Comparison of calcium and magnesium absorption: in vivo and in vitro studies

Hardwick, Laurie L.; Jones, Michael R.; Buddington, Randal K.; Clemens, Roger; Lee, D. B.N.

doi:10.1152/ajpgi.1990.259.5.g720

Cited by 24 publications

(11 citation statements)

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“…In spite of this, the intestine seems to have a limited role in regulation of the Mg 2ϩ balance. In contrast to other minerals, intestinal Mg 2ϩ absorption is poorly regulated and depends mainly on Mg 2ϩ intake (216,461). Thus the kidneys presumably primarily regulate the maintainance of Mg 2ϩ homeostasis.…”

Section: A Magnesium In Intestinementioning

confidence: 99%

Magnesium in Man: Implications for Health and Disease

Baaij

Hoenderop

Bindels

2015

Physiological Reviews

1,285

1,299

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Section: A Magnesium In Intestinementioning

confidence: 99%

Magnesium in Man: Implications for Health and Disease

Baaij

Hoenderop

Bindels

2015

Physiological Reviews

1,285

1,299

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“…With a daily intake of 370 mg, the absorption rate of Mg 2+ in the intestine ranges from 30-50% [ 13 ]. However, the efficiency of Mg 2+ uptake is dependent on the ingested dose [ 15 , 16 ]. For example, early studies with a low dietary Mg 2+ intake showed that the relative absorption rate can reach 80% [ 17 ], whereas it is reduced to 20% with Mg 2+ surfeits [ 18 ].…”

Section: Mechanisms Of Mg2+ Absorption In the Intestinementioning

confidence: 99%

Intestinal Absorption and Factors Influencing Bioavailability of Magnesium- An Update

Schuchardt

Hahn

2017

CNF

148

110

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Background: Information on the bioavailability of the essential mineral Mg2+ is sparse.Objective/Method: Evaluation of the present knowledge on factors influencing the bioavailability and intestinal absorption of Mg2+.Results: Mg2+ is absorbed via a paracellular passive and a transcellular active pathway that involves TRPM6/7 channel proteins. The bioavailability of Mg2+ varies within a broad range, depending on the dose, the food matrix, and enhancing and inhibiting factors. Dietary factors impairing Mg2+ up-take include high doses of other minerals, partly fermentable fibres (e.g., hemicellulose), non-fermentable fibres (e.g., cellulose, lignin), phytate and oxalate, whereas proteins, medium-chain-triglycerides, and low- or indigestible carbohydrates (e.g., resistant starch, oligosaccharides, inulin, mannitol and lactulose) enhance Mg2+ uptake. The Mg2+ dose is a major factor controlling the amount of Mg2+ absorbed. In principle, the relative Mg2+ uptake is higher when the mineral is in-gested in multiple low doses throughout the day compared to a single, large intake of Mg2+. The type of Mg2+ salt appears less relevant than is often thought. Some studies demonstrated a slightly higher bioavailability of organic Mg2+ salts compared to inorganic compounds under standardized conditions, whereas other studies did not.Conclusion: Due to the lack of standardized tests to assess Mg2+ status and intestinal absorption, it remains unclear which Mg2+ binding form produces the highest bioavailability. The Mg2+ intake dose combined with the endogenous Mg2+ status is more important. Because Mg2+ cannot be stored but only retained for current needs, a higher absorption is usually followed by a higher excretion of the mineral.

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“…In the present experiment the highest plasma 25Mg enrichment was observed at about 4 h reaching 84 % and 144 % in rats receiving 6 or 12 mg 25Mg respectively. Others have also observed a peak of 28Mg 4 h after isotope administration in rats (Aikawa, 1981;Hardwick et al 1990b). The plasma and urine enrichment levels at 24 h (35 %, 54 %) and at 72 h (15 %, 20 %) respectively were sufficiently high to permit accurate isotopic measurements and their use to calculate several kinetic constants of Mg metabolism, particular1 if used in conjunction with intravenous administration of a second Mg stable isotope ( Mg) as in the next experiment.…”

Section: Single Labelling and Metabolic Balance Studymentioning

confidence: 95%

Study of magnesium bioavailability using stable isotopes and the inductively-coupled plasma mass spectrometry technique in the rat: single and double labelling approaches

et al. 1997

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The present work aimed to investigate the feasibility of using stable isotopes and inductively-coupled plasma mass spectrometry (ICP/MS) to study Mg absorption in rats. Male Wistar rats, aged 7 weeks and weighing 18Og, were used. They were fed on a semi-purified diet containing 1070mg Mg/kg, and had free access to feed and distilled water. In the first experiment, after a 16d adaptation period, two doses of enriched %g (6 and 12 mg) were administered by oral intubation, faeces and urine were collected daily and blood was sampled. Isotope ratios were determined by ICP/MS. 'True' absorption values, using the faecal isotope data, were 0.63 and 0-56 in rats receiving 6 and 12mg =Mg respectively, while apparent absorption was 0-50 for two successive periods of metabolic balance studies. Moreover, the oral isotope . ' * . ation resulted in a measurable isotopic enrichment in plasma within hours which was still detectable on the third day fdowing the isotope administration. In the second experiment, investigating the double labelling technique, similar rats were dosed Simultaneously with 5mg 26Mg orally (premixed with diet) and 0.29mg =Mg intravenously. The calculated Mg true absorption values were very similar when calculated from blood or urine data (0.38) but were lower than that obtained from faecal data (0.50). The possible causes of such an unexpected difference and limits of the double labelling technique for Mg absorption are discussed here. Together these results indicate that although =Mg and 26Mg isotopes have high natural abundance, the described methodology permits meaningful investigations of Mg bioavailability and metabolism. Magnesium: Absorption: Stable isotopes: Inductively-coupled plasma mass spectrometry Mg plays an essential role in a wide range of fundamental biological and cellular functions and it is not surprising that Mg deficiency may lead to serious biochemical and symptomatic changes (Durlach, 1988; Rayssiguier et al. 1993~). Recent studies indicate an important role of Mg deficiency in the aetiology of cardiovascular pathology (Rayssiguier et al. 1993b;Gueux et al. 1995). Such Mg deficiency may result from inadequate intake and/or impaired intestinal absorption of Mg. An extensive recent review (Hardwick et al. 1990~) discussed the intestinal sites of Mg absorption and it was the consensus that the primary site of Mg absorption is the distal intestine, the ileum (Phillips et al. 1991). However, little information about Mg absorption and metabolism is available. This lack of data is largely due to restrictions in the use of radioisotopes and methodological problems *For reprints.

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Comparison of calcium and magnesium absorption: in vivo and in vitro studies

Cited by 24 publications

References 0 publications

Magnesium in Man: Implications for Health and Disease

Magnesium in Man: Implications for Health and Disease

Intestinal Absorption and Factors Influencing Bioavailability of Magnesium- An Update

Study of magnesium bioavailability using stable isotopes and the inductively-coupled plasma mass spectrometry technique in the rat: single and double labelling approaches

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