Mannan is a water-soluble polysaccharide. It is a component of yeast cell-wall.

Mannans are known for their antimicrobial activity, prebiotic effect, emulsifying capacity and bioactivity. Mannans possess a wide range of biological activities that include cholesterol absorption and induction of hypocholesterolemia, induction of macrophage activation and interleukin-l release, inhibition of viral replication, wound healing, among others.