The circulating concentration and 24-h urine excretion of magnesium dose- and time-dependently respond to oral magnesium supplementation in a meta-analysis of randomized controlled trials

Xi Zhang, Liana C. Del Gobbo, Adela Hruby, Andrea Rosanoff, Ka He, Qi Dai, Rebecca B. Costello, Wen Zhang, Yiqing Song

Research output: Contribution to journalArticle

21 Scopus citations


Background: Accurate determination of Mgstatus is important for improving nutritional assessment and clinical risk stratification. Objective: We aimed to quantify the overall responsiveness of Mg biomarkers to oral Mg supplementation among adults without severe diseases and their dose- and time responses using available data from randomized controlled trials (RCTs). Methods: We identified 48 Mg supplementation trials (n = 2131) through searches of MEDLINE and the Cochrane Library up to November 2014. Random-effects meta-analysis was used to estimate weighted mean differences of biomarker concentrations between intervention and placebo groups. Restricted cubic splines were used to determine the dose- and time responses of Mg biomarkers to supplementation. Results: Among the 35 biomarkers assessed, serum, plasma, and urineMg were most commonlymeasured. ElementalMg supplementation doses ranged from 197 to 994 mg/d. Trials ranged from 3 wk to 5 y (median: 12 wk).Mg supplementation significantly elevated circulating Mg by 0.04 mmol/L (95% CI: 0.02, 0.06) and 24-h urine Mg excretion by 1.52 mmol/24 h (95% CI: 1.20, 1.83) as compared to placebo. Circulating Mg concentrations and 24-h urine Mg excretion responded to Mg supplementation in a dose- and time-dependent manner, gradually reaching a steady state at doses of 300 mg/d and 400 mg/d, or after ~20 wk and 40 wk, respectively (all P-nonlinearity ≤ 0.001). The higher the circulating Mg concentration at baseline, the lower the responsiveness of circulating Mg to supplementation, and the higher the urinary excretion (all Plinearity < 0.05). In addition, RBC Mg, fecal Mg, and urine calcium were significantly more elevated byMg supplementation than by placebo (all P-values < 0.05), but there is insufficient evidence to determine their responses to increasingMg doses. Conclusions: This meta-analysis of RCTs demonstrated significant dose- and time responses of circulating Mg concentration and 24-h urine Mg excretion to oral Mg supplementation.

Original languageEnglish (US)
Pages (from-to)595-602
Number of pages8
JournalJournal of Nutrition
Issue number3
StatePublished - Jan 1 2016



  • Circulating and urine Mg
  • Meta-analysis
  • Mg biomarkers
  • Mg status
  • Randomized controlled trial

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Nutrition and Dietetics

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