Magnesium absorption from mineral water

We read with interest the paper of Verhas et al (2002), who studied magnesium (Mg) bioavailability from mineral water. The test was carried out on 300 ml of water containing 1.2 mmol of Mg. Using the radioisotope 28Mg, administered orally and intravenously on two separate sessions, Mg absorption (MgA) was estimated to be 59.113.6% (means.d.). We recently worked on the comparison of stable isotopic methods for MgA determination in men and have some comments to make regarding the method used by Verhas et al. Secondly, we would like to underline that MgA is mainly dose dependent, making comparisons between studies difficult.