Short-term dietary magnesium restriction lowers spleen iron concentrations in growing rats fed a high-fat diet

•Short-term Mg restriction in high-fat-fed growing rats led to Fe redistribution.•High-fat did not influence serum and liver Fe, irrespective of dietary Mg level.•Significant associations were seen between body fat and serum and spleen Fe levels.•Dietary Mg adequacy should be considered in obese individuals with Fe dyshomeostasis.

Lipotoxicity and dietary inadequacies have been associated with dysregulation of Fe homeostasis in obesity. In this study, we tested the hypothesis that dietary Mg restriction in rats fed a high-fat diet affects Fe concentrations in liver and spleen, tissues related with Fe storage and recycling, respectively. Weanling male Wistar rats (n = 48) were fed either control (ad libitum or pair-fed) or high-fat (Mg-adequate or Mg-restricted; 500 and 150 mg Mg/kg, respectively) diets for 4 weeks. Epididymal and retroperitoneal fat pad weights were used to determine the adiposity index. Serum (colorimetry) and tissue Fe (atomic absorption spectrophotometry) were analyzed. Liver hepcidin was determined by qPCR and ferroportin-1 in liver and spleen was measured by immunoblotting. Dietary fat overload increased adiposity irrespective of dietary Mg levels. Rats fed the high-fat diet, but not those fed the high-fat Mg-restricted diet, had higher spleen Fe concentrations than controls. Weak but significant associations between body adiposity and serum (r = −0.31, P = 0.04) and spleen Fe (r = 0.29, P = 0.04) concentrations were obtained. The unaltered ferroportin-1 expression with low Fe levels suggests increased Fe recycling from spleen to bone marrow due to dietary Mg restriction. A longer study could clarify the consequences of these findings on erythropoiesis and other conditions related to diet-induced obesity.