Magnesium’s role in preventing heart disease and strokes is generally well-accepted. Low magnesium (Mg) intake is also associated with increased incidence of diabetes mellitus, metabolic syndrome, and all-cause mortality. Historically it has generally been thought that easily ionized forms of magnesium like Mg citrate or aspartate are significantly better absorbed than magnesium salts like Mg oxide. However, a new study challenges that position.
In this double-blind study, researchers investigated the impact of supplemental oral Mg citrate versus Mg oxide on intracellular magnesium levels ([Mg2+]i) in healthy subjects. Healthy volunteers received either magnesium oxide tablets (520 mg/day of elemental magnesium) or magnesium citrate tablets (295.8 mg/day of elemental magnesium) for one month (phase 1), followed by a four-week wash-out period, and then crossover treatment for one month (phase 2). Using new analytical techniques (x-ray dispersion analysis) results showed Mg oxide produced a [Mg2+]i level of 36.3 mEq/L vs. 35.4 mEq/L for Mg citrate and reduced total and LDL cholesterol more significantly as well. Both forms also reduced platelet aggregation
Since the dosage of magnesium was also greater in the Mg oxide group, what these results indicate is that MG oxide as suitable of a form of magnesium as Mg citrate when given at larger dosage levels. Approximately 500 mg of Mg oxide may be equal to 350 mg Mg citrate.