Magnesium supplementation in adults with marginal deficiency: response in blood indices, urine and saliva

Magnesium in plasma, erythrocyte, urine and saliva was measured before intervention, and at weekly intervals during two 28-d cycles of Mg supplementation in a group of 10 adults with marginal Mg deficiency (mean daily intake = 3.58 mg/kg). A group of untreated subjects with higher Mg intake (4.51 mg/kg) served as control. Urinary Mg excretion was correlated with Mg intake, and increased significantly by treatment. No difference was ascertained in plasma, except in subjects with the lowest Mg intake. Mg in erythrocytes was 10% lower in the deficient group, and reached values close to controls after 2 weeks of supplementation. Modifications in salivary Mg were also detected. The significance and usefulness of each index for clinical purpose are discussed.