Urological Research

, Volume 39, Issue 2, pp 123–127 | Cite as

Bioavailability of magnesium from different pharmaceutical formulations

  • Roswitha Siener
  • Andrea Jahnen
  • Albrecht Hesse
Original Paper


Magnesium is suggested to reduce intestinal oxalate absorption and to act as an inhibitor of calcium oxalate crystallization in the urine. However, previous studies have shown only minimal increase in urinary magnesium excretion following oral magnesium supplementation, possibly due to its low bioavailability. This study was performed to examine the bioavailability of magnesium from two different pharmaceutical formulations of magnesium oxide (MgO). Thirteen healthy male volunteers (22–31 years) were recruited from university students and staff, and all completed the study. During the baseline phase, subjects collected two 24-h urines while on their usual diet. Throughout the control and test phases, the subjects consumed a standardized diet calculated according to the recommendations. During the test phases, subjects received two magnesium preparations in a cross-over procedure. With each preparation, MgO-capsules and MgO-effervescent tablets, 450 mg magnesium was supplemented. On the control day and the two test days, fractional urine collection was performed and six corresponding blood samples were taken. In the follow-up phase, subjects continued to take the respective preparation while on their usual diet and collected 24-h urines weekly. With standardized conditions, urinary magnesium excretion increased by 40% after ingestion of the effervescent tablets, and by only 20% after intake of the capsules. The results indicate better bioavailability of magnesium from the effervescent tablets than from the capsules. This may be attributed to the fact that the tablets have to be dissolved in water before ingestion so that magnesium becomes ionized, which is an important precondition for absorption.


Magnesium oxide Urinary magnesium excretion Serum magnesium Hypomagnesuria Bioavailability Magnesium supplementation 


Conflict of interest

The authors declare that they have no conflict of interest.


  1. 1.
    Siener R, Schade N, Nicolay C, von Unruh GE, Hesse A (2005) The efficacy of dietary intervention on urinary risk factors for stone formation in recurrent calcium oxalate stone patients. J Urol 173:1601–1605PubMedCrossRefGoogle Scholar
  2. 2.
    Hesse A, Tiselius HG, Siener R, Hoppe B (2009) Urinary stones: diagnosis, treatment, and prevention of recurrence. 3rd revised and enlarged edition. Karger, BaselGoogle Scholar
  3. 3.
    Li MK, Blacklock NJ, Garside J (1985) Effects of magnesium on calcium oxalate crystallization. J Urol 133:123–125PubMedGoogle Scholar
  4. 4.
    Desmars JF, Tawashi R (1973) Dissolution and growth of calcium oxalate monohydrate. I. Effect of magnesium and pH. Biochim Biophys Acta 313:256–267PubMedGoogle Scholar
  5. 5.
    Voss S, Zimmermann DJ, Hesse A, von Unruh GE (2004) The effect of oral administration of calcium and magnesium on intestinal oxalate absorption in humans. Isotopes Environ Health Stud 40:199–205PubMedCrossRefGoogle Scholar
  6. 6.
    Liebman M, Costa G (2000) Effects of calcium and magnesium on urinary oxalate excretion after oxalate loads. J Urol 163:1565–1569PubMedCrossRefGoogle Scholar
  7. 7.
    Zimmermann DJ, Voss S, von Unruh GE, Hesse A (2005) Importance of magnesium in absorption and excretion of oxalate. Urol Int 74:262–267PubMedCrossRefGoogle Scholar
  8. 8.
    Melnick I, Landes RR, Hoffman AA, Burch JF (1971) Magnesium therapy for recurring calcium oxalate urinary calculi. J Urol 105:119–122PubMedGoogle Scholar
  9. 9.
    Prien EL, Gershoff SF (1974) Magnesium oxide-pyridoxine therapy for recurrent calcium oxalate calculi. J Urol 112:509–512PubMedGoogle Scholar
  10. 10.
    Johansson G, Backman U, Danielson BG, Fellström B, Ljunghall S, Wikström B (1982) Effects of magnesium hydroxide in renal stone disease. J Am Coll Nutr 1:179–185PubMedGoogle Scholar
  11. 11.
    Wilson DR, Strauss AL, Manuel MA (1984) Comparison of medical treatments for the prevention of recurrent calcium nephrolithiasis. Urol Res 12:39–40Google Scholar
  12. 12.
    Ettinger B, Citron JT, Livermore B, Dolman LI (1988) Chlorthalidone reduces calcium oxalate calculous recurrence but magnesium hydroxide does not. J Urol 139:679–684PubMedGoogle Scholar
  13. 13.
    Pearle MS, Roehrborn CG, Pak CYC (1999) Meta-analysis of randomized trials for medical prevention of calcium oxalate nephrolithiasis. J Endourol 13:679–685PubMedCrossRefGoogle Scholar
  14. 14.
    Tiselius HG, Ahlstrand C, Larsson L (1980) Urine composition in patients with urolithiasis during treatment with magnesium oxide. Urol Res 8:197–200PubMedCrossRefGoogle Scholar
  15. 15.
    Tiselius HG, Alken P, Buck C, Gallucci M, Knoll T, Sarica K, Türk C (2009) Guidelines on urolithiasis. European Association of Urology, The NetherlandsGoogle Scholar
  16. 16.
    Firoz M, Graber M (2001) Bioavailability of US commercial magnesium preparations. Magnes Res 14:257–262PubMedGoogle Scholar
  17. 17.
    Lindberg JS, Zobitz MM, Poindexter JR, Pak CYC (1990) Magnesium bioavailability from magnesium citrate and magnesium oxide. J Am Coll Nutr 9:48–55PubMedGoogle Scholar
  18. 18.
    Mühlbauer B, Schwenk M, Coram WM, Antonin KH, Etienne P, Bieck PR, Douglas FL (1991) Magnesium-l-aspartate-HCl and magnesium-oxide: bioavailability in healthy volunteers. Eur J Clin Pharmacol 40:437–438PubMedCrossRefGoogle Scholar
  19. 19.
    Walker AF, Marakis G, Christie S, Byng M (2003) Mg citrate found more bioavailable than other Mg preparations in a randomised, double-blind study. Magnes Res 16:183–191PubMedGoogle Scholar
  20. 20.
    Graham LA, Caesar JJ, Burgen ASV (1960) Gastrointestinal absorption and excretion of 28Mg in man. Metab Clin Exp 9:646–659Google Scholar
  21. 21.
    Quamme GA (1993) Magnesium homeostasis and renal magnesium handling. Miner Electrolyte Metab 19:218–225PubMedGoogle Scholar
  22. 22.
    Deutsche Gesellschaft für Ernährung, Österreichische Gesellschaft für Ernährung, Schweizerische Gesellschaft für Ernährungsforschung, Schweizerische Vereinigung für Ernährung (German, Austrian and Swiss Societies of Nutrition) (2000) Referenzwerte für die Nährstoffzufuhr (Reference values for nutrient intake). Umschau Braus, FrankfurtGoogle Scholar
  23. 23.
    Siener R, Jahnen A, Hesse A (2004) Influence of a mineral water rich in calcium, magnesium and bicarbonate on urine composition and the risk of calcium oxalate crystallization. Eur J Clin Nutr 58:270–276PubMedCrossRefGoogle Scholar
  24. 24.
    Siener R, Hesse A (1995) Influence of a mixed and a vegetarian diet on urinary magnesium excretion and concentration. Brit J Nutr 73:783–790PubMedCrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • Roswitha Siener
    • 1
  • Andrea Jahnen
    • 1
  • Albrecht Hesse
    • 1
  1. 1.Department of UrologyUniversity of BonnBonnGermany

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