The present invention provides an agent (a mucin generation promoter) having action that promotes the production of mucins in the intestinal tract and an agent (a fucosylation promoter) having action that promotes fucosylation in the intestinal tract, the agents being suitable for use in a food/beverage product (an intestinal-barrier-function-enhancing food product composition) for enhancing intestinal barrier function. The agents of the present invention are a mucin generation promoter characterized by containing yeast mannan, and a fucosylation promoter characterized by containing yeast mannan. The present invention also provides an intestinal-barrier-function-enhancing food product composition containing these agents.
