Skip to main content
ARS Home » Plains Area » Grand Forks, North Dakota » Grand Forks Human Nutrition Research Center » Healthy Body Weight Research » Research » Publications at this Location » Publication #96929
Title: INTERACTIONS AMONG DIETARY IRON, ZINC AND COPPER AFFECT IRON STATUS AND OXIDATIVE STRESS IN RATS: A RESPONSE SURFACE STUDY

Author
item Roughead, Zamzam
item JOHNSON, LUANN - UNIV OF NORTH DAKOTA
item Hunt, Janet

Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/26/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Although iron deficiency remains the number one single nutrient deficiency in the US and worldwide, there is some concern that an increase in body iron stores may increase oxidative stress which then may increase our risk of developing chronic diseases like heart disease, cancer and arthritis. Some scientists have warned that increased iron intake, which may be related to fortification of foods, may result in an undesirable increase in iron stores. However, the link between how much iron we eat, our iron stores and the risk of chronic disease is very controversial. Because of the substantial interactions between iron and other micronutrients, the intake of other elements also can play a role in changes in iron stores. This study was designed to examine the interactions among dietary iron, copper, and zinc and their effects on iron status and oxidative stress in rats. We fed several different diets with various (deficient to very high) amounts of iron, copper and zinc for 6 weeks. We found that iron status was mainly affected by how much iron the animals ate and not by the amounts of dietary zinc or copper. We also found that even though we fed the animals ten-fold as much iron as they needed, this did not cause oxidative stress. This much iron is well beyond the amounts people consume on a daily basis. Additionally, the animal's capacity to fight oxidative stress was mainly influenced by how much copper they ate and was optimal at moderate intakes of copper.

Technical Abstract: This study was designed to examine the interactions among dietary iron (Fe), copper (Cu), and zinc (Zn) and their effects on Fe status and oxidative stress in rats. In a three-factor central composite response surface design, rats were assigned to 15 groups and fed modified AIN-93G basal diets with varying amounts of Fe and Zn (7.0, 15.5, 45.8, 135.6, or 300 ug/g diet), and Cu (0.5, 1.1, 3.2, 9.2, or 20 ug/g diet) for 6 weeks. Variations in hemoglobin, hematocrit, and serum ferritin were mainly related to dietary Fe. Liver nonheme Fe was directly affected by dietary Fe and was slightly attenuated by interactions between Cu and Zn, and Zn and Fe. Serum ceruloplasmin activity was primarily determined by an interaction between Cu and Zn with substantial moderation by the quadratic effect of dietary Cu. Liver and heart total superoxide dismutase (SOD) and Cu/Zn SOD activities were directly affected by dietary Cu. Dietary Fe was the only significant, yet weak, predictor of liver thiobarbituric acid reactive substances (TBARS) and vitamin E content and serum triacylglycerols. Variability in serum Cu was mostly determined by the interaction between Cu and Fe with modification from the quadratic effect of dietary Cu. Serum Zn varied with dietary Zn with a small negative influence from the interaction between Cu and Fe. In summary, Fe status was minimally influenced by dietary Zn or Cu. Iron intakes ten-fold greater than required did not induce overt oxidative stress. In addition, measures of antioxidant capacity were primarily influenced by dietary Cu and were optimal at moderate intakes of this micronutrient.