The objective of the study was to evaluate the efficacy of oral magnesium supplementation in the improvement of metabolic syndrome (MetS) and its components. This is a randomized double-blind, placebo-controlled clinical trial that enrolled 198 individuals with MetS and hypomagnesemia who were randomly allocated to receive either 30 mL of magnesium chloride 5% solution, equivalent to 382 mg of elemental magnesium (n = 100), or placebo solution (n = 98), daily for 16 weeks. Serum magnesium levels