Some aspects of the interpretation of mineral balances

Duncan, Dorothy L.

doi:10.1079/pns19670018

Cited by 9 publications

(1 citation statement)

References 14 publications

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“…Previous studies on this question, using the metabolic balance method, are inconclusive be-cause most reports used only a few subjects, because patients rather than normal subjects were sometimes studied, because the range of Mg intake was usually not systematically varied, and/or because the reports used balance periods that are too short for valid results. (A 3-wk balance period is required for methodologic accuracy [3,4].) Nevertheless, King and Stanbury pooled many previously reported metabolic balance studies, and showed that fecal Mg output was linearly correlated with Mg intake and that the regression line passed through zero (5).…”

Section: Introductionmentioning

confidence: 99%

Intestinal absorption of magnesium from food and supplements.

Fine¹,

Ana²,

Porter³

et al. 1991

J. Clin. Invest.

257

152

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The purpose of this study was to measure magnesium absorption over the wide range of intakes to which the intestine may be exposed from food and/or magnesium-containing medications. Net magnesium absorption was measured in normal subjects after they ingested a standard meal supplemented with 0, 10, 20, 40, and 80 mEq of magnesium acetate. Although absorption increased with each increment in intake, fractional magnesium absorption fell progressively (from 65% at the lowest to 11% at the highest intake) so that absorption as a function of intake was curvilinear. This absorption-intake relationship was almost perfectly represented by an equation containing a hyperbolic function plus a linear function. Our results are statistically compatible with a magnesium absorption process that simultaneously uses a mechanism that reaches an absorptive maximum, plus a mechanism that endlessly absorbs a defined fraction (7%) of ingested magnesium. Compared to previous studies of calcium absorption, much less magnesium than calcium was absorbed at intakes above 8 mEq/meal, apparently due to greater restriction of intestinal permeability to magnesium. We also found that magnesium from a high magnesiumcontaining food source, almonds, was just as bioavailable as from soluble magnesium acetate. In contrast, magnesium absorption from commercially available enteric-coated magnesium chloride was much less than from magnesium acetate, suggesting that enteric coating can impair magnesium bioavailability. (J. Clin. Invest. 1991.88:396-402.)

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Section: Introductionmentioning

confidence: 99%

Intestinal absorption of magnesium from food and supplements.

Fine¹,

Ana²,

Porter³

et al. 1991

J. Clin. Invest.

257

152

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Total Dietary Fiber and Mineral Absorption

Gordon

1990

Dietary Fiber

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Manganese in the nutrition and metabolism of the pullet

Mathers

Hill

1968

Br J Nutr

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1. Groups of pullets were given a diet of high (106–107 μg/g) or low (6–7 μg/g) manganese content and killed either before sexual maturity, at the point-of-lay or after a 6- to 7-month laying period. The birds were dissected into six tissue fractions: skeleton, liver, kidney, ovary and oviduct, skin and feathers, and muscle with remaining tissue. Total Mn and concentration of Mn as μg/g dry fat-free tissue were determined for each fraction.2. There were no differences in live weight attributable to level of dietary Mn, and no differences in egg production.3. Mean total body Mn varied among groups over a fairly narrow range (528–738 μg), with the exception of birds given the high-Mn diet throughout the experiment, in which the mean was 2319 μg. This represented an increase in Mn content during egg laying of 244%. There was no significant difference in the Mn content of birds given the low-Mn diet whether they were killed at the point-of-lay or after the laying period.4. The effects of treatment on the weight of Mn in each of the tissue fractions are described. The very large increase in total Mn that occurred during egg production in birds given the high-Mn diet was accounted for largely by the increase in skin and feathers (1072 μg Mn).5. In general terms, the Mn content of liver, kidney and ovary and oviduct together constituted only just over 10% of total body Mn, the remainder being distributed about equally among skeleton, skin and feathers, and muscle with remaining tissue.6. There was a close parallel between the concentration of Mn of a tissue and the total weight of Mn it contained except in certain instances when stage of maturity or egg production influenced weight of the tissue.7. The effects of treatments on the Mn contents of these birds are discussed in relation to the retention of dietary Mn, and the withdrawal from and accumulation of Mn in individual tissues and the whole body.

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Some aspects of the interpretation of mineral balances

Cited by 9 publications

References 14 publications

Intestinal absorption of magnesium from food and supplements.

Intestinal absorption of magnesium from food and supplements.

Total Dietary Fiber and Mineral Absorption

Manganese in the nutrition and metabolism of the pullet

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