Influence of magnesium deficiency on the bioavailability and tissue distribution of iron in the rat

We investigated the effect of dietary magnesium (Mg) deficiency on the nutr itive utilization and tissue distribution of iron (Fe). Wistar rats were fe d an Mg-deficient diet (56 mg/kg) for 70 days. Absorbed Fe, Fe balance, num ber of the erythrocytes [red blood cells (RBC)] and leukocytes white blood cells (WBC)], hemoglobin (Hb), and Fe content were determined in samples of plasma, whole blood skeletal muscle, heart, kidney, liver, spleen, femoral bone, and sternum obtained on experimental days 21, 35, and 70. The Mg-def icient diet significantly increased Fe absorption and Fe balance from week 5 until the end of the experimental period. This effect was accompanied by a significant decrease in the concentration of RBC and Hb from day 35, whic h caused the decrease in whole blood Fe seen on day 70. However, WBC were s ignificantly increased from day 21 until the end of the experimental period Mg deficiency significantly increased plasma and fiver Fe at all three rim e points investigated Spleen, heart, and kidney Fe were significantly incre ased only at the end of the study. However, on Ray 70, Fe concentration in the sternum had decreased significantly. No changes were found in skeletal muscle or femur Fe content. Mg deficiency led to increased intestinal absor ption of Fe and decreased RBC counts, possibly us a result of increased fra gility of the erythrocytes. intestinal interactions between Fe and Mg, toge ther with activation of erythropoiesis as a result of hemolysis, favored in testinal absorption of Fe. This situation gave rise to an increase in plasm a Fe levels, which in turn favored Fe uptake and storage by different organ s, especially the liver and spleen. However despite the increased Fe conten t seen in the tissues of mts fed the Mg-deficient diet, these animals were unable to compensate for the hemolysis caused by this nutritional deficienc y. (J. Nutr. Biochem. 11:103-108, 2000) (C) Elsevier Science Inc. 2000. All rights reserved.