The present invention relates to a method of manufacturing a cereal bran product containing beta-glucan. According to the method, a plastic mass is formed from cereal bran by means of a thermo-mechanical treatment, and the mass is brought into contact with an enzyme that breaks up beta-glucan, with or without an enzyme that breaks up starch. After inactivating the enzyme, the bran is dried and, when so needed, ground. The cereal bran product manufactured according to the method has an essentially inextensible structure in a water environment. The product is suitable to be added to aqueous foodstuffs or to foodstuffs, the manufacture of which employs water.