Dietary nutrient intake affects calcium and magnesium metabolism

Previous studies suggested that sodium and potassium intake increase urinary calcium excretion. However, few studies of intake of nutrients initiating changes in calcium in plasma or saliva or magnesium in any other body fluid have been undertaken. We investigated intake of several nutrients, including sodium, potassium and phosphorus on calcium and magnesium metabolism in a controlled group of 253 subjects, 150 women and 103 men. Dietary intake was measured from records obtained for three typical days by use of Nutritionist Pro™. Calcium and magnesium levels were obtained in blood plasma, saliva and 24h urine collections and magnesium was obtained in erythrocytes. Each biological fluid was measured by flame aspiration atomic absorption spectrophotometry. As dietary sodium increased urinary calcium and magnesium increased. As dietary sodium increased there was a U shaped pattern in plasma calcium and magnesium with an initial increase followed by a decrease. As dietary potassium and phosphorus increased there was an increase in plasma calcium and magnesium and a decrease in salivary magnesium. These results indicate intake of dietary nutrients affect both calcium and magnesium metabolism. These results are important to understand how these nutrients affect metabolic control of calcium and magnesium in health and in disease.