The effect of dietary caffeine on urinary excretion of calcium, magnesium, phosphorus, sodium, potassium, chloride and zinc in healthy males

Abstract

Fifteen males drank decaffeinated coffee to which 0, 150 or 300 mg caffeine had been added. Each subject had fasted at least ten hours before drinking each of the three test beverages. Urine samples were collected at one, two and three hours after caffeine consumption. Total urinary three hour excretion of calcium, magnesium, sodium and chloride increased significantly after caffeine intake, while zinc, phosphorus, potassium, creatinine and volume were unchanged. The increased outputs were due to increased urinary mineral concentrations.