28 results on '"Walczyk, Thomas"'
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2. 41Ca measurements on the 1 MV AMS facility at the Centro Nacional de Aceleradores (CNA, Spain)
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Vivo-Vilches, Carlos, López-Gutiérrez, José María, García-León, Manuel, Vockenhuber, Christof, and Walczyk, Thomas
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- 2017
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3. Certification of a 41Ca dose material for use in human studies (IRMM-3703) and a corresponding set of isotope reference materials for 41Ca measurements (IRMM-3701)
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Hennessy, Carmel, Berglund, Michael, Ostermann, Markus, Walczyk, Thomas, Synal, Hans-Arno, Geppert, Christopher, Wendt, Klaus, and Taylor, Philip D.P.
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- 2005
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4. Deciphering the iron isotope message of the human body
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Walczyk, Thomas and von Blanckenburg, Friedhelm
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- 2005
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5. Determination of chlorophyll in plant samples by liquid chromatography using zinc–phthalocyanine as an internal standard
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Bohn, Torsten and Walczyk, Thomas
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- 2004
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6. Iron bioavailability of a casein-based iron fortificant compared with that of ferrous sulfate in whole milk: a randomized trial with a crossover design in adult women.
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Henare, Sharon J, Nur Singh, Nadia, Ellis, Ashling M, Moughan, Paul J, Thompson, Abby K, and Walczyk, Thomas
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IRON metabolism ,ENRICHED foods ,ERYTHROCYTES ,BIOAVAILABILITY ,CASEINS ,COMPARATIVE studies ,CROSSOVER trials ,IRON ,IRON compounds ,ISOTOPES ,MILK ,HEALTH outcome assessment ,STATISTICAL sampling ,RANDOMIZED controlled trials ,DESCRIPTIVE statistics - Abstract
Background A highly soluble iron–casein complex has been developed for food fortification purposes with the aim to provide high iron bioavailability. Objective We aimed to determine the iron bioavailability of the iron–casein complex relative to that of ferrous sulfate (control) when given with whole milk in healthy young women. Methods A randomized comparator-controlled trial with a crossover design was conducted using the erythrocyte incorporation dual stable isotope (
57 Fe,58 Fe) technique. Iron absorption from the iron–casein complex was compared with that from ferrous sulfate in 21 healthy women aged 20–38 y with normal iron status. Results Fractional iron absorption (geometric mean; −SD, +SD) from the iron–casein complex (3.4%; 1.4%, 5.4%) and from ferrous sulfate (3.9%; 1.7%, 6.1%) were not statistically different (P > 0.05). The relative bioavailability value of the iron–casein complex to ferrous sulfate was determined to be 0.87 (−1 SD, +1 SD: −0.90, +2.64). Conclusions The iron–casein complex has iron bioavailability comparable to that of ferrous sulfate in healthy young women. This trial was registered at www.anzctr.org.au as ACTRN12615000690550. [ABSTRACT FROM AUTHOR]- Published
- 2019
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7. Inhibition of Iron Absorption by Calcium Is Modest in an Iron-Fortified, Casein- and Whey-Based Drink in Indian Children and Is Easily Compensated for by Addition of Ascorbic Acid.
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Walczyk, Thomas, Muthayya, Sumithra, Wegmüller, Rita, Thankachan, Prashanth, Sierksma, Aafje, Frenken, Leon G. J., Thomas, Tinku, Kurpad, Anura, and Hurrell, Richard F.
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PHYSIOLOGICAL effects of iron , *CALCIUM metabolism inhibitors , *ENRICHED foods , *IRON metabolism , *IRON in the body - Abstract
Background: Calcium inhibits and ascorbic acid (AA) enhances iron absorption from iron-fortified foods. Absorption efficiency depends on iron status, although the interaction is unclear. Objective: We investigated the ability of AA to overcome calcium-induced inhibition of iron absorption in children differing in iron status. Methods: The effect of calcium (0, 100, and 200 mg/test meal) on iron absorption in the absence and presence of AA (0, 42.5, and 85 mg/test meal) from a casein/whey-based drink fortified with ferrous sulfate was assessed in a series of randomized crossover studies both in iron-replete (IR) Indian schoolchildren and in children with iron deficiency anemia (IDA) (6-11 y; n = 14-16/group) by using stable isotopes. Results: In the absence of calcium and AA, iron absorption from the casein/whey-based drink was 20% lower in IR children than in children with IDA. The addition of calcium reduced mean iron absorption by 18-27%, with the effect being stronger for high added calcium (P< 0.01). AA at a 2:1 or 4:1 molar ratio enhanced iron absorption by a factor of 2-4 and greatly overcompensated for the inhibitory effect of calcium on iron absorption in a dose-dependent manner (P < 0.001). The dose-response effect tended to be stronger (P < 0.1) in the I DA group, and iron status was of far less influence on iron absorption than the enhancing effect of AA. Conclusion: When adding AA to iron-fortified milk products, care should be taken not to provide absorbable iron in excess of needs. [ABSTRACT FROM AUTHOR]
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- 2014
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8. Polyphenols and Phytic Acid Contribute to the Low Iron Bioavailability from Common Beans in Young Women.
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Nicolai6Petry, Egli, Ines, Zeder, Christophe, Walczyk, Thomas, and Hurrell, Richard
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POLYPHENOLS ,PHYTIC acid ,IRON deficiency diseases ,BEANS ,NUTRITION ,IRON content of food ,WOMEN'S nutrition - Abstract
Low iron absorption from common beans might contribute to iron deficiency in countries where beans are a staple food. High levels of phytic acid (PA) and polyphenols (PP) inhibit iron absorption; however, the effect of bean PP on iron absorption in humans has not been demonstrated and, with respect to variety selection, the relative importance of PP and PA is unclear. To evaluate the influence of bean PP relative to PA on iron absorption in humans, 6 stable iron isotope absorption studies were conducted in women (16 or 17 per study). Bean PP (20, 50, and 200 mg) were added in studies 1- 3 as red bean hulls to a bread meal. Studies 4- 6 investigated the influence on iron absorption of PP removal and dephytinization of whole red bean porridge and PP removal from dephytinized porridge. Iron absorption was lowered by 14% with 50 mg PP (P < 0.051 and by 45% with 200 mg PP (P < 0.001). The mean iron absorption from whole bean porridge was 2.5%. PP and PA removal increased absorption 2.6-fold (P< 0.001) and removal of PP from dephytinized porridge doubled absorption (P < 0.0011. Between-study comparisons indicated that dephytinization did not increase iron absorption in the presence of PP, but in their absence, absorption increased 3.4-fold (P < 0.001). These data suggest that in countries where beans are a staple food, PP and PA concentrations should be considered when selecting bean varieties for human consumption. Lowering only one inhibitor will have a modest influence on iron absorption. [ABSTRACT FROM AUTHOR]
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- 2010
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9. Ferritin-Iron Is Released during Boiling and In Vitro Gastric Digestion.
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Hoppler, Matthias, Schonbàchler, Andrea, Meile, Leo, Hurrell, Richard F., and Walczyk, Thomas
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FERRITIN ,IRON in the body ,CARRIER proteins ,HYDROGEN-ion concentration ,INDIGESTION ,LEGUMES ,BIOCHEMISTRY ,ESCHERICHIA coli ,BLOOD diseases - Abstract
Biofortification of staple foods with iron in the form of ferritin-iron is a promising approach to fighting iron-deficiency anemia in developing countries. However, contradictory results regarding iron bioavailability to humans from ferritin are not yet fully clarified. Furthermore, the question has been raised whether ferritin can potentially survive gastric passage intact and be absorbed via a ferritin-specific uptake mechanism. We studied changes of ferritin-iron and protein during cooking and in vitro gastric digestion. Water soluble, native ferritin-iron, measured in different legumes, represented 18% (soybeans) up to maximally 42% (peas) of total seed iron. Ferritin-iron was no longer detectable after boiling the legumes for 50 min in excess water. When the same cooking treatment was applied to recombinant bean ferritin propagated in Escherichia coli, some ferritin-iron remained measurable. During in vitro gastric digestion of recombinant bean ferritin and red kidney bean extract, ferritin-iron was fully released from the protein and dissolved at pH 2. Stability tests at varying pH at 37°C showed that the release of ferritin-iron starts at pH 5 and is complete at pH 2. We concluded that ferritin-iron is efficiently released from the ferritin molecule during cooking and at gastric pH and that it should be absorbed as efficiently as all other nonheme iron in food. [ABSTRACT FROM AUTHOR]
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- 2008
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10. Nonheme iron absorption in young women is not influenced by purified sulfated and unsulfated glycosaminoglycans.
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Storcksdieck genannt Bonsmann, Stefan, Walczyk, Thomas, Renggli, Sabine, and Hurrell, Richard F
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Meat is a well-known enhancer of iron absorption, yet the molecular entity mediating the effect remains obscure. Recently published data indicate that highly acidic sulfated glycosaminoglycans (GAG) from fish and chicken muscle are effective stimulants of iron uptake in Caco-2 cells. Two fully randomized stable isotope studies with crossover design were performed in a group of 16 apparently healthy young women to assess the effect of purified sulfated and unsulfated GAG on human iron absorption. Iron absorption was measured on the basis of erythrocyte incorporation of (57)Fe or (58)Fe 14 d after the administration of labeled semisynthetic meals (SSM) based on egg albumin, corn oil, maltodextrin, and water. The meals were consumed with or without added sodium hyaluronate (NaH, 300 mg) or chondroitin sulfate (CS, 360 mg) as representative unsulfated and sulfated GAG, respectively. The level of GAG added was 3 times (NaH) to about 10 times (CS), the amount expected to be present in 150 g beef muscle. Geometric mean iron absorption from SSM containing NaH (21.2%) or CS (19.4%) did not differ from that of SSM without GAG (19.5 and 20.3%, respectively). NaH and CS at those levels do not affect human nonheme iron absorption. [ABSTRACT FROM AUTHOR]
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- 2007
11. Nonheme Iron Absorption in Young Women Is Not Influenced by Purified Sulfated and Unsulfated Glycosaminoglycans.
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Genannt Bonsmann, Stefan Storcksdieck, Walczyk, Thomas, Renggli, Sabine, and Hurrell, Richard F.
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IRON , *ABSORPTION , *YOUNG women , *GLYCOSAMINOGLYCANS , *MUCOPOLYSACCHARIDES , *ANIMAL products , *NATIVE element minerals , *STIMULANTS , *ERYTHROCYTES - Abstract
Meat is a well-known enhancer of iron absorption, yet the molecular entity mediating the effect remains obscure. Recently published data indicate that highly acidic sulfated glycosaminoglycans (GAG) from fish and chicken muscle are effective stimulants of iron uptake in Caco-2 cells. Two fully randomized stable isotope studies with crossover design were performed in a group of 16 apparently healthy young women to assess the effect of purified sulfated and unsulfated GAG on human iron absorption. Iron absorption was measured on the basis of erythrocyte incorporation of 57Fe or 58Fe 14 d after the administration of labeled semisynthetic meals (SSM( based on egg albumin, corn oil, maltodextrin, and water. The meals were consumed with or without added sodium hyaluronate (NaH, 300 mg) or chondroitin sulfate (CS, 360 mg) as representative unsulfated and sulfated GAG, respectively. The level of GAG added was 3 times (NaH) to about 10 times (CS), the amount expected to be present in 150 g beef muscle. Geometric mean iron absorption from SSM containing NaH (21.2%( or CS (19.4%) did not differ from that of SSM without GAG (19.5 and 20.3%, respectively). NaH and CS at those levels do not affect human nonheme iron absorption. [ABSTRACT FROM AUTHOR]
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- 2007
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12. Chili, but not turmeric, inhibits iron absorption in young women from an iron-fortified composite meal.
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Tuntipopipat, Siriporn, Judprasong, Kunchit, Zeder, Christophe, Wasantwisut, Emorn, Winichagoon, Pattanee, Charoenkiatkul, Somsri, Hurrell, Richard, and Walczyk, Thomas
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CHILI powder ,TURMERIC ,CAPSAICIN ,PHENOLS ,IRON content of food ,IRON deficiency anemia ,GALLIC acid ,GASTRIC acid ,YOUNG women ,IRON metabolism ,COMPARATIVE studies ,CROSSOVER trials ,DIET ,DIETARY supplements ,HOT peppers ,INTESTINAL absorption ,ISOTOPES ,RESEARCH methodology ,MEDICAL cooperation ,PLANTS ,RESEARCH ,STATISTICAL sampling ,VEGETABLES ,EVALUATION research ,RANDOMIZED controlled trials ,CURCUMIN - Abstract
Chili and turmeric are common spices in indigenous diets in tropical regions. Being rich in phenolic compounds, they would be expected to bind iron (Fe)(3) in the intestine and inhibit Fe absorption in humans. Three experiments were conducted in healthy young women (n = 10/study) to assess the effect of chili and turmeric on Fe absorption from a rice-based meal containing vegetables and iron fortified fish sauce in vivo. Iron absorption was determined by erythrocyte incorporation of stable isotope labels ((57)Fe/(58)Fe) using a randomized crossover design. Addition of freeze-dried chili (4.2 g dry powder, 25 mg polyphenols as gallic acid equivalents) reduced Fe absorption from the meal by 38% (6.0% with chili vs. 9.7% without chili, P = 0.0017). Turmeric (0.5 g dry powder, 50 mg polyphenols as gallic acid equivalents) did not inhibit iron absorption (P = 0.91). A possible effect of chili on gastric acid secretion was indirectly assessed by comparing Fe absorption from acid soluble [(57)Fe]-ferric pyrophosphate relative to water soluble [(58)Fe]-ferrous sulfate from the same meal in the presence and absence of chili. Chili did not enhance gastric acid secretion. Relative Fe bioavailability of ferric pyrophosphate was 5.4% in presence of chili and 6.4% in absence of chili (P = 0.47). Despite the much higher amount of phenolics in the turmeric meal, it did not affect iron absorption. We conclude that both phenol quality and quantity determine the inhibitory effect of phenolic compounds on iron absorption. [ABSTRACT FROM AUTHOR]
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- 2006
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13. Iron status and food matrix strongly affect the relative bioavailability of ferric pyrophosphate in humans.
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Moretti, Diego, Zimmermann, Michael B., Wegmüller, Rita, Walczyk, Thomas, Zeder, Christophe, and Hurrell, Richard F.
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Background: Although ferric pyrophosphate is a promising compound for iron fortification of foods, few data are available on the effect of food matrices, processing, and ascorbic acid on its bioavailability. Objective: We compared the relative bioavailability (RBV) of ferrous sulfate in an experimental form of micronized dispersible ferric pyrophosphate (MDFP) in a wheat-milk infant cereal given with and without ascorbic acid with the RBV of MDFP from a processed and unprocessed rice meal. Design: A crossover design was used to measure iron absorption in young women (n = 26) from test meals fortified with isotopically labeled [
57 Fe]-MDFP and [58 Fe]-ferrous sulfate, based on erythrocyte incorporation of stable isotope labels 14 d later. Results: Geometric mean iron absorption from the wheat-based meal fortified with MDFP was 2.0% and that from the meal fortified with ferrous sulfate was 3.2% (RBV=62). The addition of ascorbic acid at a molar ratio of 4:1 to iron increased iron absorption from MDFP to 5.8% and that from ferrous sulfate to 14.8% (RBV = 39). In the rice meals, mean iron absorption fromMDFPadded to the rice at the time of feeding was 1.7%, and that from ferrous sulfate was 11.6% (RBV=15). The mean iron absorption from MDF Pextruded into artificial rice grains was 3.0% and that from ferrous sulfate in unprocessed rice was 12.6% (RBV = 24). Sixteen of 26 subjects were iron deficient. Iron status was a highly significant predictor of the RBV of MDFP (P < 0.001). Conclusion: RBV of the experimental MDFP varied markedly with food matrix and iron status. Assigning a single RBV value to poorly soluble compounds may be of limited value in evaluating their suitability for food fortification. [ABSTRACT FROM AUTHOR]- Published
- 2006
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14. Sodium iron EDTA [NaFe(III)EDTA] as a food fortificant: erythrocyte incorporation of iron and apparent absorption of zinc, copper, calcium, and magnesium from a complementary food based on wheat and soy in healthy infants.
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Davidsson, Lena, Ziegler, Ekhard, Zeder, Christophe, Walczyk, Thomas, and Hurrell, Richard
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Background: Phytic acid is a strong inhibitor of iron absorption from fortified foods. In adults, this inhibitory effect can be overcome by adding ascorbic acid with the iron fortificant or by using a "protected" iron compound such as NaFeEDTA. In addition, the use of NaFeEDTA as an iron fortificant has been reported to increase zinc absorption in adult women. No information is available on iron bioavailability from NaFeEDTA or the influence of NaFeEDTA on minerals and trace elements in infants. Objective: We aimed to compare iron bioavailability from a complementary food based on wheat and soy fortified with either NaFeEDTA or ferrous sulfate plus ascorbic acid. The apparent absorption of zinc, copper, calcium, and magnesium was evaluated in parallel. Design: Stable-isotope techniques were used in a crossover design to evaluate erythrocyte incorporation of iron 14 d after administration of labeled test meals and the apparent absorption of zinc, copper, calcium, and magnesium on the basis of fecal monitoring in 11 infants. Results: Geometric mean erythrocyte incorporation of iron was 3.7% (NaFeEDTA) and 4.9% (ferrous sulfate plus ascorbic acid) (P = 0.08). No significant differences in the apparent absorption of zinc, copper, calcium, or magnesium were observed between test meals (n = 10). Conclusions: Iron bioavailability from a high-phytate, cereal-based complementary food fortified with either NaFeEDTA or ferrous sulfate plus ascorbic acid was not significantly different. NaFeEDTA did not influence the apparent absorption of zinc, copper, calcium, or magnesium. NaFeEDTA does not provide any nutritional benefit compared with the combination of a highly bioavailable iron compound and ascorbic acid. [ABSTRACT FROM AUTHOR]
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- 2005
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15. Helicobacter pylori infection, iron absorption, and gastric acid secretion in Bangladeshi children.
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Sarker, Shafiqul A., Davidsson, Lena, Mahmud, Hasan, Walczyk, Thomas, Hurrell, Richard F., Gyr, Niklaus, and Fuchs, George J.
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Background: Nonheme-iron absorption requires an acidic milieu. Reduced gastric acid output as a consequence of Helicobacter pylori infection could be an important limiting factor for iron absorption. Objective: We measured gastric acid output and iron absorption from a non-water-soluble iron compound (ferrous fumarate) and a water-soluble iron compound (ferrous sulfate) in children with and without H. pylori infection. Design: Gastric acid output was quantified before (basal acid output, or BAO) and after pentagastrin stimulation (stimulated acid output, or SAO) in 2-5-y-old children with iron deficiency anemia who were (n=13) or were not (n=12) infected with H. pylori. Iron absorption was measured by using a double-stable-isotope technique. H. pylori-infected children were studied before and after eradication therapy. Results: BAO and SAO were significantly lower in the H. pylori- infected children (0.2 ± 0.2 and 1.6 ± 0.9 mmol/h, respectively) than in the uninfected children (0.9 ± 0.7 and 3.1 ± 0.9 mmol/h, respectively; P=0.01 and P<0.005). BAO and SAO improved to 0.8 ± 1.3 and 3.3 ± 2.4 mmol/h, respectively, after therapy. Iron absorption from ferrous sulfate was significantly greater than that from ferrous fumarate both before (geometric x: 19.7% compared with 5.3%; P<0.0001) and after (22.5% compared with 6.4%; P< 0.0001) treatment in H. pylori-infected children. Corresponding values for uninfected children were 15.6% and 5.4%, respectively (P < 0.001; n = 12). Conclusions: Iron absorption from ferrous fumarate was significantly lower than that from ferrous sulfate in both H. pylori-infected and uninfected Bangladeshi children. Treatment of H. pylori infection improved gastric acid output but did not significantly influence iron absorption. The efficacy of ferrous fumarate in iron fortification programs to prevent iron deficiency in young children should be evaluated. [ABSTRACT FROM AUTHOR]
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- 2004
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16. Dephytinization of a complementary food based on wheat and soy increases zinc, but not copper, apparent absorption in adults.
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Egli, Ines, Davidsson, Lena, Zeder, Christophe, Walczyk, Thomas, and Hurrell, Richard
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ZINC ,COPPER ,PHYTIC acid ,STABLE isotopes ,FOOD combining ,NUTRITION - Abstract
Complementary foods based on cereals may contain high amounts of phytic acid, which binds strongly to minerals and trace elements. The objective of the study was to evaluate the effect of dephytinization of a cereal-based complementary food on zinc and copper apparent absorption in adults. A dephytinized complementary food (<0.03 mg phytic acid/g) and one containing the native phytic acid concentration (4 mg/g) were labeled extrinsically with stable isotopes ((70)Zn and (65)Cu). Apparent zinc and copper absorption was based on fecal excretion of nonabsorbed labels in 9 adults, using a crossover design. Stable isotopes were quantified by thermal ionization MS. Apparent fractional zinc absorption was significantly higher (P = 0.005; Student's paired t test) from the dephytinized complementary food (34.6 +/- 8.0%; mean +/- SD) than from the complementary food with native phytic acid concentration (22.8 +/- 8.8%). Apparent fractional copper absorption did not differ (P = 0.167; 19.7 +/- 5.1% dephytinized vs. 23.7 +/- 8.1% native phytic acid). These results clearly demonstrate the beneficial effect of dephytinization of a complementary food on fractional absorption of zinc but not of copper in adults. The long-term nutritional benefits of dephytinization of complementary foods should be evaluated in young children. [ABSTRACT FROM AUTHOR]
- Published
- 2004
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17. Phytic acid added to white-wheat bread inhibits fractional apparent magnesium absorption in humans.
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Bohn, Torsten, Davidsson, Lena, Walczyk, Thomas, and Hurrell, Richard F.
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Background: Phytic acid has been reported to impair the absorption of minerals and trace elements such as calcium, zinc, and iron in humans. However, limited information is available on the effect of phytic acid on magnesium absorption. Objective: The objective was to evaluate the effect of phytic acid on fractional apparent magnesium absorption in humans. Design: Two stable-isotope studies were performed with 8-9 healthy adults per study. Test meals were based on 200 g phytic acid-free wheat bread; test meals with and without added phytic acid were served on days 1 and 3 according to a crossover design. Phytic acid was added in amounts similar to those naturally present in whole-meal (1.49 mmol) and in brown bread (0.75 mmol). Each test meal was labeled with 0.7 mmol
25 Mg or 1.1 mmol26 Mg. The total magnesium content was standardized to 3.6 mmol in all test meals. Apparent magnesium absorption was based on fecal monitoring. Results: The addition of phytic acid lowered fractional apparent magnesium absorption from 32.5 ± 6.9% (no added phytic acid) to 13.0 ± 6.9% (1.49 mmol added phytic acid; P < 0.0005) and from 32.2 ± 12.0% (no added phytic acid) to 24.0 ± 12.9% (0.75 mmol added phytic acid;P<0.01). The inhibiting effect of phytic acid was dose dependent (P < 0.005). Conclusion: The results show that fractional magnesium absorption from white-wheat bread is significantly impaired by the addition of phytic acid, in a dose-dependent manner, at amounts similar to those naturally present in whole-meal and brown bread [ABSTRACT FROM AUTHOR]- Published
- 2004
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18. Measurement of magnesium absorption and retention in type 2 diabetic patients with the use of stable isotopes.
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Wälti, Monika K., Zimmermann, Michael B., Walczyk, Thomas, Spinas, Giatgen A., and Hurrell, Richard F.
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Background: Magnesium deficiency has been associated with type 2 diabetes and may reduce insulin sensitivity and impair glucose tolerance. The etiology of magnesium depletion in diabetes is unclear. Animal studies suggest that diabetes may impair magnesium absorption; however, there are no published data on magnesium absorption in humans with diabetes. Objective: Magnesium absorption from a test meal and the excretion and retention of magnesium were compared between patients with type 2 diabetes and healthy control subjects. Design: A meal labeled with 10 mg 26Mg isotopic label was administered, and stool and urine samples were collected for 10 and 6 d, respectively. Apparent absorption was calculated as the difference between the oral dose of 26Mg isotopic label and the total amount of the isotopic label excreted in the feces. Magnesium retention was calculated from the apparent absorption and urinary excretion of 26Mg isotopic label in the 6 d after administration. Results: Mean (± SD) values for fractional magnesium absorption in the diabetic patients and the control subjects were 59.3 ± 7.0% and 57.6 ± 8.5%, respectively (NS). Mean (± SD) urinary magnesium excretion values in the diabetic patients and the control subjects were 11.2 ± 2.6% and 11.7 ± 3.8%, respectively (NS); retention values were 54.2 ± 7.1% and 51.4 ± 6.1%, respectively (NS). Conclusion: Dietary magnesium absorption and retention are not impaired in patients with reasonably well-controlled type 2 diabetes. [ABSTRACT FROM AUTHOR]
- Published
- 2003
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19. Iron absorption from fish sauce and soy sauce fortified with sodium iron EDTA.
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Fidler, Meredith C., Davidsson, Lena, Walczyk, Thomas, and Hurrell, Richard F.
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Background: Fish sauce and soy sauce have been suggested as food vehicles for iron fortification in Asia. NaFeEDTA is a potentially useful fortificant because it can be added to these condiments without causing precipitation during storage. Objectives: The objectives were to evaluate iron absorption from NaFeEDTA-fortified fish sauce and soy sauce against a reference fortificant (FeSO
4 ), to compare iron absorption from NaFeEDTA-fortified fish sauce and soy sauce, and to evaluate the influence of fish sauce and soy sauce per se on iron absorption. Design: Five separate iron-absorption studies were made in adult women (10 women per study). Iron absorption was measured on the basis of erythrocyte incorporation of57 Fe or58 Fe 14 d after the intake of labeled meals of rice or rice and vegetables. Fish sauce or soy sauce (10 g) fortified with 5 mg Fe as NaFeEDTA or FeSO4 was fed with selected meals. The results are presented as geometric means. Results: Iron absorption from NaFeEDTA- and FeSO4-fortified fish sauce (3.3% and 3.1%, respectively) and soy sauce (6.1% and 5.6%, respectively) was not significantly different. No significant difference was observed when NaFeEDTA-fortified fish sauce and soy sauce were compared directly (6.7% and 7.9%, respectively). Soy sauce inhibited iron absorption from rice-based meals (8.5% without and 6.0% with soy sauce; P < 0.02), whereas fish sauce did not affect iron absorption significantly. Conclusion: The relatively high iron absorption from NaFeEDTA-fortified fish sauce and soy sauce and the acceptable organoleptic properties of NaFeEDTA indicate the potential usefulness of this iron fortificant in fish sauce and soy sauce fortification programs. [ABSTRACT FROM AUTHOR]- Published
- 2003
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20. No enhancing effect of vitamin A on iron absorption in humans.
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Walczyk, Thomas, Davidsson, Lena, Rossander-Hulthen, Lena, Hallberg, Leif, and Hurrell, Richard F.
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Background: Vitamin A and β-carotene were recently reported to enhance iron absorption by counteracting the inhibitory effect of phytic acid in cereal-based meals and of polyphenol-containing beverages on nonheme-iron absorption in humans. Objective: Our objective was to further evaluate the influence of vitamin A on iron absorption. Design: Iron absorption from corn bread with or without added vitamin A (retinyl palmitate) was determined in 5 studies in young adult human subjects by using either a stable-isotope method (2 studies) or a radioisotope technique (3 studies). Iron absorption was measured by erythrocyte incorporation of the isotopic labels and by whole-body retention of
59 Fe. Corn bread was served with water (studies 1 and 3) or coffee (studies 2, 4, and 5). The studies differed in the amounts and chemical forms of added tracer and fortification iron. The possibility of methodologic artifacts in earlier investigations was evaluated. Results: No effect of vitamin A on iron absorption from the test meals was identified in the individual studies by using paired Student's t test. A slightly negative effect of vitamin A on iron absorption was found with the use of analysis of variance. Conclusions: The previously reported findings of a positive effect of vitamin A on nonheme-iron absorption in humans was not confirmed. Incomplete isotopic equilibration of the tracer with native iron in the meal or with fortification iron cannot explain the previous findings. However, the present study does not exclude the possibility that suboptimal vitamin A status influences the effect of dietary vitamin A on iron absorption. [ABSTRACT FROM AUTHOR]- Published
- 2003
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21. Iron bioavailability from iron-fortified Guatemalan meals based on corn tortillas and black bean paste.
- Author
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Davidsson, Lena, Dimitriou, Triantafillia, Boy, Erick, Walczyk, Thomas, and Hurrell, Richard F.
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Background: Corn masa flour is widely consumed in Central America and is therefore a potentially useful vehicle for iron fortification. Objective: The goal was to evaluate the bioavailability of iron from meals based on corn tortillas and black bean paste that were fortified with ferrous fumarate, ferrous sulfate, or NaFeEDTA and to investigate the potential of Na
2 EDTA to increase the bioavailability of iron from ferrous fumarate. Design: With use of a crossover study design, iron bioavailability was measured in Guatemalan girls aged 12-13 y by a stable-isotope technique based on erythrocyte incorporation 14 d after intake. Results: Geometric mean iron bioavailability from test meals fortified with ferrous fumarate was 5.5-6.2% and was not improved significantly by the addition of Na2 EDTA at molar ratios of 1:1 relative to fortification iron or to the total iron content of the fortified corn masa flour. Geometric mean iron bioavailability from test meals fortified with ferrous sulfate was 5.5% and was significantly higher in test meals fortified with NaFeEDTA (9.0%; P = 0.009, paired t test). Conclusions: The bioavailability of iron from ferrous fumarate was not improved by the addition of Na2 EDTA, contrary to what was previously shown for ferrous sulfate in other cereal-based meals. However, the bioavailability of iron from the test meal was significantly enhanced when NaFeEDTA replaced ferrous sulfate. These results support the use of NaFeEDTA in the fortification of inhibitory staple foods such as corn masa flour. Am J Clin Nutr 2002;75:535-9. [ABSTRACT FROM AUTHOR]- Published
- 2002
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22. Improving iron absorption from a Peruvian school breakfast meal by adding ascorbic acid or Na2EDTA.
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Davidsson, Lena, Walczyk, Thomas, Zavaleta, Nelly, and Hurrell, Richard F.
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PHYSIOLOGICAL effects of iron ,ABSORPTION (Physiology) ,VITAMIN C ,ETHYLENEDIAMINETETRAACETIC acid ,BREAKFASTS ,HEALTH of school children ,IRON deficiency diseases in children - Abstract
Background: Iron-fortified school breakfasts have been introduced in Peru to combat childhood iron deficiency. Objective: We evaluated whether iron absorption from a school breakfast meal was improved by increasing the ascorbic acid content or by adding an alternative enhancer of iron absorption, Na
2 EDTA. Design: In a crossover design, iron absorption from test meals was evaluated by erythrocyte incorporation of58 Fe and57 Fe. The test meals (wheat bread and a drink containing cereal, milk, and soy) contained 14 mg added Fe (as ferrous sulfate) including 2.0-2.6 mg58 Fe or 4.0-7.0 mg57 Fe. Results: Geometric mean iron absorption increased significantly from 5.1% to 8.2% after the molar ratio of ascorbic acid to fortification iron was increased from 0.6:1 to 1.6:1 (P < 0.01; n = 9). Geometric mean iron absorption increased significantly from 2.9% to 3.8%, from 2.2% to 3.5%, and from 2.4% to 3.7% after addition of Na2 EDTA at molar ratios relative to fortification iron of 0.3:1, 0.7:1, and 1:1, respectively, compared with test meals containing no added enhancers (P < 0.01; n = 10 for all). Iron absorption after addition of ascorbic acid (molar ratio 0.6:1) was not significantly different from that after addition of Na2 EDTA (molar ratio 0.7:1). Conclusions: Ascorbic acid and Na2 EDTA did not differ significantly in their enhancing effects on iron absorption at molar ratios of 0.6:1 to 0.7:1 relative to fortification iron. Additional ascorbic acid (molar ratio 1.6:1) increased iron absorption significantly. Increasing the molar ratio of Na2 EDTA to fortification iron from 2 0.3:1 to 1:1 had no effect on iron absorption. [ABSTRACT FROM AUTHOR]- Published
- 2001
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23. Influence of ascorbic acid on iron absorption from an iron-forified, chocolate-flavored...
- Author
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Davidsson, Lena, Walczyk, Thomas, Morris, Audrey, and Hurrell, Richard F.
- Subjects
CHILDREN'S health ,VITAMIN C ,CHOCOLATE drinks ,MILK ,HEALTH - Abstract
Provides information on a study which evaluated the influence of ascorbic acid on iron absorption from an iron-fortified, chocolate flavored milk drink on Jamaican children who have anemia. Method used to carry out the study; Background information on the findings from the study.
- Published
- 1998
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24. OC1. Translating a novel urine test for early detection and accurate assessment of bone abnormalities.
- Author
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Hillegonds, Darren, Fitzgerald, Robert, Burton, Douglas, Yang, Meng, Walczyk, Thomas, Vijayakumar, Srinivasan, Herold, David, Deftos, Leonard, and Vogel, John
- Published
- 2008
- Full Text
- View/download PDF
25. Iridium isotope ratio measurements by negative thermal ionization mass spectrometry and atomic weight of iridium
- Author
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Walczyk, Thomas and Heumann, Klaus G.
- Published
- 1993
- Full Text
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26. Low blank rhenium isotope ratio determinations by V 2O 5 coated nickel filaments using negative thermal ionization mass spectrometry
- Author
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Walczyk, Thomas, Hebeda, Erhard H., and Heumann, Klaus G.
- Published
- 1994
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27. Osmium isotope ratio determinations by negative thermal ionization mass spectrometry
- Author
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Völkening, Joachim, Walczyk, Thomas, and G. Heumann, Klaus
- Published
- 1991
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28. Iron isotope ratio measurements by negative thermal ionisation mass spectrometry using FeF 4− molecular ions
- Author
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Walczyk, Thomas
- Published
- 1997
- Full Text
- View/download PDF
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