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).L'invention concerne une composition nutritionnelle, un agent d'amélioration du métabolisme des lipides, ainsi que des agents prophylactiques et/ou thérapeutiques destinés aux infections inflammatoires du tube digestif, aux immunopathies, au cancer, à la stéatohépatite non alcoolique, à l'obésité, au diabète, à l'hypercholestérolémie, etc, chaque agent selon l'invention étant caractérisé en ce qu'il contient un acétate de cellulose présentant un degré total de substitution d'acétyle de 0,4 -1.1. L'acétate de cellulose peut être un acétate de cellulose possédant un indice de distribution de composition (CDI) défini par la formule suivante de 2,0 ou moins. CDI = (demi-largeur de distribution de composition mesurée)/ (demi-largeur de
