The effects of iron and zinc supplements on growth and on trace mineral parameters of young rats fed high levels of fiber were studied. The sources for fiber were Kellogg's all-bran, Quaker corn bran, Kellogg's Most, and Ener-G rice bran. Animals fed low and high levels of all-bran and corn bran diets not supplemented with iron or zinc had weight gains at the end of four weeks which were essentially the same as the weight gains of animals fed a non-cereal fiber control diet. Animals consuming diets containing Kellogg's Most exhibited the greatest weight gains, while animals consuming the rice bran cereal diet showed the least weight gains. Hemoglobin concentrations and concentrations of copper, iron, and zinc in the livers were essentially the same in all animals, regardless of the source of fiber. Iron or zinc supplements had no significant effects on hemoglobin or liver mineral deposition in animals fed all-bran cereal. In the absence of extra iron or zinc, animals consuming allbran, corn bran, and rice bran diets were in positive copper balance and negative iron balance. Animals fed Kellogg's Most were in negative copper balance and positive iron balance
