Calcium and Magnesium Levels Change in Relationship to Variations in Usual Dietary Nutrient Intake

Abstract

Objective: Changes in nutrient intake induce changes in calcium and magnesium metabolism. However, studies dealing with these changes were usually performed by addition of one specific nutrient to initiate changes in either calcium or magnesium in only one biological fluid, usually blood plasma or urine. We were interested in evaluating changes in both calcium and magnesium levels in several biological fluids simultaneously in relationship to usual intake of a wide range of dietary nutrients since this type of study has not been previously performed. Methods: Calcium and magnesium in blood plasma, urine and saliva and magnesium in erythrocytes were measured by flame aspiration atomic absorption spectrophotometry in 253 subjects, 150 women and 103 men in relationship to their usual dietary intake of calcium, magnesium, sodium, potassium, phosphorus, carbohydrate, fat, fiber, protein, vitamin D, vitamin C and total calories. Dietary nutrient intake was calculated by careful, systematic analysis of all food and fluids taken over three typical days by performance of computer based dietary analysis. Results: Complex changes occurred in calcium and magnesium levels in some but not all biological fluids as usual dietary nutrient intake varied. As sodium, potassium and total calorie intake increased urinary calcium excretion increased. As sodium, potassium, vitamin D and protein intake increased urinary magnesium excretion increased. As sodium intake increased salivary magnesium decreased. Conclusions: These studies demonstrate that calcium and magnesium levels in blood plasma, urine, saliva and nasal mucus are altered following variations in the usual intake of several dietary nutrients. These results can assist in forming a nutritional foundation upon which variations in the usual dietary intake of several nutrients alter calcium and magnesium levels in several biological fluids.