a substantially odorless , refined fish oil product containing more than 20 % eicosapentaenoic acid as the fatty acid residue is provided . the product is produced by a process comprising combinations of steps of winterization of the oil , interesterification of the oil , deodorization procedure of the oil by heating thereof in vacuo with polyhydric alcohol and monoglyceride , and molecular distillation after the deodorization procedure . the product can be used mainly for prevention and therapy of thrombotic maladies by controlling the content of cholesterol in blood in humans .