A nutritional composition a lipid metabolism improving agent and prophylactic and/or therapeutic agents for inflammatory bowel disease immunopathy cancer non alcoholic steatohepatitis obesity diabetes hypercholesterolemia etc. each according to the present invention are characterized by containing a cellulose acetate that has a total degree of acetyl substitution of 0.4 1.1. The cellulose acetate may be a cellulose acetate that has a compositional distribution index (CDI) defined by the following formula of 2.0 or lower. CDI= (measured half compositional distribution width)/(theoretical half compositional distribution width) [wherein (measured half compositional distribution width) represents a value corresponding to a half compositional distribution width which is determined by an HPLC analysis of cellulose acetate propionate produced by propionylating all of remaining hydroxyl groups in cellulose acetate (a sample)]. In numerical formula (1) DS represents a total acetyl substitution degree and DPw represents a weight average polymerization degree that is determined by the GPC light scattering method using cellulose acetate propionate produced by propionylating all of remaining hydroxyl groups in cellulose acetate (a sample).
