Effects of zinc intake on copper balance in adult females.

Adult women were fed dietary regimens that provided 2.0 mg of copper and either 8, 16, 24, mg of zinc daily in a 18-day controlled metabolic study. Zinc retentions were positive at all levels of intake, but the lowest level was probably not sufficient to maintain equilibrium. An intake of 16 mg of zinc was sufficient to maintain subjects in positive balance or at equilibrium, although this level may be marginal for individuals living in warm climates with potentially large sweat losses. None of the dietary groups was in positive balance on a copper intake of 2 mg/day, although the dietary level of zinc had no effect on copper retentions. Serum levels of copper decreased and zinc increased during the study.