title: Effect of transdermal magnesium cream on serum and urinary magnesium levels in humans: A pilot study.
abstract: BACKGROUND
  Oral magnesium supplementation is commonly used to support a low magnesium diet. This investigation set out to determine whether magnesium in a cream could be absorbed transdermally in humans to improve magnesium status.
  
  
  RESULTS
  In this single blind, parallel designed pilot study, n = 25 participants (aged 34.3+/-14.8y, height 171.5+/-11cm, weight 75.9 +/-14 Kg) were randomly assigned to either a 56mg/day magnesium cream or placebo cream group for two weeks. Magnesium serum and 24hour urinary excretion were measured at baseline and at 14 days intervention. Food diaries were recorded for 8 days during this period. Mg test and placebo groups' serum and urinary Mg did not differ at baseline. After the Mg2+ cream intervention there was a clinically relevant increase in serum magnesium (0.82 to 0.89 mmol/l,p = 0.29) that was not seen in the placebo group (0.77 to 0.79 mmol/L), but was only statistically significant (p = 0.02)) in a subgroup of non-athletes. Magnesium urinary excretion increased from baseline slightly in the Mg2+ group but with no statistical significance (p = 0.48). The Mg2+ group showed an 8.54% increase in serum Mg2+ and a 9.1% increase in urinary Mg2+ while these figures for the placebo group were smaller, i.e. +2.6% for serum Mg2+ and -32% for urinary Mg2+. In the placebo group, both serum and urine concentrations showed no statistically significant change after the application of the placebo cream.
  
  
  CONCLUSIONS
  No previous studies have looked at transdermal absorbency of Mg2+ in human subjects. In this pilot study, transdermal delivery of 56 mg Mg/day (a low dose compared with commercial transdermal Mg2+ products available) showed a larger percentage rise in both serum and urinary markers from pre to post intervention compared with subjects using the placebo cream, but statistical significance was achieved only for serum Mg2+ in a subgroup of non-athletes. Future studies should look at higher dosage of magnesium cream for longer durations.
  
  
  BACKGROUND
  ISRCTN registry ID No. ISRTN15136969.
authors.affiliation: University of Hertfordshire, Hatfield, Hertfordshire, United Kingdom.
authors.forename: Lindsy
authors.identifier: http://orcid.org/0000-0003-2079-4584
authors.initials: L
authors.lastname: Kass
authors.affiliation: Center for Magnesium Education & Research, Pahoa, Hawaii, United States of America.
authors.forename: Andrea
authors.initials: A
authors.lastname: Rosanoff
authors.affiliation: University of Hertfordshire, Hatfield, Hertfordshire, United Kingdom.
authors.forename: Amy
authors.initials: A
authors.lastname: Tanner
authors.affiliation: University of Hertfordshire, Hatfield, Hertfordshire, United Kingdom.
authors.forename: Keith
authors.initials: K
authors.lastname: Sullivan
authors.affiliation: University of Hertfordshire, Hatfield, Hertfordshire, United Kingdom.
authors.forename: William
authors.initials: W
authors.lastname: McAuley
authors.affiliation: Center for Magnesium Education & Research, Pahoa, Hawaii, United States of America.
authors.forename: Michael
authors.initials: M
authors.lastname: Plesset
mesh_terms: D000287:Administration, Topical; D000328:Adult; D005260:Female; D006801:Humans; D008274:Magnesium / Q000008:administration & dosage* / Q000493:pharmacokinetics; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D016037:Single-Blind Method; D063465:Skin Cream / Q000008:administration & dosage* / Q000493:pharmacokinetics; D055815:Young Adult
chemical_list: D008274:Magnesium