1,4-glycosidic bonds, making it resistant to digestion by humans due to the absence of the enzyme cellulase. While cellulose is not digestible, it serves as dietary fiber, promoting digestive health.

Enzymatic digestion refers to the biochemical process where enzymes break down complex molecules into simpler ones, facilitating nutrient absorption. In the case of cellulose, the enzyme cellulase is necessary to hydrolyze the β-glycosidic bonds, allowing the body to utilize the glucose units. Without this enzyme, cellulose passes through the digestive system largely intact, contributing to fiber intake rather than energy.

The claim that digesting cellulose could aid in weight loss hinges on the idea that breaking down this polysaccharide would provide additional calories. However, if humans could digest cellulose, it might lead to increased caloric intake without a corresponding increase in satiety, potentially resulting in weight gain rather than loss. Additionally, the role of fiber in promoting fullness and regulating appetite would be compromised.