Association Between Dietary Intake of Magnesium With Blood Biomarkers

Objectives The purpose of this study was to investigate the relationship between dietary Mg intake and concentrations of ionized magnesium (iMg+2) in whole blood and total Mg in serum. Methods We evaluated blood iMg+2 concentration, the physiological active measure of Mg, as well as serum Mg concentration which is a more commonly used measure of body's status. The data study population were healthy participants (18–52 years; n = 23) who participated in three clinical visits in a magnesium supplement bioavailability study. All study participants were not taking Mg supplements within two weeks of study screening. Dietary Mg intake obtained from 3-day food records was compared with iMg+2 in whole blood and total Mg in serum concentrations using Pearson's correlations. Ionized magnesium was measured with NOVA 8 (NOVA Biochemical, Waltham, MA), serum Mg was measured with atomic absorption spectroscopy, and dietary intake of Mg was assessed using the Nutrition Data System for Research (NDSR; University of Minnesota, MN). Results were reported as means (standard deviations) and percentages for continuous and categorical data, respectively. Results Mean iMg+2 and serum Mg concentrations, and dietary Mg intake were 1.27 (0.07) mg/dL, 2.20 (5.0) mg/dL and 304.05 (128.77) mg/day, respectively. Results from the Pearson's correlation coefficient showed no significant association between dietary Mg intake vs. and serum Mg (r = −0.30, p = 0.23), nor was there a significant association between dietary Mg intake and iMg+2 (r = −0.08, p = 0.74). Conclusions Our findings suggest that iMg+2 and serum Mg concentrations may not reflect dietary Mg intake in a significant manner. Further research is needed to identify objective and accurate biomarkers that reflect dietary Mg intake, which will enable a better understanding of Mg deficiency and its association with conditions such as cardiovascular diseases, hypertension, diabetes, and chronic kidney disease. Funding Sources An unrestricted educational grant from New Capstone Inc., the manufacturer of ReMag®.

Effects of on-line hemodiafiltration regimens and dialysate composition on serum concentrations of magnesium and calcium ions

Background Low-ionized magnesium and high-ionized calcium levels are associated with increased cardiovascular mortality in patients undergoing dialysis. We examined the effects of the dilution method, substitution volume, and dialysate of on-line hemodiafiltration on the total and ionized magnesium and calcium levels. Methods Eighteen patients were randomly assigned to three dialysate groups: two acetic acid dialysate groups and one citrate dialysate group. Five treatment conditions were applied: pre-diluted on-line hemodiafiltration, post-diluted on-line hemodiafiltration, and hemodialysis. Results The total and ionized serum levels of magnesium and calcium were evaluated and found to be unaffected by the dilution methods and substitution volumes. The albumin leakage was approximately 3 g/session under the pre-dilution and hemodiafiltration conditions, and approximately 4–5 g/session under the post-dilution condition. The ionized magnesium concentration decreased in the citrate dialysate group. Conclusion The on-line hemodiafiltration parameters had a negligible effect on ionized magnesium and calcium; however, the use of citrate dialysate decreased the ionized magnesium levels, probably because of chelation. Trial registration 000028172. The study was registered on July 11 2017.