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Klatt KC, Smith ER, Barberio MD. Toward a more stable understanding of pregnancy micronutrient metabolism. Am J Physiol Endocrinol Metab 2021; 321:E260-E263. [PMID: 34151584 DOI: 10.1152/ajpendo.00156.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
There is an urgent need to better understand the micronutrient demands of pregnancy due to the complex physiological adaptations during the gestational period and the importance of micronutrients in maternal-fetal health. Rigorous studies of micronutrients in pregnancy are significantly lacking due to a number of issues including the exclusion of pregnant people in research, methodological barriers to studying micronutrients, and the multidisciplinary expertise required for such studies. Stable isotopes present a unique methodological opportunity to quantify pregnancy-related changes in the absorption, distribution, metabolism, and excretion of micronutrients. We demonstrate here through a rapid review of the published literature that this approach is dramatically underutilized outside of calcium. In this perspective, we discuss the use of stable isotopes to study micronutrient physiology and our experiences in addressing the need for more studies in this area. Finally, we discuss how we might overcome major barriers to move toward a better understanding of micronutrient physiology in pregnancy.
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Affiliation(s)
- Kevin C Klatt
- USDA/ARS Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas
| | - Emily R Smith
- Department of Global Health, Milken Institute School of Public Health, The George Washington University, Washington, District of Columbia
- Department of Exercise and Nutrition Sciences, Milken Institute School of Public Health, The George Washington University, Washington, District of Columbia
| | - Matthew D Barberio
- Department of Global Health, Milken Institute School of Public Health, The George Washington University, Washington, District of Columbia
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2
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Oral cinacalcet responsiveness in non-parathyroid hormone mediated hypercalcemia of malignancy. Med Hypotheses 2020; 143:110149. [DOI: 10.1016/j.mehy.2020.110149] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 07/20/2020] [Accepted: 07/28/2020] [Indexed: 02/06/2023]
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Duncan MW, Gale PJ. Vale Al Yergey. JOURNAL OF MASS SPECTROMETRY : JMS 2020; 55:e4535. [PMID: 32725946 DOI: 10.1002/jms.4535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
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Gale PJ, Duncan MW. Tools for quantitative analysis: The Al Yergey perspective. JOURNAL OF MASS SPECTROMETRY : JMS 2020; 55:e4524. [PMID: 32558000 DOI: 10.1002/jms.4524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 04/02/2020] [Indexed: 06/11/2023]
Abstract
The development of a reliable quantitative method for a specific application requires consideration of several important principles. Although mass spectrometry has become the "gold standard" for sensitive and precise multicomponent quantification, it does not necessarily follow that all quantitative data generated by mass spectrometry are either precise or accurate. Depending on the nature of the sample and the goal of the assay, the endeavor can be challenging. With attention to some critical concerns, valid results can be obtained; without attention to these concerns, results can be misleading and, in some instances, invalid. For almost 10 years, beginning in 1996, the authors of this article, together with their friend and colleague Al Yergey, taught an American Society for Mass Spectrometry (ASMS) Short Course on the principles of quantitative mass spectrometry. In this Special Feature, we revisit and update some of these principles. We pay special attention to the contributions of Al Yergey to the course that not only enriched our own understanding of quantitative analysis but also had a measurable impact on the entire field of mass spectrometry.
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Affiliation(s)
- P Jane Gale
- ASMS Archivist/Historian & Gale-Bentz Consulting, Southborough, Massachusetts, USA
| | - Mark W Duncan
- Target Discovery, Inc, Mountain View, California, USA
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Gale PJ, Cologna SM. Alfred L. Yergey III (September 17, 1941-May 27, 2018). JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2019; 30:557-560. [PMID: 30644054 DOI: 10.1007/s13361-018-2097-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Affiliation(s)
- P Jane Gale
- ASMS Archivist/Historian, Southborough, MA, USA.
| | - Stephanie M Cologna
- Assistant Professor, Department of Chemistry, University of Illinois at Chicago, Chicago, IL, USA
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Abrams SA, Griffin IJ, Herman S. Using Stable Isotopes to Assess the Bioavailability of Minerals in Food Fortification Programs. Food Nutr Bull 2018. [DOI: 10.1177/15648265020233s131] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The fortification of various types of food with minerals is often undertaken without consideration of either their bioavailability or the potential nutrient-nutrient interactions resulting from their use. Stable isotopes provide a safe and accessible method of resolving these issues by providing the proper evidence in each case. They must be conducted according to strict safety and ethical guidelines and may be readily conducted in a field setting. Clinical studies in children enable researchers, policymakers, and food manufacturers to obtain the data necessary to determine the best way to fortify specific foods and beverages, in order to optimally enhance the nutritional health of growing children. We have shown the utility of this approach in studies in both developing countries and in the United States.
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Affiliation(s)
- S. A. Abrams
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine in Houston, Texas, USA
| | - I. J. Griffin
- Nutrition Research and Development Center in Bogor, Indonesia
| | - S. Herman
- Nutrition Research and Development Center in Bogor, Indonesia
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Carrasco F, Basfi-Fer K, Rojas P, Csendes A, Papapietro K, Codoceo J, Inostroza J, Krebs NF, Westcott JL, Miller LV, Ruz M. Calcium absorption may be affected after either sleeve gastrectomy or Roux-en-Y gastric bypass in premenopausal women: a 2-y prospective study. Am J Clin Nutr 2018; 108:24-32. [PMID: 29878034 DOI: 10.1093/ajcn/nqy071] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 03/21/2018] [Indexed: 02/07/2023] Open
Abstract
Background Although Roux-en-Y gastric bypass (RYGBP) is known to reduce calcium absorption (CA), the effects of vertical sleeve gastrectomy (SG) and its long-term implications on CA have not yet been studied. Objective The aim of this study was to evaluate changes in CA and its relation with modifications of bone mineral density (BMD), intakes of calcium and vitamin D, vitamin D status, and parathyroid hormone (PTH) concentrations ≤24 mo after SG and RYGBP, respectively. Design Twenty-six premenopausal women undergoing SG [mean ± SD body mass index (BMI; kg/m2): 37.3 ± 3.2; age: 34.2 ± 10.2 y] and 32 undergoing RYGBP (BMI: 42.0 ± 4.2; age: 37.3 ± 8.1 y) were studied at baseline (presurgery) and followed up at 12 and 24 mo after surgery. BMD, bone alkaline phosphatase activity, and serum PTH, 25-hydroxyvitamin D [25(OH)D], calcium, magnesium, and phosphorus concentrations were determined. Food and supplement intakes were recorded. CA was measured by using a dual stable isotope method. Results In premenopausal women, CA was significantly reduced from 36.5% ± 2.0% preoperatively to 21.0% ± 2.3% and 18.8% ± 3.4% at 12 and 24 mo post-SG surgery, respectively. CA also decreased significantly from 41.5% ± 2.8% preoperatively to 27.9% ± 3.8% and 18.5% ± 2.2% 12 and 24 mo after RYGBP, respectively. No difference was found between type of surgery (time × group interaction, P = 0.60). Considering both groups combined, 56.6% of the variance in CA at the 12-mo but not at the 24-mo follow-up was explained by serum PTH and 25(OH)D concentrations, together with vitamin D and calcium intakes. Conclusions CA was similarly reduced in both SG and RYGBP compared with baseline, and it was not associated with changes in BMD or body weight loss. This reduction in CA could be explained only partially by calcium intake increase. This trial is registered at http://www.isrctn.com as ISRCTN31937503.
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Affiliation(s)
- Fernando Carrasco
- Department of Nutrition, Faculty of Medicine and Surgery, Clinical Hospital, University of Chile, Santiago, Chile
| | - Karen Basfi-Fer
- Department of Nutrition, Faculty of Medicine and Surgery, Clinical Hospital, University of Chile, Santiago, Chile
| | - Pamela Rojas
- Department of Nutrition, Faculty of Medicine and Surgery, Clinical Hospital, University of Chile, Santiago, Chile
| | - Attila Csendes
- Department of Surgery, Clinical Hospital, University of Chile, Santiago, Chile
| | - Karin Papapietro
- Department of Surgery, Clinical Hospital, University of Chile, Santiago, Chile
| | - Juana Codoceo
- Department of Nutrition, Faculty of Medicine and Surgery, Clinical Hospital, University of Chile, Santiago, Chile
| | - Jorge Inostroza
- Department of Nutrition, Faculty of Medicine and Surgery, Clinical Hospital, University of Chile, Santiago, Chile
| | - Nancy F Krebs
- Section of Nutrition, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO
| | - Jamie L Westcott
- Section of Nutrition, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO
| | - Leland V Miller
- Section of Nutrition, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO
| | - Manuel Ruz
- Department of Nutrition, Faculty of Medicine and Surgery, Clinical Hospital, University of Chile, Santiago, Chile
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Biasini B, Marchi L, Angelino D, Bedogni G, Zavaroni I, Pruneti C, Galli D, Mirandola P, Vitale M, Dei Cas A, Bonadonna RC, Passeri G, Ventura M, Del Rio D, Martini D. Claimed effects, outcome variables and methods of measurement for health claims on foods related to the gastrointestinal tract proposed under regulation (EC) 1924/2006. Int J Food Sci Nutr 2018; 69:771-804. [DOI: 10.1080/09637486.2018.1427220] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Beatrice Biasini
- Department of Food and Drugs, The Laboratory of Phytochemicals in Physiology, University of Parma, Parma, Italy
| | - Laura Marchi
- Department of Food and Drugs, The Laboratory of Phytochemicals in Physiology, University of Parma, Parma, Italy
| | - Donato Angelino
- Department of Food and Drugs, The Laboratory of Phytochemicals in Physiology, University of Parma, Parma, Italy
| | - Giorgio Bedogni
- Clinical Epidemiology Unit, Liver Research Center, Trieste, Italy
| | - Ivana Zavaroni
- Department of Medicine and Surgery, Division of Endocrinology, University of Parma, Parma, Italy
- Azienda Ospedaliera Universitaria of Parma, Parma, Italy
| | - Carlo Pruneti
- Department of Medicine and Surgery, Clinical Psychology Unit, University of Parma, Parma, Italy
| | - Daniela Galli
- Department of Medicine and Surgery, Sport and Exercise Medicine Centre (SEM), University of Parma, Parma, Italy
| | - Prisco Mirandola
- Department of Medicine and Surgery, Sport and Exercise Medicine Centre (SEM), University of Parma, Parma, Italy
| | - Marco Vitale
- Department of Medicine and Surgery, Sport and Exercise Medicine Centre (SEM), University of Parma, Parma, Italy
| | - Alessandra Dei Cas
- Department of Medicine and Surgery, Division of Endocrinology, University of Parma, Parma, Italy
- Azienda Ospedaliera Universitaria of Parma, Parma, Italy
| | - Riccardo C. Bonadonna
- Department of Medicine and Surgery, Division of Endocrinology, University of Parma, Parma, Italy
- Azienda Ospedaliera Universitaria of Parma, Parma, Italy
| | - Giovanni Passeri
- Department of Medicine and Surgery, Unit of Andrology, Metabolic Bone Diseases and Endocrinology, University of Parma, Parma, Italy
| | - Marco Ventura
- Department of Chemistry, Laboratory of Probiogenomics, Life Sciences and Environmental Sustainability, University of Parma, Parma, Italy
| | - Daniele Del Rio
- Department of Food and Drugs, The Laboratory of Phytochemicals in Physiology, University of Parma, Parma, Italy
| | - Daniela Martini
- Department of Food and Drugs, The Laboratory of Phytochemicals in Physiology, University of Parma, Parma, Italy
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Weber DR, O'Brien KO, Schwartz GJ. Evidence of disordered calcium metabolism in adolescent girls with type 1 diabetes: An observational study using a dual-stable calcium isotope technique. Bone 2017; 105:184-190. [PMID: 28882565 PMCID: PMC5650924 DOI: 10.1016/j.bone.2017.09.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 08/25/2017] [Accepted: 09/03/2017] [Indexed: 12/27/2022]
Abstract
Type 1 diabetes (T1D) is associated with skeletal abnormalities including low bone density and increased fracture risk. The pathophysiology underlying T1D related skeletal fragility remains unknown. The objective of this study was to use a dual-stable calcium isotope method to investigate the effects of T1D on calcium absorption and estimated calcium retention in adolescent females. Twenty adolescent females with T1D were admitted for a 24-h calcium absorption study using oral (44Ca) and intravenous (42Ca) stable isotopes for determination of percent gastrointestinal calcium absorption and estimated calcium retention. Five out of twenty participants were found to have negative estimated calcium retention. Participants with negative calcium retention had greater urinary calcium excretion [202mg/d (IQR: 178-213)] compared to those with positive calcium retention [101.5mg/d (IQR: 82-122)], p=0.01, but similar calcium intake and percent calcium absorption. With the exception of one outlier, 24-h urine calcium was significantly associated with hemoglobin A1c (Pearson's r=0.55, p=0.02). 50% of participants consumed less than the RDA for calcium; fractional calcium absorption was inversely correlated with calcium intake in participants not meeting the RDA (Spearman's rho -0.65, p=0.04). In conclusion, one-quarter of adolescent girls with T1D were found to have negative estimated calcium retention at a time when bone mineral accrual should be ongoing. This appeared to be the result of excess urinary calcium excretion as opposed to diminished gastrointestinal calcium absorption. Insufficient calcium availability for bone deposition during adolescence could impair bone mineral accrual and contribute to skeletal fragility. Trial registered: ClinicalTrials.gov Reg No. NCT03156179.
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Affiliation(s)
- David R Weber
- Department of Pediatrics, Golisano Children's Hospital, The University of Rochester School of Medicine and Dentistry, 601 Elmwood Ave, Box 690, Rochester, NY 14642, USA.
| | - Kimberly O O'Brien
- Division of Nutritional Sciences, Cornell University, 230 Savage Hall, Ithaca, NY, 14850, USA.
| | - George J Schwartz
- Department of Pediatrics, Golisano Children's Hospital, The University of Rochester School of Medicine and Dentistry, 601 Elmwood Ave, Box 690, Rochester, NY 14642, USA.
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10
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Kitay AM, Geibel JP. Stomach and Bone. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1033:97-131. [DOI: 10.1007/978-3-319-66653-2_6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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11
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Schafer AL, Weaver CM, Black DM, Wheeler AL, Chang H, Szefc GV, Stewart L, Rogers SJ, Carter JT, Posselt AM, Shoback DM, Sellmeyer DE. Intestinal Calcium Absorption Decreases Dramatically After Gastric Bypass Surgery Despite Optimization of Vitamin D Status. J Bone Miner Res 2015; 30:1377-85. [PMID: 25640580 PMCID: PMC4593653 DOI: 10.1002/jbmr.2467] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 01/04/2015] [Accepted: 01/26/2015] [Indexed: 12/13/2022]
Abstract
Roux-en-Y gastric bypass (RYGB) surgery has negative effects on bone, mediated in part by effects on nutrient absorption. Not only can RYGB result in vitamin D malabsorption, but the bypassed duodenum and proximal jejunum are also the predominant sites of active, transcellular, 1,25(OH)2 D-mediated calcium (Ca) uptake. However, Ca absorption occurs throughout the intestine, and those who undergo RYGB might maintain sufficient Ca absorption, particularly if vitamin D status and Ca intake are robust. We determined the effects of RYGB on intestinal fractional Ca absorption (FCA) while maintaining ample 25OHD levels (goal ≥30 ng/mL) and Ca intake (1200 mg daily) in a prospective cohort of 33 obese adults (BMI 44.7 ± 7.4 kg/m(2)). FCA was measured preoperatively and 6 months postoperatively with a dual stable isotope method. Other measures included calciotropic hormones, bone turnover markers, and BMD by DXA and QCT. Mean 6-month weight loss was 32.5 ± 8.4 kg (25.8% ± 5.2% of preoperative weight). FCA decreased from 32.7% ± 14.0% preoperatively to 6.9% ± 3.8% postoperatively (p < 0.0001), despite median (interquartile range) 25OHD levels of 41.0 (33.1 to 48.5) and 36.5 (28.8 to 40.4) ng/mL, respectively. Consistent with the FCA decline, 24-hour urinary Ca decreased, PTH increased, and 1,25(OH)2 D increased (p ≤ 0.02). Bone turnover markers increased markedly, areal BMD decreased at the proximal femur, and volumetric BMD decreased at the spine (p < 0.001). Those with lower postoperative FCA had greater increases in serum CTx (ρ = -0.43, p = 0.01). Declines in FCA and BMD were not correlated over the 6 months. In conclusion, FCA decreased dramatically after RYGB, even with most 25OHD levels ≥30 ng/mL and with recommended Ca intake. RYGB patients may need high Ca intake to prevent perturbations in Ca homeostasis, although the approach to Ca supplementation needs further study. Decline in FCA could contribute to the decline in BMD after RYGB, and strategies to avoid long-term skeletal consequences should be investigated.
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Affiliation(s)
- Anne L Schafer
- Department of Medicine, University of California, San Francisco, CA, USA
- Medical Service, San Francisco Veterans Affairs Medical Center, San Francisco, CA, USA
| | - Connie M Weaver
- Department of Nutrition Science, Purdue University, West Lafayette, IN, USA
| | - Dennis M Black
- Department of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA
| | - Amber L Wheeler
- Department of Medicine, University of California, San Francisco, CA, USA
- Medical Service, San Francisco Veterans Affairs Medical Center, San Francisco, CA, USA
| | - Hanling Chang
- Department of Medicine, University of California, San Francisco, CA, USA
- Medical Service, San Francisco Veterans Affairs Medical Center, San Francisco, CA, USA
| | - Gina V Szefc
- Medical Service, San Francisco Veterans Affairs Medical Center, San Francisco, CA, USA
| | - Lygia Stewart
- Department of Surgery, University of California, San Francisco, CA, USA
- Surgical Service, San Francisco Veterans Affairs Medical Center, San Francisco, CA, USA
| | - Stanley J Rogers
- Department of Surgery, University of California, San Francisco, CA, USA
| | - Jonathan T Carter
- Department of Surgery, University of California, San Francisco, CA, USA
| | - Andrew M Posselt
- Department of Surgery, University of California, San Francisco, CA, USA
| | - Dolores M Shoback
- Department of Medicine, University of California, San Francisco, CA, USA
- Medical Service, San Francisco Veterans Affairs Medical Center, San Francisco, CA, USA
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12
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Vreede AP, Jones AN, Hansen KE. Can serum isotope levels accurately measure intestinal calcium absorption compared to gold-standard methods? Nutr J 2015; 14:73. [PMID: 26227019 PMCID: PMC4520086 DOI: 10.1186/s12937-015-0065-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2015] [Accepted: 07/27/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Low fractional calcium absorption (FCA) contributes to osteoporosis but is not measured clinically, as the gold-standard method requires administration of two calcium tracers and a subsequent 24-h urine collection. We evaluated alternate methods to measure FCA, compared to the gold standard method. METHODS We administered two stable calcium isotope tracers (~8 mg oral (44)Ca and ~3 mg intravenous (42)Ca) with breakfast to 20 fasting post-menopausal women (Cohort 1) 59 ± 7 years old with vitamin D insufficiency. We measured subsequent calcium isotope concentrations in 24-h urine samples and serum collected 1, 3 and 5 h post tracer administration during an inpatient research stay. We assessed the candidate serum estimates in a second cohort of 9 women with similar characteristics. Methods of measuring FCA were compared using correlation coefficients and Bland-Altman tests. RESULTS FCA estimated from a 3-h serum sample correlated highest with the levels from the 24-h urine collection (ρ 0.78, p < 0.001), but explained only 58 % of the variance in FCA. The total variance explained by 3-h estimates improved to 61 % with incorporation of glomerular filtration rate (GFR). FCA estimates from the 3-h serum measurement were assessed in a second group of nine women (Cohort 2) 60 ± 7 years old. In this cohort, however, FCA estimated by 3-h serum isotope levels did not correlate with gold-standard FCA measurements, whether determined with (ρ 0.02, p = 0.97) or without GFR values (ρ 0.03, p = 0.93). By contrast, FCA in Cohort 2 correlated best with 5-h serum isotope levels (ρ 0.75, p = 0.02). CONCLUSIONS We conclude that serum isotope levels correlate with true fractional calcium absorption, but do not reliably estimate FCA when analyzed using Bland-Altman tests, compared to gold-standard methods. TRIAL REGISTRATION ClinicalTrials.gov.Identifier: NCT00933244.
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Affiliation(s)
- Andrew P Vreede
- Department of Medicine, University of Wisconsin School of Medicine & Public Health, Suite 4124 MFCB, 1685 Highland Avenue, Madison, WI, 53705-2281, USA.
| | - Andrea N Jones
- Department of Pediatrics, University of Wisconsin School of Medicine & Public Health, Madison, USA.
| | - Karen E Hansen
- Department of Medicine, University of Wisconsin School of Medicine & Public Health, Suite 4124 MFCB, 1685 Highland Avenue, Madison, WI, 53705-2281, USA.
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Shagina NB, Tolstykh EI, Degteva MO, Anspaugh LR, Napier BA. Age and gender specific biokinetic model for strontium in humans. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2015; 35:87-127. [PMID: 25574605 DOI: 10.1088/0952-4746/35/1/87] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A biokinetic model for strontium in humans is necessary for quantification of internal doses due to strontium radioisotopes. The ICRP-recommended biokinetic model for strontium has limitations for use in a population study, because it is not gender specific and does not cover all age ranges. The extensive Techa River data set on (90)Sr in humans (tens of thousands of measurements) is a unique source of data on long-term strontium retention for men and women of all ages at intake. These, as well as published data, were used for evaluation of age- and gender-specific parameters for a new compartment biokinetic model for strontium (Sr-AGe model). The Sr-AGe model has a similar structure to the ICRP model for the alkaline earth elements. The following parameters were mainly re-evaluated: gastrointestinal absorption and parameters related to the processes of bone formation and resorption defining calcium and strontium transfers in skeletal compartments. The Sr-AGe model satisfactorily describes available data sets on strontium retention for different kinds of intake (dietary and intravenous) at different ages (0-80 years old) and demonstrates good agreement with data sets for different ethnic groups. The Sr-AGe model can be used for dose assessment in epidemiological studies of general populations exposed to ingested strontium radioisotopes.
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Affiliation(s)
- N B Shagina
- Urals Research Center for Radiation Medicine, Chelyabinsk 454076, Russia
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14
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Vaisman N, Shaltiel G, Daniely M, Meiron OE, Shechter A, Abrams SA, Niv E, Shapira Y, Sagi A. Increased calcium absorption from synthetic stable amorphous calcium carbonate: double-blind randomized crossover clinical trial in postmenopausal women. J Bone Miner Res 2014; 29:2203-9. [PMID: 24753014 DOI: 10.1002/jbmr.2255] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 03/23/2014] [Accepted: 04/02/2014] [Indexed: 11/11/2022]
Abstract
Calcium supplementation is a widely recognized strategy for achieving adequate calcium intake. We designed this blinded, randomized, crossover interventional trial to compare the bioavailability of a new stable synthetic amorphous calcium carbonate (ACC) with that of crystalline calcium carbonate (CCC) using the dual stable isotope technique. The study was conducted in the Unit of Clinical Nutrition, Tel Aviv Sourasky Medical Center, Israel. The study population included 15 early postmenopausal women aged 54.9 ± 2.8 (mean ± SD) years with no history of major medical illness or metabolic bone disorder, excess calcium intake, or vitamin D deficiency. Standardized breakfast was followed by randomly provided CCC or ACC capsules containing 192 mg elemental calcium labeled with 44Ca at intervals of at least 3 weeks. After swallowing the capsules, intravenous CaCl2 labeled with 42Ca on was administered on each occasion. Fractional calcium absorption (FCA) of ACC and CCC was calculated from the 24-hour urine collection following calcium administration. The results indicated that FCA of ACC was doubled (± 0.96 SD) on average compared to that of CCC (p < 0.02). The higher absorption of the synthetic stable ACC may serve as a more efficacious way of calcium supplementation.
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Affiliation(s)
- Nachum Vaisman
- The Unit of Clinical Nutrition, Tel-Aviv Sourasky Medical Center, Tel-Aviv, Israel
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15
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Hansen KE, Nabak AC, Johnson RE, Marvdashti S, Keuler NS, Shafer MM, Abrams SA. Isotope concentrations from 24-h urine and 3-h serum samples can be used to measure intestinal magnesium absorption in postmenopausal women. J Nutr 2014; 144:533-7. [PMID: 24500940 PMCID: PMC3952625 DOI: 10.3945/jn.113.186767] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Studies suggest a link between magnesium status and osteoporosis. One barrier to more conclusive research on the potential relation is measuring intestinal magnesium absorption (MgA), which requires the use of stable isotopes and a ≥6-d stool or 3-d urine collection. We evaluated alternative methods of measuring MgA. We administered 2 stable magnesium isotopes to 15 postmenopausal women (cohort 1) aged 62 ± 8 y with a dietary magnesium intake of 345 ± 72 mg/d. Participants fasted from 1200 h to 0700 h and then consumed breakfast with ∼23 mg of oral ²⁶Mg and ∼11 mg of i.v. ²⁵Mg. We measured magnesium isotope concentrations in 72-h urine, spot urine (36, 48, 60, and 72 h), and spot serum (1, 3, and 5 h) samples collected after isotope dosing. We calculated MgA using the dose-corrected fraction of isotope concentrations from the 72-h urine collection. We validated new methods in 10 postmenopausal women (cohort 2) aged 59 ± 5 y with a dietary magnesium intake of 325 ± 122 mg/d. In cohort 1, MgA based on the 72-h urine collection was 0.28 ± 0.08. The 72-h MgA correlated most highly with 0-24 h urine MgA value alone (ρ = 0.95, P < 0.001) or the mean of the 0-24 h urine and the 3-h (ρ = 0.93, P < 0.001) or 5-h (ρ = 0.96, P < 0.001) serum MgA values. In cohort 2, Bland-Altman bias was lowest (-0.003, P = 0.82) using means of the 0-24 h urine and 3-h serum MgA values. We conclude that means of 0-24 h urine and 3-h serum MgA provide a reasonable estimate of 72-h MgA. However, if researchers seek to identify small changes in MgA, we recommend a 3-d urine or extended stool collection.
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Affiliation(s)
- Karen E. Hansen
- Department of Medicine, School of Medicine and Public Health,To whom correspondence should be addressed. E-mail:
| | | | | | | | | | - Martin M. Shafer
- Environmental Chemistry and Technology and Wisconsin State Laboratory of Hygiene, University of Wisconsin, Madison, WI; and
| | - Steven A. Abrams
- USDA/Agricultural Research Service Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX
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Moseley KF, Weaver CM, Appel L, Sebastian A, Sellmeyer DE. Potassium citrate supplementation results in sustained improvement in calcium balance in older men and women. J Bone Miner Res 2013; 28:497-504. [PMID: 22991267 PMCID: PMC3578058 DOI: 10.1002/jbmr.1764] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 08/22/2012] [Accepted: 09/04/2012] [Indexed: 11/09/2022]
Abstract
The dietary acid load created by the typical Western diet may adversely impact the skeleton by disrupting calcium metabolism. Whether neutralizing dietary acid with alkaline potassium salts results in sustained improvements in calcium balance remains controversial. In this randomized, double-blind, placebo-controlled study, 52 men and women (mean age 65.2 ± 6.2 years) were randomly assigned to potassium citrate 60 mmol/d, 90 mmol/d, or placebo daily with measurements of bone turnover markers, net acid excretion, and calcium metabolism, including intestinal fractional calcium absorption and calcium balance, obtained at baseline and at 6 months. At 6 months, net acid excretion was significantly lower in both treatment groups compared to placebo and it was negative, meaning subjects' dietary acid was completely neutralized (-11.3 mmol/d on 60 mmol/d; -29.5 mmol/d on 90 mmol/d, p < 0.001 compared to placebo). At 6 months, 24-hour urine calcium was significantly reduced in persons taking potassium citrate 60 mmol/d (-46 ± 15.9 mg/d) and 90 mmol/d (-59 ± 31.6 mg/d) compared with placebo (p < 0.01). Fractional calcium absorption was not changed by potassium citrate supplementation. Net calcium balance was significantly improved in participants taking potassium citrate 90 mmol/d compared to placebo (142 ± 80 mg/d on 90 mmol/d versus -80 ± 54 mg/d on placebo; p = 0.02). Calcium balance was also improved on potassium citrate 60 mmol/d, but this did not reach statistical significance (p = 0.18). Serum C-telopeptide decreased significantly in both potassium citrate groups compared to placebo (-34.6 ± 39.1 ng/L on 90 mmol/d, p = 0.05; -71.6 ± 40.7 ng/L on 60 mmol/d, p = 0.02) whereas bone-specific alkaline phosphatase did not change. Intact parathyroid hormone was significantly decreased in the 90 mmol/d group (p = 0.01). Readily available, safe, and easily administered in an oral form, potassium citrate has the potential to improve skeletal health. Longer-term trials with definitive outcomes such as bone density and fracture are needed.
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Kopic S, Geibel JP. Gastric acid, calcium absorption, and their impact on bone health. Physiol Rev 2013; 93:189-268. [PMID: 23303909 DOI: 10.1152/physrev.00015.2012] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Calcium balance is essential for a multitude of physiological processes, ranging from cell signaling to maintenance of bone health. Adequate intestinal absorption of calcium is a major factor for maintaining systemic calcium homeostasis. Recent observations indicate that a reduction of gastric acidity may impair effective calcium uptake through the intestine. This article reviews the physiology of gastric acid secretion, intestinal calcium absorption, and their respective neuroendocrine regulation and explores the physiological basis of a potential link between these individual systems.
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Affiliation(s)
- Sascha Kopic
- Department of Surgery and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut, USA
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O'Brien KO, Donangelo CM, Ritchie LD, Gildengorin G, Abrams S, King JC. Serum 1,25-dihydroxyvitamin D and calcium intake affect rates of bone calcium deposition during pregnancy and the early postpartum period. Am J Clin Nutr 2012; 96:64-72. [PMID: 22648718 PMCID: PMC3374733 DOI: 10.3945/ajcn.111.029231] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Factors affecting bone calcium deposition across pregnancy and lactation are not well characterized. OBJECTIVE The impact of maternal age, calcium intake, race-ethnicity, and vitamin D status on the rate of bone calcium deposition (VO+) was assessed across pregnancy and lactation. DESIGN Stable calcium isotopes were given to 46 women at pre- or early pregnancy (trimester 1), late pregnancy (trimester 3), and 3-10 wk postpartum. Three cohorts were included: 23 adolescents from Baltimore (MD), aged 16.5 ± 1.4 y (mean ± SD; Baltimore cohort); 13 adults from California, aged 29.5 ± 2.6 y (California cohort); and 10 adults from Brazil, aged 30.4 ± 4.0 y (Brazil cohort). The total exchangeable calcium pool, VO+, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D [1,25(OH)₂D], parathyroid hormone, and calcium intake were evaluated. RESULTS At trimester 3, inverse associations between 1,25(OH)₂D and VO+ were evident in the Baltimore (P = 0.059) and Brazil (P = 0.008) cohorts and in the whole group (P = 0.029); calcium intake was not a significant determinant of VO+ in any group during pregnancy. At postpartum, a significant positive association was evident between VO+ and calcium intake (P ≤ 0.002) and between VO+ and African ethnicity (P ≤ 0.004) in the whole group and within the Baltimore and Brazil cohorts. CONCLUSIONS Elevated 1,25(OH)₂D was associated with decreased rates of bone calcium deposition during late pregnancy, a finding that was particularly evident in pregnant adolescents and adult women with low calcium intakes. Higher dietary calcium intakes and African ethnicity were associated with elevated rates of bone calcium deposition in the postpartum period.
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Ueda Y, Taira Z. Pharmacokinetic Characterization of Calcium from Three Calcium Salts (Calcium Chloride, Calcium Acetate and Calcium Ascorbate) in Mice. J HARD TISSUE BIOL 2012. [DOI: 10.2485/jhtb.21.291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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20
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Young MF, Griffin I, Pressman E, McIntyre AW, Cooper E, McNanley T, Harris ZL, Westerman M, O’Brien KO. Maternal hepcidin is associated with placental transfer of iron derived from dietary heme and nonheme sources. J Nutr 2012; 142:33-9. [PMID: 22113871 PMCID: PMC3237230 DOI: 10.3945/jn.111.145961] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The determinants of placental transport of dietary iron remain largely uncharacterized. The objective of this research was to elucidate determinants of fetal Fe transfer from maternally ingested dietary heme and non-heme Fe. The study was undertaken in 19 pregnant females (16-32 y) who ingested intrinsically labeled (58)Fe-heme and a nonheme Fe source ((57)FeSO(4)) during the third trimester of pregnancy. At delivery, maternal and cord blood was obtained to assess neonatal (57)Fe and (58)Fe enrichment as a function of maternal/neonatal Fe status [serum ferritin (SF), transferrin receptor, hemoglobin (Hb), total body Fe, and hepcidin]. There was a greater percentage of maternally absorbed (58)Fe tracer present in the neonates compared to the (57)Fe tracer (5.4 ± 2.4 vs. 4.0 ± 1.6; P < 0.0001). Net dietary nonheme Fe (mg) and heme Fe (mg) transferred to the fetus were both inversely correlated with measures of maternal serum hepcidin (P = 0.002, r(2) = 0.43; P = 0.004, r(2) = 0.39) and SF (P = 0.0008, r(2) = 0.49; P = 0.003, r(2) = 0.41) and directly associated with neonatal Hb (P = 0.004, r(2) = 0.39; P = 0.008, r(2) = 0.35). The results of this study suggest that during pregnancy there appears to be preferential fetal use of maternally ingested Fe derived from a dietary, animal-based heme source compared to Fe ingested as ferrous sulfate. Maternal serum hepcidin and maternal/neonatal Fe status may play a role in placental uptake of dietary heme and nonheme Fe.
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Affiliation(s)
- Melissa F. Young
- Cornell University, Division of Nutritional Sciences, Ithaca, NY
| | - Ian Griffin
- USDA/Agricultural Research Service Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX
| | - Eva Pressman
- The University of Rochester School of Medicine, Rochester, NY
| | | | | | - Thomas McNanley
- The University of Rochester School of Medicine, Rochester, NY
| | - Z. Leah Harris
- Vanderbilt University Medical Center, Department of Pediatrics, Nashville, TN; and
| | | | - Kimberly O. O’Brien
- Cornell University, Division of Nutritional Sciences, Ithaca, NY,To whom correspondence should be addressed. E-mail:
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21
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Shapses SA, Kendler DL, Robson R, Hansen KE, Sherrell RM, Field MP, Woolf E, Berd Y, Mantz AM, Santora AC. Effect of alendronate and vitamin D₃ on fractional calcium absorption in a double-blind, randomized, placebo-controlled trial in postmenopausal osteoporotic women. J Bone Miner Res 2011; 26:1836-44. [PMID: 21448918 DOI: 10.1002/jbmr.395] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Menopause and increasing age are associated with a decrease in calcium absorption that can contribute to the pathogenesis of osteoporosis. We hypothesized that alendronate plus vitamin D(3) (ALN + D) would increase fractional calcium absorption (FCA). In this randomized, double-blind, placebo-controlled multicenter clinical trial, 56 postmenopausal women with 25-hydroxyvitamin D [25(OH)D] concentrations of 25 ng/mL or less and low bone mineral density (BMD) received 5 weekly doses of placebo or alendronate 70 mg plus vitamin D(3) 2800 IU (ALN + D). Calcium intake was stabilized to approximately 1200 mg/d prior to randomization. FCA was determined using a dual-tracer stable-calcium isotope method. FCA and 25(OH)D were similar between treatment groups at baseline (0.31 ± 0.12 ng/mL and 19.8 ± 4.7 ng/mL, respectively). After 1 month of treatment, subjects randomized to ALN + D experienced a significant least squares (LS) mean [95% confidence interval (CI)] increase in FCA [0.070 (0.042, 0.098)], whereas FCA did not change significantly in the placebo group [-0.016 (-0.044, 0.012)]. After ALN + D treatment, patients had higher 25(OH)D levels (LS mean difference 7.3 ng/mL, p < .001). The rise in serum 1,25-dihydroxyvitamin D(3) (p < .02) and parathyroid hormone (p < .001) were greater in the ALN + D group than in placebo-treated patients. ALN + D was associated with an increase in FCA of 0.07. To our knowledge, there is no other trial showing such a marked rise in calcium absorption owing to treatment with a bisphosphonate or owing to a small rise in 25(OH)D. This unique response of ALN + D is important for the treatment of osteoporosis, but the exact mechanism requires further study.
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Affiliation(s)
- Sue A Shapses
- Department of Nutritional Sciences, Rutgers University, New Brunswick, NJ 08901, USA.
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22
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Lee WH, McCabe GP, Martin BR, Weaver CM. Simple isotopic method using oral stable or radioactive tracers for estimating fractional calcium absorption in adult women. Osteoporos Int 2011; 22:1829-34. [PMID: 20936404 DOI: 10.1007/s00198-010-1420-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Accepted: 09/15/2010] [Indexed: 10/19/2022]
Abstract
UNLABELLED We extended a simple oral method for estimating fractional calcium absorption determined by double isotopic methods using radioactive or stable isotope across wide age of adult women. Fractional calcium absorption can be estimated by using either a radioactive or stable oral isotope across the entire age spectrum of adult women. INTRODUCTION A method for estimating fractional calcium absorption using a single serum collection following a single oral radioactive isotopic tracer has been validated against a classical double isotopic tracer ratio method in adults. Our goal was to extend this simplified method to include use of stable isotopes and a broad age range. METHODS We used our database of 56 observations from 26 white adult women aged 19-67 years receiving either radioactive or stable isotopes. Reference values for fractional calcium absorption were determined from 24-h double isotopic ratios in serum and urine and from full kinetic modeling. RESULTS Equations for estimating fractional calcium absorption were developed from isotopic enrichment in serum and urine from an oral tracer and measures of body size using the multiple linear regression analysis. Equations using a 4- to 6-h sample following an oral dose of either a stable or radioactive isotope corrected for body size were highly correlated with the reference values for fractional calcium absorption across different aged populations (r > 0.8, p < 0.001). CONCLUSION Fractional calcium absorption can be estimated by a single oral tracer method using either radioactive or stable calcium isotopes across the entire age spectrum in healthy white adult women.
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Affiliation(s)
- W H Lee
- Agricultural and Biological Engineering, Purdue University, West Lafayette, IN 47907-2059, USA
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23
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Lee W, McCabe GP, Martin BR, Weaver CM. Validation of a simple isotope method for estimating true calcium fractional absorption in adolescents. Osteoporos Int 2011; 22:159-66. [PMID: 20358361 DOI: 10.1007/s00198-010-1203-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Accepted: 01/25/2010] [Indexed: 11/24/2022]
Abstract
UNLABELLED We validated a single oral isotope method for estimating fractional calcium absorption determined by double isotope methods in adolescents. Developed equations with an oral isotope including a single blood draw or spot urine collection can be used to evaluate fractional calcium absorption in adolescents which allows flexibility in developing protocols. INTRODUCTION This study was designed to develop and validate a simpler, less expensive single oral isotope method for determining fractional calcium (Ca) absorption in adolescents. METHODS We used our database of 31 observations from ten white and 12 black adolescent girls aged 10-15 years who participated in metabolic and kinetic studies. Tracer data following oral ((44)Ca) and intravenous (IV, (42)Ca) administration of calcium stable isotopes and samples in serum and urine from various time points up to 4 days were used to develop methods using multiple regression analysis based on a single measurement of enriched stable isotope/tracee defined as tracer/tracee (TT) in serum (TT(serum)) or urine (TT(urine)). Reference values for fractional calcium absorption were from oral/IV stable isotope ratios in 24-h serum or urine and full kinetic modeling. RESULTS The strongest equation using a single blood sample had R (2) = 0.94 (p < 0.001): fractional Ca absorption = 1.3340(4-h TT(serum))(0.7872) BSA(1.7132)e ((-0.01652 PMA)), where BSA is body surface area and PMA is post-menarcheal age. The strongest equation using a single urine sample had R (2) = 0.95 (p < 0.001): fractional Ca absorption = 2.3088 (5-12 h TT(urine))(0.8208) BSA(1.5260)e ((-0.01850 PMA)). Equations were also developed with Tanner score. An external data set of Asian adolescent boys and girls was used to validate the equations. CONCLUSION Equations using an oral isotope and a single blood draw or urine collection for determining fractional calcium absorption were successfully validated in healthy, non-obese white and black adolescent girls aged 10-15 years. The equations well-predicted fractional calcium absorption in Asian adolescent boys and girls.
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Affiliation(s)
- W Lee
- Agricultural and Biological Engineering, Purdue University, West Lafayette, IN 47907-2059, USA
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24
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Kumari M, Khazai NB, Ziegler TR, Nanes MS, Abrams SA, Tangpricha V. Vitamin D-mediated calcium absorption in patients with clinically stable Crohn's disease: a pilot study. Mol Nutr Food Res 2010; 54:1085-91. [PMID: 20306476 DOI: 10.1002/mnfr.200900351] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Vitamin D is the critical hormone for intestinal absorption of calcium. Optimal calcium absorption is important for proper mineralization of bone in the prevention of osteoporosis and osteoporotic fractures, among other important functions. Diseases associated with gut inflammation, such as Crohn's disease (CD), may impair calcium absorption. This pilot study evaluated vitamin D- dependent calcium absorption in subjects with CD. Male subjects with CD (n=4) and healthy age-matched controls (n=5) were studied. All subjects had fractional calcium absorption (FCA; by the dual calcium isotope method), serum 25-hydroxyvitamin D, serum calcium and 24 h urinary calcium excretion measurements at baseline. The FCA in response to vitamin D therapy was re-assessed following administration of oral calcitriol 0.25 mcg twice daily for 1 wk, followed by oral calcitriol 0.50 mcg twice daily for 1 wk. Serum calcium and 24 h urinary calcium determinations were re-assessed after each increasing dose of calcitriol as safety measures. There was no significant difference in calcium FCA at baseline or after increasing doses of calcitriol between the CD and controls. FCA in the control and CD group was approximately 35% at baseline, which increased to 60% after calcitriol therapy. No subject developed hypercalcemia or hypercalciuria. Our results suggest that CD patients have a normal response to vitamin D in enhancing the efficacy of calcium absorption. This suggests that stable CD patients can follow calcium and vitamin D guidelines of non-CD adults. Other factors independent of vitamin D status may impair intestinal calcium absorption in CD, including the degree and location of inflammation, presence of surgical resection and/or use of glucocorticoids.
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Affiliation(s)
- Meena Kumari
- Division of Endocrinology, Metabolism and Lipids, Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
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25
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Thacher TD, Abrams SA. Relationship of calcium absorption with 25(OH)D and calcium intake in children with rickets. Nutr Rev 2010; 68:682-8. [PMID: 20961298 DOI: 10.1111/j.1753-4887.2010.00338.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Nutritional rickets has long been considered a disease caused by vitamin D deficiency, but recent data indicate that inadequate dietary calcium intake is an important cause of rickets, particularly in tropical countries. Children with rickets due to calcium deficiency do not have very low 25(OH)D concentrations, and serum 1,25(OH)(2) D values are markedly elevated. Studies of Nigerian children with rickets demonstrated they have high fractional calcium absorption. A high-phytate diet was demonstrated to increase calcium absorption compared with the fasting state, and enzymatic dephytinization did not significantly improve calcium absorption. When given vitamin D, children with rickets have a marked increase in 1,25(OH)(2) D concentrations without any change in fractional calcium absorption. No positive relationship was found between fractional calcium absorption and serum 25(OH)D concentrations in children on low-calcium diets. More research is needed to understand the interaction between calcium and vitamin D and the role of vitamin D in calcium absorption.
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Affiliation(s)
- Tom D Thacher
- Department of Family Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA.
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26
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Ceglia L, Abrams SA, Harris SS, Rasmussen HM, Dallal GE, Dawson-Hughes B. Evaluation of an inexpensive calcium absorption index in healthy older men and women. Clin Endocrinol (Oxf) 2010; 72:22-5. [PMID: 19320650 PMCID: PMC4431538 DOI: 10.1111/j.1365-2265.2009.03576.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Calcium absorption is an important determinant of calcium retention and bone metabolism. However, most methods of measuring calcium absorption, including the well-established dual stable isotope method, are costly and cumbersome to implement. We evaluated whether an oral calcium tolerance test (OCTT), which involves measuring calcium excretion in a fasting 2-h urine collection and two 2-h collections following an oral calcium dose, may be a useful index of calcium absorption in older adults consuming a fixed calcium intake of 30 mmol/day. DESIGN After a 10-day metabolic diet containing 30 mmol/day of calcium, subjects had calcium absorption measured using the dual stable isotope method and the OCTT. PARTICIPANTS Eleven healthy subjects aged 54-74 years. MEASUREMENTS Fractional calcium absorption (FCA), calcium excretion in a fasting 2-h urine collection and two 2-h collections in response to a 10-mmol calcium dose (total intake 30 mmol/day). RESULTS Calcium excretion from several combinations of the urine collections was examined in relation to FCA. The most predictive of FCA was calcium excretion 4 h following the calcium dose. This measure was significantly correlated with FCA (r = 0.735, P = 0.010), fitting 54% of the variability in FCA. CONCLUSION Urinary calcium excretion during the 4 h after a 10-mmol calcium dose is a useful index of calcium absorption among older adults consuming recommended calcium intakes. This test is inexpensive, easy to implement and potentially useful in large clinical studies.
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Affiliation(s)
- Lisa Ceglia
- Jean Mayer United States Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111, USA.
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Ceglia L, Abrams SA, Harris SS, Rasmussen HM, Dallal GE, Dawson-Hughes B. A simple single serum method to measure fractional calcium absorption using dual stable isotopes. Exp Clin Endocrinol Diabetes 2009; 118:653-6. [PMID: 19856249 DOI: 10.1055/s-0029-1234088] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
The dual stable isotope method with a timed 24-h urine collection is the gold standard approach to measure fractional calcium absorption. However, the need to collect urine for 24 h makes this technique time-consuming and laborious. Our study sought to determine whether a dual isotope method using a single serum sample obtained 4 h after administration of the initial isotope provides a useful approach to measure fractional calcium absorption. Following a metabolic diet with a fixed calcium intake of 30 mmol/day for 10 days, nineteen healthy subjects age 54-74 were given a test meal with an oral isotope ((44)Ca) followed 2 h later by an intravenous isotope ((42)Ca). Once the oral isotope was administered, urine was collected for 24 h, and a serum sample was obtained after 4 h. The ratio of the oral to intravenous isotopes was measured in the urine and serum by mass spectroscopy. Fractional calcium absorption was 16.2 ± 7.7% by the 4-h single serum method versus 18.5 ± 7.5% by the 24-h urine method. There was a small mean difference between the urine and serum methods of 2.33% with a confidence interval -3.97 to 8.60%. The two methods showed a strong linear association (r = 0.912, p<0.001). Use of dual stable isotopes with a 4-h single serum method gives fractional calcium absorption values that are 12.5% lower than with the 24-h urine method; however, it rank orders subjects accurately thus making it a useful alternative method in clinical research applications.
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Affiliation(s)
- L Ceglia
- Jean Mayer United States Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111, USA.
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Ceglia L, Harris SS, Abrams SA, Rasmussen HM, Dallal GE, Dawson-Hughes B. Potassium bicarbonate attenuates the urinary nitrogen excretion that accompanies an increase in dietary protein and may promote calcium absorption. J Clin Endocrinol Metab 2009; 94:645-53. [PMID: 19050051 PMCID: PMC2730228 DOI: 10.1210/jc.2008-1796] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Protein is an essential component of muscle and bone. However, the acidic byproducts of protein metabolism may have a negative impact on the musculoskeletal system, particularly in older individuals with declining renal function. OBJECTIVE We sought to determine whether adding an alkaline salt, potassium bicarbonate (KHCO3), allows protein to have a more favorable net impact on intermediary indices of muscle and bone conservation than it does in the usual acidic environment. DESIGN We conducted a 41-d randomized, placebo-controlled, double-blind study of KHCO3 or placebo with a 16-d phase-in and two successive 10-d metabolic diets containing low (0.5 g/kg) or high (1.5 g/kg) protein in random order with a 5-d washout between diets. SETTING The study was conducted in a metabolic research unit. PARTICIPANTS Nineteen healthy subjects ages 54-82 yr participated. INTERVENTION KHCO3 (up to 90 mmol/d) or placebo was administered for 41 d. MAIN OUTCOME MEASURES We measured 24-h urinary nitrogen excretion, IGF-I, 24-h urinary calcium excretion, and fractional calcium absorption. RESULTS KHCO3 reduced the rise in urinary nitrogen excretion that accompanied an increase in protein intake (P = 0.015) and was associated with higher IGF-I levels on the low-protein diet (P = 0.027) with a similar trend on the high-protein diet (P = 0.050). KHCO3 was also associated with higher fractional calcium absorption on the low-protein diet (P = 0.041) with a similar trend on the high-protein diet (P = 0.064). CONCLUSIONS In older adults, KHCO3 attenuates the protein-induced rise in urinary nitrogen excretion, and this may be mediated by IGF-I. KHCO3 may also promote calcium absorption independent of the dietary protein content.
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Affiliation(s)
- Lisa Ceglia
- Jean Mayer United States Department of Agriculture Human Nutrition Research Center on Aging at Tufts University, 711 Washington Street, Boston, Massachusetts 02111, USA.
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29
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Abrams SA. Assessing mineral metabolism in children using stable isotopes. Pediatr Blood Cancer 2008; 50:438-41; discussion 451. [PMID: 18064657 DOI: 10.1002/pbc.21417] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Mineral metabolism may be altered in children with acute or chronic illnesses. The effects may be short term, such as hypomagnesemia associated with chemotherapy, or long-term, such as loss of bone mineral mass after steroid use. Understanding the causes, consequences, and potential therapies for mineral disorders is enhanced by understanding the absorption, body utilization, and turnover of these minerals. These assessments can now be done safely and readily using non-radioactive, stable isotopes which are available for calcium, zinc, magnesium, and iron. The methods for measurement of mineral absorption and kinetics (turnover) are well established, especially for calcium, and have been tested in every age group. Few studies, however, have been performed in children with acute or chronic illnesses such as cancer. Isotope dosing and infusion protocols are minimally invasive and protocols require small blood or urine volumes. Mineral absorption can be assessed without collecting fecal samples. Kinetics are assessed with blood and urine collections, usually over 5-10 days. Increased use of these techniques may be important in medical and nutritional assessment as well as in the management of pediatric oncology patients.
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Affiliation(s)
- Steven A Abrams
- US Department of Agriculture/Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine and Texas Children's Hospital, Houston, Texas, USA.
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Dickerson RN, Morgan LM, Croce MA, Minard G, Brown RO. Treatment of moderate to severe acute hypocalcemia in critically ill trauma patients. JPEN J Parenter Enteral Nutr 2007; 31:228-33. [PMID: 17463149 DOI: 10.1177/0148607107031003228] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Our recent data indicate that 21% of critically ill, adult, multiple-trauma patients receiving specialized nutrition support experience hypocalcemia. However, evidence-based methods for the treatment of moderate to severe acute hypocalcemia (ionized calcium concentration [iCa] <1 mmol/L) are lacking. METHODS The efficacy of an infusion of 4 g of calcium gluconate was evaluated in 20 critically ill, adult, multiple-trauma patients with moderate to severe hypocalcemia (iCa <1 mmol/L). The calcium gluconate was infused at a rate of 1 g/h in a small volume admixture. A serum iCa determination was obtained on the following day. RESULTS Calcium gluconate infusion significantly increased serum iCa from 0.90 +/- 0.08 mmol/L to 1.16 +/- 0.11 mmol/L (p < .001) on the following day. This dosage regimen was successful for achieving a serum iCa >1 mmol/L for 19 of 20 (95%) hypocalcemic patients and achieved a concentration >1.12 mmol/L in 14 (70%) of the patients. Two patients developed mild hypercalcemia (iCa of 1.34 mmol/L and 1.38 mmol/L) postinfusion. CONCLUSIONS A short-term infusion of 4 g of intravenous (IV) calcium gluconate for the treatment of moderate to severe hypocalcemia appears to be a promising regimen for critically ill, adult, multiple-trauma patients.
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Affiliation(s)
- Roland N Dickerson
- Department of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA.
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Dainty JR, Bullock NR, Hart DJ, Hewson AT, Turner R, Finglas PM, Powers HJ. Quantification of the bioavailability of riboflavin from foods by use of stable-isotope labels and kinetic modeling. Am J Clin Nutr 2007; 85:1557-64. [PMID: 17556693 DOI: 10.1093/ajcn/85.6.1557] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Discrepancies have been reported between estimates of the prevalence of riboflavin deficiency based on intakes of riboflavin and estimates based on measures of riboflavin status. One reason for this may be an overestimate of the bioavailability of riboflavin from foods, about which relatively little is known. OBJECTIVE We aimed to quantify the bioavailability of riboflavin from milk and spinach by using stable-isotope labels and a urinary monitoring technique and by a plasma appearance method based on kinetic modeling. DESIGN Twenty healthy women aged 18-65 y were recruited for a randomized crossover study performed with extrinsically labeled (13C) milk and intrinsically labeled (15N) spinach as sources of riboflavin. An intravenous bolus of labeled riboflavin was administered with each test meal to assess the apparent volume of distribution of riboflavin in plasma. RESULTS No significant differences were noted in riboflavin absorption from the spinach meal and from the milk meal according to either the urinary monitoring technique (60 +/- 8.0% and 67 +/- 5.4%, respectively; P = 0.549) or the plasma appearance method (20 +/- 2.8% and 23 +/- 5.3%, respectively; P = 0.670). CONCLUSIONS A large fraction of newly absorbed riboflavin is removed by the liver on "first pass." The plasma appearance method therefore underestimates riboflavin bioavailability and should not be used to estimate riboflavin bioavailability from foodstuffs. Urinary monitoring suggests that riboflavin from spinach is as bioavailable as is riboflavin from milk.
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Kim J, Paik HY, Joung H, Woodhouse LR, Li S, King JC. Effect of dietary phytate on zinc homeostasis in young and elderly Korean women. J Am Coll Nutr 2007; 26:1-9. [PMID: 17353577 DOI: 10.1080/07315724.2007.10719579] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
BACKGROUND Previous studies suggest that consumption of predominantly plant-based diets with high phytate content contribute to zinc deficiency by inhibiting zinc absorption. Age of the individual may also affect the ability to maintain zinc homeostasis. OBJECTIVE This study was designed to determine the effect of dietary phytate on zinc homeostasis and to evaluate the effect of age on the capacity to maintain the zinc homeostasis with changes in dietary phytate in young and elderly Korean women. DESIGN AND METHODS Seven healthy young women (22-24 yr) and 10 healthy elderly women (66-75 yr) were studied consecutively for 3 months in 2 metabolic periods (MP) in two different metabolic units. During MP1 the women consumed a high phytate (HP) diet (P:Zn molar ratio = 23) for 9 days. After a 10 d wash-out period at home eating their usual diets, a lower phytate diet (LP) (P:Zn molar ratio = 10) was fed in MP2 for 9 d. Phytase was added to selected foods in the high phytate diet to reduce the phytate content of the meals in the LP period. The zinc content of both diets was about 6.5 mg/d. Stable isotopes of Zn ((70)Zn) were administered intravenously on d 5 of MP 1 and 2 for measuring endogenous fecal zinc excretion. Plasma samples were also collected on d 5 for measuring plasma zinc concentrations by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). 24 hr urine samples were collected for 5 d and complete fecal samples were collected for 9 d after isotope administration. Fractional zinc absorption (FZA) was calculated from mass balance corrected for endogenous fecal zinc (EFZ) excretion and EFZ was determined by using an isotopic dilution technique. Isotopic ratios for FZA and EFZ were measured by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Statistical analyses were done using ANOVA. RESULTS Both the young and elderly women were in negative zinc balance during the HP period. This was due to a significant decrease in FZA and total absorbed zinc (TAZ) with a HP diet (43 vs 22% in young women, 34 vs 20% in elderly women, p < 0.001). EFZ excretion did not differ in the young and elderly women during the LP and HP periods. Dietary phytate did not alter plasma zinc concentrations or and urinary zinc excretion in either group. CONCLUSIONS Adjustments in zinc homeostasis with an increase in dietary phytate did not differ between young and elderly women in this study.
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Affiliation(s)
- Jihye Kim
- Children's Hospital Oakland Research Institute, 5700 Martin Luther King Jr. Way, Oakland, CA 94609, USA
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Griffin IJ, Davila PM, Abrams SA. Non-digestible oligosaccharides and calcium absorption in girls with adequate calcium intakes. Br J Nutr 2007. [DOI: 10.1079/bjn/2002536] [Citation(s) in RCA: 165] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Non-digestible oligosaccharides such as inulin and oligofructose have been shown to consistently increase calcium absorption in experimental animals, but data in humans are less clear-cut. The objective of this study was to assess the effect of 8 g/d of oligofructose or a mixture of inulin and oligofructose on calcium absorption in girls at or near menarche. A total of fifty-nine subjects were studied using a balanced, randomized, cross-over design. They received, in random order, 8 g/d placebo (sucrose), oligofructose or the mixture inulin+oligofructose for 3 weeks, separated by a 2-week washout period. Throughout the study, subjects consumed a total of approximately 1500 mg/d dietary calcium, by adding two glasses of calcium-fortified orange juice to their diet. Four grams of placebo, oligofructose or the mixture inulin+oligofructose was added to each glass of orange juice immediately before it was consumed. At the end of each 3-week adaptation period, calcium absorption was measured, using a dual stable isotope technique, from the cumulative fractional excretion of an oral and an intravenous tracer over 48 hours. Calcium absorption was significantly higher in the group receiving the inulin+oligofructose mixture than in the placebo group (38·2±9·8 % v. 32·3±9·8 %; P=0·01), but no significant difference was seen between the oligofructose group and the placebo group (31·8±9·3 % v. 31·8±10·0 %, P=NS). We conclude that modest intakes of an inulin+oligofructose mixture increases calcium absorption in girls at or near menarche.
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Heller HJ, Zerwekh JE, Gottschalk FA, Pak CYC. Reduced bone formation and relatively increased bone resorption in absorptive hypercalciuria. Kidney Int 2007; 71:808-15. [PMID: 17311067 DOI: 10.1038/sj.ki.5002181] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Absorptive hypercalciuria (AH), a common stone-forming condition characterized biochemically by intestinal hyperabsorption of calcium and hypercalciuria may be associated with bone loss. In AH type I (AH-1), hypercalciuria persists despite restriction in dietary calcium intake. We therefore hypothesized that the skeleton may contribute to the hypercalciuria in this subgroup of patients. Histomorphometric analysis of iliac crest biopsies were performed on nine stone-formers with AH-1 and on nine matched normal subjects. After stabilization on a stone-prevention diet, calcium homeostasis in the stone formers was then evaluated on inpatient constant metabolic diet before and after short-term blockade of bone resorption by alendronate (10 mg daily, 17 days total). Compared with controls, the stone-formers had lower indices of bone formation (osteoblast surface/bone surface 1.8+/-2.1 vs 3.0+/-1.5%, P=0.04; wall thickness 35.8+/-6.9 vs 47.2+/-7.6%, P=0.001) and relatively higher bone resorption (osteoclast surface/bone surface 0.4+/-0.2 vs 0.2+/-0.2%, P=0.05). In the stone-formers, a short-term course of alendronate treatment corrected fasting urinary calcium (0.14+/-0.06 to 0.06+/-0.04 mg Ca/mg Cr, P=0.001) and marginally reduced 24-h urinary calcium by 48 mg/day (P=0.06). Increased intestinal calcium absorption and hypercalciuria persisted, but estimated calcium balance improved (P=0.007). Our results suggest that the hypercalciuria of AH-1 originates primarily from intestinal hyperabsorption of calcium, but bone resorption in excess of bone formation may contribute.
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Affiliation(s)
- H J Heller
- Department of Internal Medicine, UT Southwestern Medical Center at Dallas, Center for Mineral Metabolism and Clinical Research, Dallas, Texas, USA
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Bongers A, van den Heuvel EGHM. Prebiotics and the Bioavailability of Minerals and Trace Elements. FOOD REVIEWS INTERNATIONAL 2007. [DOI: 10.1081/fri-120025482] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Anke Bongers
- a Friesland Coberco Dairy Foods , Corporate Research , P.O. Box 87, 7400 AB , Deventer , The Netherlands
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36
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Dickerson RN, Morgan LM, Croce MA, Minard G, Brown RO. Dose-dependent characteristics of intravenous calcium therapy for hypocalcemic critically ill trauma patients receiving specialized nutritional support. Nutrition 2006; 23:9-15. [PMID: 17123782 DOI: 10.1016/j.nut.2006.10.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2006] [Revised: 09/27/2006] [Accepted: 10/01/2006] [Indexed: 11/24/2022]
Abstract
OBJECTIVE The purpose of this investigation was to evaluate the dose-dependent characteristics of intravenous calcium gluconate therapy for hypocalcemic critically ill patients. METHODS The dose-dependent characteristics of 2 g versus 4 g of intravenous calcium gluconate therapy were evaluated in 25 critically ill, adult multiple trauma patients with hypocalcemia. The calcium gluconate was infused at a rate of 1 g/h for both groups. Patients weighed within 90% to 120% of ideal body weight, had normal renal function, did not receive diuretic therapy, and did not have anasarca. RESULTS Fifteen patients with mild hypocalcemia (serum ionized calcium concentration [iCa] 1-1.12 mmol/L) were given 2 g of calcium gluconate. Ten patients with moderate to severe hypocalcemia (iCa <1 mmol/L) were given 4 g. Each dosage group had a significant (P < or = 0.001) increase in iCa (from 1.07 +/- 0.05 to 1.17 +/- 0.05 mmol/L and from 0.92 +/- 0.08 to 1.16 +/- 0.11 mmol/L, respectively). Each dosage group retained about half of the dose in the exchangeable calcium space (P = NS between groups), but the higher dosage group retained significantly more elemental calcium overall (81 +/- 38 versus 201 +/- 50 mg, respectively, P < or = 001). Serum ionized calcium concentrations achieved a plateau without a further decline in iCa by 10 h after completion of the infusion for each dosage. CONCLUSION About half of the administered elemental calcium dose was retained for each dosage group, with the higher dose (4 g) resulting in significantly more elemental calcium retention in the exchangeable calcium space. An iCa determination performed about > or =10 h after the completion of the calcium gluconate infusion should be sufficient time to ensure equilibration of iCa to assess the efficacy of the therapy. This mode of calcium therapy serves as an effective means for providing calcium to the acutely hypocalcemic, critically ill, multiple trauma patient.
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Affiliation(s)
- Roland N Dickerson
- Department of Clinical Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee, USA.
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Dickerson RN, Morgan LG, Cauthen AD, Alexander KH, Croce MA, Minard G, Brown RO. Treatment of acute hypocalcemia in critically ill multiple-trauma patients. JPEN J Parenter Enteral Nutr 2006; 29:436-41. [PMID: 16224037 DOI: 10.1177/0148607105029006436] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Recent data indicate that critically ill, adult multiple trauma patients receiving specialized nutrition support commonly experience hypocalcemia (ionized serum calcium [iCa] < or =1.12 mmol/L). However, validated methods for the treatment of acute hypocalcemia are lacking. METHODS The efficacy of a single dose of calcium gluconate using an empiric IV calcium gluconate graduated dosing regimen was evaluated in 37 patients. Patients with an iCa of 1-1.12 mmol/L (mild hypocalcemia) were provided 1-2 g of IV calcium gluconate. Patients with an iCa of <1 mmol/L (moderate to severe hypocalcemia) were given 2-4 g. The calcium gluconate was infused at a rate of 1 g/h in a small-volume admixture. Serum iCa determination was repeated on the following day. RESULTS One to 2 g of IV calcium gluconate was effective in normalizing iCa for 23 out of 29 patients (79%) with mild hypocalcemia and 2-4 g was effective for 3 of 8 patients (38%) with moderate to severe hypocalcemia. The individual response to calcium therapy (g/d) or when normalized to body weight (mg/kg/d) was highly variable. CONCLUSIONS One to 2 g of IV calcium gluconate were effective for most patients with mild hypocalcemia; however, treatment of moderate to severe hypocalcemia with 2-4 g of IV calcium gluconate was often unsuccessful. Further study with frequent serial ionized serum calcium and phosphorus determinations and electrocardiographic monitoring appears to be indicated for patients with moderate to severe hypocalcemia.
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Affiliation(s)
- Roland N Dickerson
- Departments of Pharmacy and Surgery, University of Tennessee Health Science Center, Memphis, 38163, USA.
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O'Brien KO, Donangelo CM, Zapata CLV, Abrams SA, Spencer EM, King JC. Bone calcium turnover during pregnancy and lactation in women with low calcium diets is associated with calcium intake and circulating insulin-like growth factor 1 concentrations. Am J Clin Nutr 2006; 83:317-23. [PMID: 16469990 DOI: 10.1093/ajcn/83.2.317] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Few data exist on longitudinal changes in bone calcium turnover rates across pregnancy and lactation. OBJECTIVE Our aim was to characterize calcium kinetic variables and predictors of these changes across pregnancy and early lactation in women with low calcium intakes. DESIGN Stable calcium isotopes were administered to 10 Brazilian women during early pregnancy (EP; weeks 10-12 of gestation), late pregnancy (LP; weeks 34-36 of gestation), and early lactation (EL; 7-8 wk postpartum). Multicompartmental modeling was used to assess the rates of bone calcium turnover in relation to calcium intakes and circulating concentrations of parathyroid hormone (PTH), insulin-like growth factor 1, and 1,25-dihydroxyvitamin D. RESULTS Rates of bone calcium deposition increased significantly from EP to LP (P = 0.001) and were significantly associated with serum PTH during LP (P < or = 0.01). Rates of bone calcium resorption were also higher during LP and EL than during EP (P < or = 0.01) and were associated with both PTH (P < or = 0.01) and IGF-1 (P < or = 0.05) during LP but not during EL. Net balance in bone calcium turnover was positively associated with dietary calcium during EP (P < or = 0.01), LP (P < or = 0.01), and EL (P < or = 0.01). The mean (+/-SD) calcium intake was 463 +/- 182 mg/d and, in combination with insulin-like growth factor 1, explained 68-94% of the variability in net bone calcium balance during pregnancy and lactation. CONCLUSIONS Net deficits in bone calcium balance occurred during pregnancy and lactation. Increased dietary calcium intake was associated with improved calcium balance; therefore, greater calcium intakes may minimize bone loss across pregnancy and lactation in women with habitual intakes of <500 mg calcium/d.
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Affiliation(s)
- Kimberly O O'Brien
- Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA
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Zhao Y, Martin BR, Weaver CM. Calcium bioavailability of calcium carbonate fortified soymilk is equivalent to cow's milk in young women. J Nutr 2005; 135:2379-82. [PMID: 16177199 DOI: 10.1093/jn/135.10.2379] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Calcium (Ca)-fortified soymilk has gained popularity in the United States. Tricalcium phosphate (TCP)-fortified soymilk was shown to have a lower Ca bioavailability than cow's milk in men. However, the most popular soymilk in the U.S. is fortified with Ca carbonate (CC) and has not been evaluated. Ca bioavailability from CC-fortified soymilk (CCSM) and TCP-fortified soymilk (TCPSM) was compared with cow's milk in young healthy women using the dual stable isotope technique. In a 3-way crossover design, 20 volunteers (23 +/- 2 y old) consumed 250 mg Ca in cow's milk, CCSM, or TCPSM along with 10 mg 44Ca after an overnight fast. Cow's milk was extrinsically labeled, whereas each fortified soymilk was intrinsically labeled with each chemical salt of 44Ca at the manufacturing facility. Another stable isotope, 43Ca, was injected i.v. 1 h after the complete consumption of cow's milk or soymilk. Fractional Ca absorption was determined from the ratios of 43Ca:42Ca and 44Ca:42Ca by inductively coupled plasma (ICP)-MS in the 24-h urine samples. A mixed linear model (SAS proc mixed) was used to compare the fractional Ca absorption among groups. Fractional Ca absorption in CCSM (0.211 +/- 0.057) did not differ from that of cow's milk (0.217 +/- 0.040), but both were higher (P < 0.05) than that of TCPSM (0.181 +/- 0.039). Our result suggests that calcium absorption is equivalent for CCSM and cow's milk at similar calcium loads.
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Affiliation(s)
- Yongdong Zhao
- Department of Foods and Nutrition, Purdue University, West Lafayette, IN, USA
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40
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Griffin IJ, Abrams SA. Methodological considerations in measuring human calcium absorption: relevance to study the effects of inulin-type fructans. Br J Nutr 2005; 93 Suppl 1:S105-10. [PMID: 15877883 DOI: 10.1079/bjn20041344] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
During the last 50 years, a variety of methods have been developed to estimate Ca absorption in man. Mass balances were initially used, but these were unable to accurately measure fractional Ca absorption because they cannot distinguish unabsorbed dietary Ca from endogenous faecal Ca excretion (excretion of previously absorbed Ca back into the gut). A number of isotopic methods have been developed that can measure true fractional Ca absorption, employing radioisotopes, stable isotopes, or both. Different methods involve collection of urine, faecal or plasma samples. Of the currently available methods, the dual isotope tracer method with a timed urine collection is probably the most precise and reliable. It is also relatively straightforward to carry out and avoids the need for a faecal collection. The purpose of the present paper is to discuss the general advantages and disadvantages of the different methods of Ca absorption. In addition, the limitations the different methods have in examining the possible effects of non-digestible oligosaccharides on Ca absorption will be discussed.
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Affiliation(s)
- Ian J Griffin
- USDA/ARS Children's Nutrition Research Center, and Section of Neonatology, Department of Pediatrics, Baylor College of Medicine, 1100 Bates Street, Houston, TX 77030, USA.
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Hambidge KM, Krebs NF, Westcott JL, Sian L, Miller LV, Peterson KL, Raboy V. Absorption of calcium from tortilla meals prepared from low-phytate maize. Am J Clin Nutr 2005; 82:84-7. [PMID: 16002804 PMCID: PMC1592687 DOI: 10.1093/ajcn.82.1.84] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Calcium fortification of maize has been achieved for millennia in Central America by the process of nixtamalization. Bioavailability of calcium is, however, compromised by phytate, which is present in large quantities in maize kernels and is only modestly reduced by nixtamalization. OBJECTIVE The objective was to compare the absorption of calcium from tortilla meals prepared from low-phytate maize with that from meals prepared from maize with typical phytate content. DESIGN At 1-mo intervals, 5 healthy adult women were fed 2 test meals of approximately 140 g tortillas in lieu of breakfast. On one occasion, the tortillas were prepared from maize with approximately 60% phytate reduction, and, on the other occasion, they were prepared from the matching isohybrid wild-type maize. Beginning midway through the test meal, (44)Ca (0.3 mg/kg body wt) was administered in water as an extrinsic label; (42)Ca (0.06 mg/kg body wt) was administered intravenously immediately after the test meal. Isotope ratios of (42)Ca to (43)Ca and of (44)Ca to (43)Ca were measured by inductively coupled plasma mass spectrometry in urine collected as an 8-h pool from the period 16-24 h after intravenous tracer administration and prepared by the oxalate precipitation method. Fractional absorption of calcium was determined by using a dual-isotope ratio technique. RESULTS Mean fractional absorption of calcium from tortillas prepared from the low-phytate maize (0.50 +/- 0.03) was significantly (P = 0.003) greater than that from tortillas prepared from the control maize (0.35 +/- 0.07). CONCLUSION The increase in the quantity of calcium absorbed could be of practical importance for calcium nutriture when the intake of dairy products is limited.
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Affiliation(s)
- K Michael Hambidge
- Department of Pediatrics, Section of Nutrition, University of Colorado Health Sciences Center, Denver, CO 80262, USA.
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Hambidge KM, Krebs NF, Westcott JL, Sian L, Miller LV, Peterson KL, Raboy V. Absorption of calcium from tortilla meals prepared from low-phytate maize. Am J Clin Nutr 2005. [DOI: 10.1093/ajcn/82.1.84] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- K Michael Hambidge
- From the Department of Pediatrics, Section of Nutrition, University of Colorado Health Sciences Center, Denver, CO (KMH, NFK, JLW, LS, and LVM), and the US Department of Agriculture/Agricultural Research Service, Small Grains and Potato Germplasm Research Unit, Aberdeen, ID (KLP and VR)
| | - Nancy F Krebs
- From the Department of Pediatrics, Section of Nutrition, University of Colorado Health Sciences Center, Denver, CO (KMH, NFK, JLW, LS, and LVM), and the US Department of Agriculture/Agricultural Research Service, Small Grains and Potato Germplasm Research Unit, Aberdeen, ID (KLP and VR)
| | - Jamie L Westcott
- From the Department of Pediatrics, Section of Nutrition, University of Colorado Health Sciences Center, Denver, CO (KMH, NFK, JLW, LS, and LVM), and the US Department of Agriculture/Agricultural Research Service, Small Grains and Potato Germplasm Research Unit, Aberdeen, ID (KLP and VR)
| | - Lei Sian
- From the Department of Pediatrics, Section of Nutrition, University of Colorado Health Sciences Center, Denver, CO (KMH, NFK, JLW, LS, and LVM), and the US Department of Agriculture/Agricultural Research Service, Small Grains and Potato Germplasm Research Unit, Aberdeen, ID (KLP and VR)
| | - Leland V Miller
- From the Department of Pediatrics, Section of Nutrition, University of Colorado Health Sciences Center, Denver, CO (KMH, NFK, JLW, LS, and LVM), and the US Department of Agriculture/Agricultural Research Service, Small Grains and Potato Germplasm Research Unit, Aberdeen, ID (KLP and VR)
| | - Kevin L Peterson
- From the Department of Pediatrics, Section of Nutrition, University of Colorado Health Sciences Center, Denver, CO (KMH, NFK, JLW, LS, and LVM), and the US Department of Agriculture/Agricultural Research Service, Small Grains and Potato Germplasm Research Unit, Aberdeen, ID (KLP and VR)
| | - Victor Raboy
- From the Department of Pediatrics, Section of Nutrition, University of Colorado Health Sciences Center, Denver, CO (KMH, NFK, JLW, LS, and LVM), and the US Department of Agriculture/Agricultural Research Service, Small Grains and Potato Germplasm Research Unit, Aberdeen, ID (KLP and VR)
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Vargas Zapata CL, Donangelo CM, Woodhouse LR, Abrams SA, Spencer EM, King JC. Calcium homeostasis during pregnancy and lactation in Brazilian women with low calcium intakes: a longitudinal study. Am J Clin Nutr 2004; 80:417-22. [PMID: 15277164 DOI: 10.1093/ajcn/80.2.417] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Physiologic adjustments in calcium homeostasis during pregnancy and lactation in women with marginal calcium intakes have not been described. OBJECTIVE The objective was to examine longitudinal changes in various aspects of calcium homeostasis during pregnancy and lactation in 9 healthy Brazilian women who habitually consumed approximately 500 mg Ca/d. DESIGN Calcium homeostasis was assessed at 3 time points: 10-12 (early pregnancy, EP) and 34-36 (late pregnancy, LP) wk of pregnancy and 7-8 wk postpartum (early lactation, EL). At each time point, the following variables were measured: dietary calcium intake with a 3-d weighed food record, 24-h urinary calcium excretion (UCa), intestinal calcium absorption (%CaAbs) via administration of stable calcium isotopes with a breakfast meal, serum 1,25-dihydroxyvitamin D, parathyroid hormone (PTH), insulin-like growth factor I (IGF-I), and biochemical markers of bone turnover. RESULTS Dietary calcium did not change during the study. %CaAbs increased from 69.7 +/- 5.4% ( +/- SEM) during EP to 87.6 +/- 4.5% during LP (P < 0.05) and returned to 65.1 +/- 6.2% during EL. Compared with EP, UCa decreased 22% during LP and 68% during EL (P < 0.05). The net mean change in calcium retention was 212 mg/d during LP and 182 mg/d during EL. Several significant associations were found between the main outcome variables (%CaAbs, UCa, and markers of bone turnover) and serum hormones, especially IGF-I and PTH. CONCLUSIONS Calcium homeostasis appears to be attained by a more efficient intestinal calcium absorption during pregnancy and by renal calcium conservation during both pregnancy and lactation. IGF-I and PTH seem to play major roles in the adjustment of calcium metabolism during pregnancy and lactation.
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Cifuentes M, Riedt CS, Brolin RE, Field MP, Sherrell RM, Shapses SA. Weight loss and calcium intake influence calcium absorption in overweight postmenopausal women. Am J Clin Nutr 2004; 80:123-30. [PMID: 15213038 PMCID: PMC4016237 DOI: 10.1093/ajcn/80.1.123] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Weight loss (WL) reduces bone mass and increases fracture risk. Mechanisms regulating calcium metabolism during WL are unclear. OBJECTIVE The objective was to assess the effect of 6 wk of WL at 2 different amounts of calcium intake [normal (NlCa): 1 g/d; high (HiCa): 1.8 g/d] on true fractional calcium absorption (TFCA), bone turnover, and bone-regulating hormones in overweight postmenopausal women. DESIGN Seventy-three women (body mass index, 26.9 +/- 1.9 kg/m(2)) were recruited either to consume a moderately energy-restricted diet (WL group) or to maintain their body weight [weight-maintenance (WM) group] and were randomly assigned to either the HiCa or the NlCa group in a double-blind manner. Subjects underwent weekly diet counseling, and measurements were taken at baseline and after 6 wk. RESULTS Fifty-seven women completed the study and had a baseline TFCA of 24.9 +/- 7.4%. Energy restriction significantly decreased the total calcium absorbed (P < 0.05) in the WL group (n = 32) compared with the WM group (n = 25; analysis of covariance). Regression analysis showed that a greater rate of weight loss suppressed TFCA and the total calcium absorbed (P < 0.05) in the HiCa group. The women in the NlCa WL group absorbed inadequate amounts of calcium (195 +/- 49 mg/d), whereas the women in the HiCa WL group absorbed adequate amounts (348 +/- 118 mg/d). Parathyroid hormone explained 22% of the variance in calcium absorbed in the NlCa group only. CONCLUSIONS We suggest that WL is associated with elevated calcium requirements that, if not met, could activate the calcium-parathyroid hormone axis to absorb more calcium. Normal intakes of calcium during energy restriction result in inadequate total calcium absorption and could ultimately compromise calcium balance and bone mass.
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Affiliation(s)
- Mariana Cifuentes
- Department of Nutritional Sciences, Rutgers University, New Brunswick, NJ 08901, USA
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O'Brien KO, Nathanson MS, Mancini J, Witter FR. Calcium absorption is significantly higher in adolescents during pregnancy than in the early postpartum period. Am J Clin Nutr 2004; 78:1188-93. [PMID: 14668282 DOI: 10.1093/ajcn/78.6.1188] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Early childbearing may limit skeletal consolidation and increase calcium demands in adolescents. OBJECTIVE The purpose of this study was to characterize calcium absorption in pregnant and lactating adolescents. DESIGN Fractional calcium absorption was evaluated in 23 adolescents (mean +/- SD age: 16.5 +/- 1.4 y) during the third trimester of pregnancy (34.7 +/- 1.0 wk gestation) and again in 15 of these adolescents 31 +/- 8 d after delivery. Eight adolescents were breastfeeding their infants during the follow-up study. Fractional calcium absorption was determined by using oral ((46)Ca or (44)Ca) and intravenous ((42)Ca) stable calcium isotopes. Total-body and lumbar spine bone mineral density were measured in adolescents during the postpartum period by using dual-energy X-ray absorptiometry. RESULTS Fractional calcium absorption was significantly greater during pregnancy than at 3-4 wk postpartum [0.526 +/- 0.152 (n = 23) compared with 0.297 +/- 0.108 (n = 15); P < 0.0001]. Lumbar spine z scores measured 19-44 d after delivery (n = 15) were significantly associated with calcium intake during pregnancy (y = -3.53 + 0.107x; R(2) = 0.355, P < 0.02) and were inversely related to fractional calcium absorption during pregnancy (y = 3.489 - 6.66x; R(2) = 0.52, P = 0.002). A total of 33% (5/15) of adolescents had lumbar spine z scores that met the definition of osteopenia (n = 3) or osteoporosis (n = 2) in the early postpartum period. CONCLUSIONS Calcium absorption in adolescents was significantly higher during the third trimester of pregnancy than in the early postpartum period, and higher calcium intakes during pregnancy appeared to be protective against loss of trabecular bone at the lumbar spine.
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Affiliation(s)
- Kimberly O O'Brien
- Center for Human Nutrition, The Johns Hopkins University Bloomberg School of Public Health, 615 North Wolfe Street, Room 2041, Baltimore, MD 21205-2179, USA.
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Chen Z, Griffin IJ, Kriseman YL, Liang LK, Abrams SA. Inductively Coupled Plasma Mass Spectrometric Analysis of Calcium Isotopes in Human Serum: A Low-Sample-Volume Acid-Equilibration Method. Clin Chem 2003; 49:2050-5. [PMID: 14633877 DOI: 10.1373/clinchem.2003.025692] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Abstract
Background: Analytical methods for measuring the calcium isotope distribution in enriched human serum samples that use low blood volumes, simple preparation methods, and rapid analysis are important in clinical studies of calcium kinetics. Previously, sample preparation by oxalate precipitation typically required 500 μL of serum. This method was time-consuming, and the blood volume required was limiting in circumstances when only a small amount of serum could be obtained.
Methods: Serum was collected from humans who were administered 42Ca, and 20 μL of serum was mixed with 2 mL of 0.22–0.67 mol/L HNO3 at room temperature for between 1 min and 16 h. The 42Ca/43Ca ratio in the supernatant was measured by a magnetic sector inductively coupled plasma mass spectrometer (ICP-MS). Calcium isotope ratios from these equilibration solutions were compared with data from oxalate-precipitated serum samples to determine the optimum equilibrium time and the effect of acid concentration on equilibrium.
Results: Various amounts of aggregated particles developed in different acid-serum mixtures. These affected the time required for isotope equilibration in the mixture. The shortest equilibrium time needed for the calcium isotopes varied from 1 to 6 h for samples acidified with 0.22–0.45 mol/L HNO3. Data obtained from these solutions were consistent with data from oxalate-precipitated calcium. The precision of 42Ca/43Ca ratio measurements was better than 0.5%.
Conclusions: We have developed a simple, rapid sample preparation technique for ICP-MS analysis in which 20 μL of serum can be used for accurate measurement of the calcium isotope distribution in a sample with good precision and a rapid analysis time.
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Affiliation(s)
- Zhensheng Chen
- US Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Houston, TX 77030, USA.
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Griffin IJ, Hicks PM, Heaney RP, Abrams SA. Enriched chicory inulin increases calcium absorption mainly in girls with lower calcium absorption. Nutr Res 2003. [DOI: 10.1016/s0271-5317(03)00085-x] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Sabatier M, Keyes WR, Pont F, Arnaud MJ, Turnlund JR. Comparison of stable-isotope-tracer methods for the determination of magnesium absorption in humans. Am J Clin Nutr 2003; 77:1206-12. [PMID: 12716673 DOI: 10.1093/ajcn/77.5.1206] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND The double-labeling (DL) method for determining magnesium absorption is less cumbersome than is the fecal monitoring method, which has been used most often, but it has not been validated. OBJECTIVE The aim of this study was to compare methods and several sampling protocols for determining magnesium absorption to establish a simple and reliable alternative to the fecal monitoring approach. Fecal monitoring was used as the standard against which the DL methods based on urine data (DLU), plasma data (DLP), and plasma kinetics with the use of a deconvolution analysis (DP) were compared. DESIGN Six healthy adult men received 70 mg (26)Mg orally and 30 mg (25)Mg intravenously. Multiple blood samples and complete urine and fecal samples were collected over 12 d. Stable-isotope ratios were determined by inductively coupled plasma mass spectrometry. RESULTS Results from DLU were not significantly different from the fecal monitoring reference value (0.48 +/- 0.05; +/- SD) when based on 3-d urine pools from 72 to 144 h (0.54 +/- 0.04) and when based on the 24-h urine pools from 48 to 72 h (0.49 +/- 0.06), 72 to 96 h (0.51 +/- 0.11), and 96 to 120 h (0.50 +/- 0.06). Results with the DLP method 72 h after isotope administration also compared well with those with the fecal monitoring method (0.54 +/- 0.09). Magnesium absorption was 0.47 +/- 0.06 with the DP method, which also agreed with the fecal monitoring value. CONCLUSIONS The DL methods are an alternative to fecal monitoring when applied within the appropriate time intervals. Therefore, DLU-the simplest and least invasive approach-is recommended for determining magnesium absorption.
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Abstract
Calcium absorption was measured simultaneously by tracer and pharmacokinetic methods in 12 men. The purpose of the study was to calibrate the area under the curve (AUC) for absorptive calcemia to permit comparison or pooling of pharmacokinetic data with tracer-derived estimates. Each subject was studied twice during intake of 500 mg calcium loads (as the carbonate salt), once without excipients, and once with a binder that impeded dissolution of the salt, reducing its absorbability and thereby providing a broad range of absorption values over which to calibrate the method. Various time periods were evaluated, with the best prediction being given by the AUC for the increment in serum calcium calculated over 9 h (AUC(9)). For net absorbed calcium (mmol) the relationship was given by 4.358 x AUC(9) +/- 0.820. The empirical regression coefficient was significant and the error of the estimate (0.820 mmol) acceptably small.
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Affiliation(s)
- Robert P Heaney
- Osteoporosis Research Center, Creighton University, Omaha, NE, USA.
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Roughead ZK. Is the interaction between dietary protein and calcium destructive or constructive for bone? J Nutr 2003; 133:866S-869S. [PMID: 12612171 DOI: 10.1093/jn/133.3.866s] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Zamzam K Roughead
- Agricultural Research Service, Grand Forks Human Nutrition Research Center, U.S. Department of Agriculture, Grand Forks, ND 58202-9034, USA.
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