Magnesium Absorption in Humans
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Research Collection Doctoral Thesis Magnesium absorption in humans Author(s): Bohn, Torsten Publication Date: 2003 Permanent Link: https://doi.org/10.3929/ethz-a-004523459 Rights / License: In Copyright - Non-Commercial Use Permitted This page was generated automatically upon download from the ETH Zurich Research Collection. For more information please consult the Terms of use. ETH Library Diss. ETH No. 14930 Magnesium Absorption in Humans A dissertation submitted to the Swiss Federal Institute of Technology Zurich for the degree of Doctor of Natural Sciences presented by Torsten Bohn Staatlich geprüfter Lebensmittelchemiker University Frankfurt, Germany born 07.01.1972 citizen of Germany accepted on the recommendation of Prof. Dr. R.F. Hurrell, examiner Dr. L. Davidsson, co-examiner Dr. P. Kastenmayer, co-examiner 2003 Table of contents Acknowledgements ........................................................................................7 Summary..........................................................................................................9 Zusammenfassung .......................................................................................13 Introduction ...................................................................................................17 1. Literature review .......................................................................................20 1.1. Chemical properties of Mg and historical background ............................. 20 1.2. Mg in the human body.................................................................................. 21 1.2.1. Body partition of Mg................................................................................... 21 1.2.2. Physiological functions of Mg .................................................................... 23 1.2.3. Mg homeostasis......................................................................................... 24 1.2.3.1. Mg bioavailability, retention, status, and balance ................................. 24 1.2.3.2. Mg absorption....................................................................................... 25 1.2.3.3. Measuring Mg apparent and true absorption ........................................ 27 1.2.3.4. Mg excretion ......................................................................................... 27 1.2.3.5. Hormonal influences on Mg absorption and excretion.......................... 28 1.3. Mg and diet.................................................................................................... 30 1.3.1. Recommended dietary intake of Mg .......................................................... 30 1.3.2. Dietary Mg intake....................................................................................... 31 1.3.3. Mg content in food sources........................................................................ 33 2 1.4. Mg intake and Mg status and associations with health concerns............ 36 1.4.1. Osteoporosis.............................................................................................. 36 1.4.2. Diabetes mellitus type II............................................................................. 37 1.4.3. Cardiovascular diseases............................................................................ 39 1.4.4. Hypertension and stroke............................................................................ 41 1.5. Factors influencing Mg absorption ............................................................. 43 1.5.1. Overview.................................................................................................... 43 1.5.2. Physical factors.......................................................................................... 44 1.5.3. Type of Mg salt .......................................................................................... 45 1.5.4. Dietary factors influencing Mg absorption.................................................. 48 1.5.4.1. Proteins ................................................................................................ 48 1.5.4.2. Fat ........................................................................................................ 49 1.5.4.3. Dietary fibre and carbohydrates............................................................ 51 1.5.4.3.1. Insoluble fibre .................................................................................. 51 1.5.4.3.2. Soluble fibre..................................................................................... 53 1.5.4.3.2.1. Hemicellulose, pectin, and gums................................................ 54 1.5.4.3.2.2. Oligo(fructo)saccharides............................................................. 55 1.5.4.3.2.3. Resistant starch.......................................................................... 56 1.5.4.3.2.4. Lactose and lactulose................................................................. 58 1.5.4.4. Minerals and trace elements................................................................. 59 1.5.4.4.1. Calcium and phosphorus................................................................. 60 1.5.4.4.2. Sodium and potassium .................................................................... 62 1.5.4.5. Vitamin D .............................................................................................. 62 1.5.4.6. Phytic acid ............................................................................................ 63 1.5.4.7. Oxalic acid ............................................................................................ 66 3 1.5.4.8. Polyphenols .......................................................................................... 68 1.5.4.9. Chlorophyll............................................................................................ 69 1.6. Effects of dietary compounds on Mg excretion ......................................... 70 1.6.1. Ethanol ...................................................................................................... 70 1.6.2. Caffeine ..................................................................................................... 71 1.6.3. Anions and proteins ................................................................................... 72 1.7. Methods to study Mg absorption and metabolism .................................... 73 1.7.1. Overview.................................................................................................... 73 1.7.2. In vitro methods ......................................................................................... 74 1.7.3. Chemical balance technique...................................................................... 75 1.7.4. Extrinsic and intrinsic isotopic labels.......................................................... 76 1.7.5. Studies using radioactive isotopes............................................................. 79 1.7.6. Studies using stable isotopes .................................................................... 81 1.7.6.1. Overview............................................................................................... 81 1.7.6.2. Faecal monitoring to determine apparent Mg absorption...................... 86 1.7.6.3. Faecal monitoring for estimating true Mg absorption............................ 89 1.7.6.4. Urinary monitoring ................................................................................ 93 1.7.6.5. Tissue retention .................................................................................... 95 1.7.6.6. Plasma deconvolution method.............................................................. 97 1.7.7. Kinetic modelling........................................................................................ 99 1.7.8. Methods to determine Mg status.............................................................. 101 1.8. Use of stable isotope labels to determine Mg absorption....................... 102 1.8.1. Introduction.............................................................................................. 102 1.8.2. Quantification of Mg isotopic labels in a sample based on isotopic ratios 104 1.8.2.1. Single isotope techniques................................................................... 104 4 1.8.2.2. Double isotope techniques ................................................................. 106 1.8.3. Quantification of Mg isotopic labels in a sample based on isotopic abundabundances ............................................................................................. 109 1.8.3.1. Single isotope techniques................................................................... 109 1.8.3.2. Double isotope techniques ................................................................. 110 1.8.4. Sample preparation for Mg isotopic analysis ........................................... 112 1.8.5. Mg elemental analysis ............................................................................. 115 1.8.6. Mg isotopic analysis................................................................................. 116 1.8.7. Isotopic analysis by mass spectrometric techniques ............................... 117 1.8.7.1. Introduction......................................................................................... 117 1.8.7.2. Analytical techniques used for Mg isotopic analysis in the past.......... 119 1.8.7.3. TIMS................................................................................................... 120 1.8.7.4. ICP-MS ..............................................................................................