Mycoprotein is the biomass of the fungus Fusarium venenatum. The ability of mycoprotein to enhance production of dialyzable iron following in-vitro digestion or extraction was studied, with the aim of identifying the components responsible. Digested mycoprotein, extracted mycoprotein and digested chicken breast muscle all produced about ten times as much dialyzable iron as the control. All of the dialyzable iron from mycoprotein was ferric. Essentially all the dialyzable iron passed through a 1 kDa molecular weight cut-off membrane. Iron binding components were extracted from mycoprotein using weak acid but not water. Extraction of mycoprotein produced both dialyzable and non-dialyzable components, which bound ferric iron. Analysis of the digests and the dialyzable fraction of acid extraction showed that they contained siderophores, which contributed to the formation of dialyzable iron.