Correlation between Mineral Intake and Urinary Excretion in Free-Living Japanese Young Women

To clarify whether the urinary excretion of calcium, magnesium, phosphorus, iron, zinc, copper, manganese, selenium and molybdenum can be used as an index of their intake, the association between urinary excretion and intake in free-living individuals was examined. A total of 102 healthy free-living female university dietetics students aged 18 33 years voluntarily participated in this study, of which 76 students were eligible for this assessment. All food consumed for four consecutive days was recorded accurately by a weighed food record method. A 24-h urine sample was collected on the fourth day, and the urinary levels of sodium, potassium, calcium, magnesium, phosphorus, iron, zinc, copper, manganese, selenium and molybdenum were measured. Significant correlation between urinary excretion and intake was observed in sodium (r = 0.596, p < 0.001), potassium (r = 0.583, p < 0.001), calcium (r = 0.402, p < 0.001), magnesium (r = 0.365, p < 0.01), phosphorus (r = 0.509, p < 0.001), selenium (r = 0.349, p < 0.01) and molybdenum (r = 0.265, p < 0.01). On the other hand, urinary excretion was very low and completely independent of the intake in iron, zinc, copper and manganese. These results indicate that urinary calcium, magnesium, phosphorus, selenium and molybdenum can be used as an index of their intake, similarly to sodium and potassium.