Effect of Phosphorus on the Absorption of Calcium and on the Calcium Balance in Man1

Spencer, Herta; Kramer, Lois; Osis, Dace; Norris, C

doi:10.1093/jn/108.3.447

Cited by 147 publications

(33 citation statements)

References 22 publications

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“…However, investigators have found that the addition of 1200 mg P to a basal diet that contained 800 mg P had no effect on calcium absorption or balance, regardless of the amount of calcium in the diet (26). Thus, it seems unlikely that the increased amount of inorganic phosphorus in LPM will have undesirable metabolic consequences.…”

Section: Discussionmentioning

confidence: 99%

Effect of genetically modified, low–phytic acid maize on absorption of iron from tortillas

Mendoza

Viteri

Lönnerdal

et al. 1998

The American Journal of Clinical Nutrition

171

110

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Background: Genetically modified, low-phytic acid strains of maize were developed to enhance mineral absorption, but have not been tested previously in humans. Objectives: We evaluated the mineral and phytic acid contents of a low-phytic acid "flint" maize (LPM, the lpa-1-1 mutant) and its parent, wild-type strain (WTM) and measured iron absorption from tortillas prepared with each type of maize and from a reference dose of ferrous ascorbate. Design: Proximate composition and mineral and phytic acid contents were measured by standard techniques. Iron absorption from tortillas was evaluated by using the extrinsic tag method and was measured as the incorporation of radiolabeled iron into the red blood cells of 14 nonanemic men 2 wk after intake. Results: The phytic acid content of LPM was 3.48 mg/g, Ϸ35% of the phytic acid content of WTM; concentrations of macronutrients and most minerals were not significantly different between strains. Iron absorption results were adjusted to 40% absorption of ferrous ascorbate. Iron absorption was 49% greater from LPM (8.2% of intake) than from WTM (5.5% of intake) tortillas (P < 0.001, repeated-measures analysis of variance). Conclusion: Consumption of genetically modified, low-phytic acid strains of maize may improve iron absorption in human populations that consume maize-based diets.Am J Clin Nutr 1998;68:1123-7. KEY WORDSIron, iron absorption, iron deficiency, phytic acid, corn, maize, tortilla, men INTRODUCTIONNonheme iron from cereals and other plant sources is poorly absorbed because of the presence of inhibitors of iron absorption, such as phytic acid, tannins, and selected dietary fibers, which irreversibly bind iron in the intestinal lumen (1-3). One possible approach to improving iron absorption is to reduce the phytic acid content of foods by genetically modifying their capacity to synthesize phytic acid (4; V Raboy et al, unpublished observations, 1994). Recent experiments indicate that much of the phytic acid in maize and other cereals can be removed through genetic engineering without affecting the total phosphorus content of the grain or the health of the plant (V Raboy, K Young, P Gerbasi, unpublished observations, 1994). This offers great promise for human trace mineral nutrition, especially in populations that are primarily dependent on plantderived diets.Before promoting the large-scale production of low-phytic acid grain for human consumption, it is necessary that we determine whether a reduction in phytic acid content affects other components of the grain and whether low-phytic acid mutants do indeed have the expected effect on mineral absorption from mixed diets consumed by humans. We therefore conducted several laboratory analyses of the nutrient content of low-phytic acid and unmodified strains of maize and completed a clinical study of the effect of substituting the low-phytic acid maize on the absorption of nonheme iron from maize tortillas. The studies were conducted with maize tortillas because this is the most common form in which maize is ...

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Section: Discussionmentioning

confidence: 99%

Effect of genetically modified, low–phytic acid maize on absorption of iron from tortillas

Mendoza

Viteri

Lönnerdal

et al. 1998

The American Journal of Clinical Nutrition

171

110

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“…Second, the inhibitory effect of phosphate on Ca absorption may not occur for TBE. Ca balance studies in humans have demonstrated that phosphate has little effect on Ca absorption unless the Ca and phosphate intakes are both high (12). In this study, the amount of Ca present in the TBE ingested was 10.0mg.…”

Section: Discussionmentioning

confidence: 59%

Absorbability of Calcium from a New Calcium Supplement Prepared from Bovine Marrow-Free Bone in Rats.

Ohtani

Tsugawa

Kamao

et al. 1998

Journal of Nutritional Science and Vitaminology, J Nutr Sci Vit

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SummaryPowdered bovine marrow-free bone was completely sol ubilized with lactic and citric acids under reduced pressure. The resulting solution was lyophilized to obtain a stable powder form (total bone extract, TBE), and the calcium (Ca) absorbability of TBE from intestine was investigated in normal rats. Each animal perorally received 10mg of Ca in 1mL of distilled water as extrinsic 45Ca-labeled TBE, intrinsic 45Ca -labeled Ca lactate , or intrinsic 45Ca-labeled Ca carbonate. The amount of radioactivity in plasma was measured periodically up to 34 h after dosing, and pharmacokinetic parameters were calculated from the radioactivity in plasma. The time taken to reach the maximal 45Ca level (Tmax) did not differ among the three groups. The area under the plasma 45Ca level/time curve (AUCoo) and the radioactivity at Tmax (Cmax) values for the TBE group were significantly higher than those of the Ca carbonate group. Similar results were observed between the Ca lactate and the Ca carbonate groups. No significant difference was observed in the AUC co and the Cmax values between the TBE and the Ca lactate groups. Radioactivity in a femur 34h after dosing was highest in the Ca lactate group and lowest in the Ca carbonate group among the three groups. Both the TBE and the Ca lactate groups showed significant higher whole-body 45Ca retention than the Ca carbonate group did, although no significant difference was found between the TBE and the Ca lactate groups. These findings indicate that the Ca absorbability of TBE is almost comparable with that of Ca lactate and higher than that of Ca carbonate. Therefore TBE would be useful as a Ca supplement with relatively high absorbability from intestine.

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“…For instance, the groups receiving higher protein diets generally also consume higher amounts of dietary phosphorus. Dietary phosphorus has been found to mitigate protein-induced hypercalciuria (46,47,52,53). It is suggested that the high phosphorus content of most foodstuffs containing dietary protein may inhibit protein-induced hypercalciuria and bone loss (12,52).…”

Section: Discussionmentioning

confidence: 99%

Amino acid supplementation alters bone metabolism during simulated weightlessness

Zwart¹,

Davis-Street²,

Paddon‐Jones³

et al. 2005

Journal of Applied Physiology

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rando, R. R. Wolfe, and S. M. Smith. Amino acid supplementation alters bone metabolism during simulated weightlessness. J Appl Physiol 99: 134 -140, 2005. First published February 3, 2005 doi:10.1152/japplphysiol.01406.2004.-High-protein and acidogenic diets induce hypercalciuria. Foods or supplements with excess sulfurcontaining amino acids increase endogenous sulfuric acid production and therefore have the potential to increase calcium excretion and alter bone metabolism. In this study, effects of an amino acid/ carbohydrate supplement on bone resorption were examined during bed rest. Thirteen subjects were divided at random into two groups: a control group (Con, n ϭ 6) and an amino acid-supplemented group (AA, n ϭ 7) who consumed an extra 49.5 g essential amino acids and 90 g carbohydrate per day for 28 days. Urine was collected for n-telopeptide (NTX), deoxypyridinoline (DPD), calcium, and pH determinations. Bone mineral content was determined and potential renal acid load was calculated. Bone-specific alkaline phosphatase was measured in serum samples collected on day 1 (immediately before bed rest) and on day 28. Potential renal acid load was higher in the AA group than in the Con group during bed rest (P Ͻ 0.05). For all subjects, during bed rest urinary NTX and DPD concentrations were greater than pre-bed rest levels (P Ͻ 0.05). Urinary NTX and DPD tended to be higher in the AA group (P ϭ 0.073 and P ϭ 0.056, respectively). During bed rest, urinary calcium was greater than baseline levels (P Ͻ 0.05) in the AA group but not the Con group. Total bone mineral content was lower after bed rest than before bed rest in the AA group but not the Con group (P Ͻ 0.05). During bed rest, urinary pH decreased (P Ͻ 0.05), and it was lower in the AA group than the Con group. These data suggest that bone resorption increased, without changes in bone formation, in the AA group. bone resorption; methionine; n-telopeptide; acidosis; bed rest BONE LOSS AND FRACTURE RISK are significant concerns for astronauts and the general public. Diet can have a profound effect on acid-base balance of the body, which in turn could affect bone metabolism. Acid-base balance is determined mainly by the partial pressure of carbon dioxide and endogenous acid production from acid components in the diet (7, 21). Net endogenous acid production results from incomplete oxidation of organic acids and production of sulfuric acid by oxidation of sulfur-containing amino acids. In contrast, acid production can be neutralized by sources of bicarbonate in the diet or endogenous sources (7). Vegetables mainly provide base rather than acid precursors; they contain high concentrations of bicarbonate and other organic anions that can be converted to bicarbonate. Bicarbonate is one of the body's main buffering systems, and bone serves as a major body reservoir for bicarbonate (33).In vitro studies show that low pH induces bone resorption through a direct physiochemical effect as well as a cellular effect on bone (1). It is currently debated whether excess aci...

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Effect of Phosphorus on the Absorption of Calcium and on the Calcium Balance in Man1

Cited by 147 publications

References 22 publications

Effect of genetically modified, low–phytic acid maize on absorption of iron from tortillas

Effect of genetically modified, low–phytic acid maize on absorption of iron from tortillas

Absorbability of Calcium from a New Calcium Supplement Prepared from Bovine Marrow-Free Bone in Rats.

Amino acid supplementation alters bone metabolism during simulated weightlessness

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