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Nuclear Medicine Unit, Faculty of Medicine, University of Ruhuna, Galle, Sri Lanka and * U.S. Department of Agriculture/ARS Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine and Texas Children’s Hospital, Houston, TX, 77030
2To whom correspondence should be addressed. E-mail: sabrams{at}bcm.tmc.edu.
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ABSTRACT |
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 TOP ABSTRACT SUBJECTS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
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KEY WORDS: • fortification • rice flour • Sri Lanka • iron absorption • zinc absorption
Strategies used to combat micronutrient deficiencies worldwide include fortification of staples, supplementation, modification of traditional diets, and recently, fortified beverages (1). Like many developing countries, Sri Lanka has a high prevalence of deficiencies in micronutrients such as iron, zinc, and iodine, particularly in young women and poor laborers in tea plantations in the interior of the country (2–5). In an analysis using national food balance data to estimate the prevalence of zinc deficiency in various regions of the world, Brown et al. (6) reported that populations in southern Asia, including Sri Lanka, have the lowest daily intake of zinc (0.8 mg/d) worldwide. They estimated that 95.4% of the people in southern Asia are at risk for zinc deficiency. Approaches to resolving this problem, including a pill supplementation program and wheat flour fortification, were considered but not adopted in Sri Lanka. Although pill supplementation is considered to be useful for short-term interventions such as during pregnancy (7), it is not considered to be sufficiently sustainable for the population as a whole. Wheat flour has been used as a vehicle in many countries for food fortification, but the lack of local processing and the low per capita consumption of this staple by target groups make it unsuitable for this purpose in other nations, including Sri Lanka (8).
Rice is a potential vehicle for fortification because of its widespread consumption by at-risk populations (9). However, rice is more difficult to fortify because much of the production of this grain is not centrally processed. In addition, to fortify the rice, it is necessary to use techniques such as parboiling in which the rough rice is pretreated by boiling and then heating and drying. This is expensive and results in discoloration that may be unacceptable to consumers. Enriched premixes that are sprayed on the rice along with a protective coating are possible, but similarly require central processing. In powder enrichment in which micronutrients are added to the rice after processing, there can be a substantial loss of nutrients if the rice is rinsed before cooking (10). As a result of these limitations, a novel approach was tested in this study, i.e., the fortification of rice flour instead of grain rice. In Sri Lanka, rice flour in various forms is centrally processed at a limited number of locations, is approximately equal in cost to wheat flour, and is growing in popularity. Although fortification of rice flour was proposed in countries including the Philippines and Guyana in which consumption of rice flour is high (9,10), its bioavailability has not been tested.
Most Sri Lankans eat rice as their primary dietary staple and have a low intake of animal products; it is thought that this diet may contribute to a high prevalence of multiple micronutrient deficiencies. In addition, the presence of high levels of inhibitors such as phytates and polyphenols in their plant-based diet decreases mineral absorption (11) by forming insoluble complexes in the gastrointestinal tract. It was shown (12–14) that the addition of Na2EDTA significantly improves the fractional absorption of ferrous sulfate. Fewer studies exist that document the positive effects of Na2EDTA (15) or NaFeEDTA (16) on zinc absorption.
Therefore, we sought to evaluate rice flour as a possible vehicle for a national food fortification program in Sri Lanka. Our primary objective was to measure iron and zinc bioavailability from a locally prepared, rice flour–based meal fortified with iron, zinc, and folate using stable isotope techniques. To test the efficacy of Na2EDTA in overcoming the inhibitory effects of phytates and polyphenols, we included 2 groups in our study that received Na2EDTA at a molar ratio of 1:1 of Fe:Na2EDTA, a ratio that was shown to be both efficacious and safe in previous studies (14). Ferrous sulfate (FeSO4) and zinc oxide (ZnO) were chosen as the iron and zinc fortificant sources because of their established bioavailability and widespread availability (17).
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SUBJECTS AND METHODS |
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TOPABSTRACTSUBJECTS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
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All subjects were given 75 g fortified rice flour/d to be consumed for a period of 2 wk before the absorption trial. Although it was not a specific objective of the project, a pilot efficacy trial over a period of 1 mo was accomplished by providing fortified rice flour on a daily basis to the 4 groups of subjects. Baseline and final biochemical variables of the subjects were compared after providing the appropriately fortified rice flour for an additional 2 wk beyond the intended "run-in" period of 14 d.
On d 14, all children arrived at the testing site at 0630 h after fasting overnight except for water. A reference iron isotope dose was administered that consisted of 5 mg 57Fe as iron sulfate dissolved in orange juice with 50 mg of ascorbic acid added. The following morning, after an overnight fast, each subject was given a test meal prepared with labeled stable isotopes according to their group allocation. They fasted for an additional 2 h and then resumed their usual diet. Subsequently, 70Zn was given intravenously to subjects of groups 3 and 4 who had been receiving zinc-fortified rice flour.
Approximately 72 h after the test meal, 25 mL of urine was collected in urine collection bags from subjects in groups 3 and 4. These samples were transported to Baylor College of Medicine for measurement of fractional excretion of zinc. Fortified rice flour was supplied to the subjects for another 2 wk. On d 14 after the isotope administration, a venous blood sample (5 mL) was obtained for the determination of Hb, ferritin, zinc, folate, and RBC iron isotope enrichment. Three subjects were unable to participate, and 2 subjects dropped out afterwards due to urgent family needs; 48 children completed the trial. Three blood samples for 57Fe and 58Fe were contaminated during transport and insufficient 58Fe was available to provide an adequate dose to 2 subjects. Therefore, 45 values were obtained for 57Fe, and 43 samples were analyzed for 58Fe enrichments. For zinc absorption, 24 samples were evaluated.
Rice flour and isotope preparation. Country brown rice was used for fortification. Grade 2 (well polished, 6–8% weight reduction on polishing) rice was powdered to 300–500 mesh size using an electric grinder at the Industrial Technology Institute, Colombo, Sri Lanka. Mixing of food-grade minerals with rice flour was accomplished at the ITI using a ribbon blender; iron and zinc levels were measured by flame atomic absorption spectrometry (AAS).
57Fe, 58Fe, 67Zn, and 70Zn were obtained from Trace Sciences International. The 67Zn (90% enrichment by mass) was obtained as zinc oxide dry powder, and 70Zn (90% enrichment by mass) was prepared in an aqueous solution of 0.085 g/L and then tested for sterility and pyrogenicity at the Investigational Pharmacy of Texas Children’s Hospital, Houston, TX.
57Fe (95% enrichment by mass) and 58Fe (96% enrichment by mass) were provided in elemental metal form. Iron isotope solution was prepared, as the sulfate, at the Faculty of Medicine, Galle, by dissolving metals in 0.03 mL of 7 mol/L nitric acid and 0.125 mL of 0.5 mol/L sulfuric acid for 1 mg of elemental iron. The solutions were dried at 120°C, at 230°C, and finally at 500°C for 30 min each in a muffle furnace. After cooling, the final products were resuspended in 0.2 mol/L sulfuric acid at 0.24 mL for 1 mg of iron. Deionized water was added to produce a solution yielding a unit dose of 1.5 mg elemental iron for each 2.5 mL of solution.
Test meal preparation. Each meal, which consisted of a local food called a "halapa," was individually prepared. Rice flour was weighed on a calibrated scale within ± 0.1 g of the desired weight (25 g). Each portion of rice flour was mixed with 15 mL of doubly distilled water and kneaded for 2–3 min until a smooth dough was produced. The dough was flattened on a leaf (Macaranga peltata) that is commonly used for flavoring in Sri Lanka. Next, 1.5 mg of elemental iron in the form of 58FeSO4 (all 4 groups), 9.627 mg of Na2EDTA (groups 2 and 4) and 1.5 mg of elemental zinc in the form of 67ZnO (groups 3 and 4) were spread over the dough. The exact dose was carefully measured and recorded with the subject’s identification number. The amount added was in the same proportion as the unlabeled, but fortified flour. A mixture of grated coconut (12 g) cooked in sugar syrup (10 g) was spread on the dough, and then the halapa was folded and steamed for 10 min. The steamed product was stored in a refrigerator and heated in the microwave oven just before the administration of the meal. The recipe for the "halapa" was as follows: 1) 25 g of rice flour (brown country rice, milled at 80% extraction, 500 mesh size) fortified with folate (2 mg/kg) and labeled with isotopes appropriate per group; 2) 15 mL distilled water; 3) 10 g sugar; 4) 12 g grated coconut; and 5) a pinch of salt.
The halapa was analyzed for micronutrient content, protein, fat, and carbohydrates using the Nutrition Data Systems for Research (v4.03) program. The analysis revealed that each halapa with added folate contained: 209 kcal (873 kJ); fat, 8.4 g (35% of energy); carbohydrate, 32 g (60% of energy); protein, 2.6 g (5% of energy); fiber, 3 g; folate, 55 µg; iron, 0.9 mg; and zinc, 0.9 mg. The levels of the iron and zinc levels were confirmed by AAS; the phytate level was measured by AOAC ’95 method (18) and was 22.5 mg/halapa.
Isotope methods. The details of isotope analysis were described previously (19,20). Iron isotope ratios were measured in the RBC at d 14. The iron isotope ratio was measured with a thermal ionization magnetic sector MS (MAT 261; Finnigan ThermoQuest, Bremen, Germany). The results were expressed as the ratio of 58Fe to 56Fe. The ratio of the 2 nonadministered isotopes (56Fe and 54Fe) was used to correct for temperature-specific differences in fractionation.
Urinary zinc isotope enrichments were measured similarly to the iron isotopes. Isotope ratios were expressed with respect to the nonadministered isotope, 66Zn, and corrected for differences in fractionation with the use of the 64Zn to66Zn ratio.
Iron incorporation of 58Fe into RBC at d 14 was measured as previously described (15). Iron absorption was calculated from iron incorporation, based on the assumption that 90% of the absorbed iron was incorporated into RBC. Zinc absorption was calculated from the relative fractional excretion of the oral and i.v. isotope doses in the 72-h urine samples.
Other methods. Hb concentration was measured by the cyanmethemoglobin method (21) using a spectrophotometer at the Nutrition Research Laboratory, Galle, Sri Lanka. Serum ferritin was measured by immunoradiometric assay with provision of reagents by North East Thames Regional Immunoassay (22) from St Bartholomew’s Hospital, London at the RIA Laboratory of the Nuclear Medicine Unit, Faculty of Medicine, Galle. Serum folate was measured by RIA technique with reagents from the Diagnostic Products Corporation (23), at the same institution. Serum zinc was analyzed at the Industrial Technology Institute, Colombo, Sri Lanka by flame atomic absorption spectrophotometry using standard solutions (24). The aqueous solution of 70Zn was tested for sterility and pyrogenicity using the quantitative chromogenic limulus amebocyte lystate test (QCL-1000 kit from BioWhittaker, BioWhittaker Molecular Applications) by the Investigational Pharmacy of Texas Children’s Hospital, Houston, TX.
Statistical analysis.
ANOVA was used to determine whether the groups differed using fractional absorption as the primary outcome variable. Changes in biochemical variables between the beginning and ending of the study were analyzed using paired t tests. Subgroup analysis (including gender) was accomplished using analysis of covariance. Outliers were tested using the method of Hadi. Based on the absorption from fortified wheat seen in a previous study in a similar population in Indonesia (14), the following assumptions were made in calculating the power required for the study: 1) ferrous sulfate absorption will be 15.9 ± 6.8% (mean ± SD); and 2) the addition of Na2EDTA will increase FeSO4 absorption by 50 to 
24 ± 7.0%.
A sample size of 18 was predicted to give >90% power (
= 0.05) to detect the assumed difference of 8% between the FeSO4 + Na2EDTA groups (total of 24) and the FeSO4 groups (total of 24). The additional 6 subjects in each group were added to accommodate drop-outs. Differences in iron and zinc absorption between groups were assessed using ANOVA and paired t tests. Statistical analysis was carried out using Stata 6.0 and Minitab 13.0. Anthropometry was calculated using Anthro version 1.02, 1999, CDC. Descriptive statistics are expressed as means ± SD or as geometric means. Differences with P-values < 0.05 were considered to be significant.
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RESULTS |
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TOPABSTRACTSUBJECTS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
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0.03) in their serum folate status at the end of the study (overall 6.58 nmol/L).
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The highest fractional absorption of Fe from the meal was in group 4, who consumed FeSO4 + Na2EDTA with zinc (6.1 ± 4.4%) and lowest in group 3 who consumed FeSO4 with zinc (1.9 ± 1.1%) (Table 3). Geometric means were slightly lower. Absorption of 58Fe from the test meal differed between group 2 (FeSO4 + Na2EDTA) and group 3 (FeSO4 + ZnO) P = 0.032; group 4 (FeSO4 + Na2EDTA + ZnO) and group 1 (FeSO4) P = 0.025; and group 4 (FeSO4 + Na2EDTA + ZnO) and group 3 (FeSO4 + ZnO) P = 0.005. The presence of zinc did not adversely affect absorption of 58Fe from the meal; in fact, the absorption was greater in groups 3 and 4 receiving zinc (3.8% ± 3.7) than in groups 1 and 2 not receiving zinc (3.0% ± 1.8), although this difference was not significant (P > 0.10). In a multivariate model of fractional absorption of 58Fe including group, initial ferritin, and Hb levels, age, sex, and weight, only group (P < 0.01) and sex (P = 0.02) were significant. Boys (4.4% ± 3.7) had a higher fractional absorption than girls (2.5% ± 1.5).
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DISCUSSION |
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TOPABSTRACTSUBJECTS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
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Based on the iron concentration in the fortified rice flour (60 mg/kg) and the absorption of added iron in the FeSO4 + Na2EDTA + ZnO group (6.1%), the children absorbed 92 µg of iron from the 25 g of rice flour in the test meal. This represents 13% of the estimated absorbed requirement (0.7–0.8 mg) of iron in this age group (26). Total absorption from added zinc in the Sri Lankan meal was 202 and 132 µg with and without Na2EDTA, respectively. This constitutes 17 and 11%, respectively, of the 1200 µg absorbed zinc needs of an 8-y-old child (27).
Various studies demonstrated the positive effects of Na2EDTA on iron absorption from FeSO4. Davidsson et al. (28) found that corn masa flour fortified with ferrous fumarate did not have enhanced fractional iron absorption with the addition of FeNaEDTA. However, absorption from FeSO4 increased when Na2EDTA was added at a molar ratio of 1:1. Hurrell et al. (14) measured iron absorption from weaning cereals fortified with FeSO4 with or without Na2EDTA. The range of fractional absorption measured (0.6–5.7%) was similar to that found in our study (1.9–6.1%), but the group that consumed Na2EDTA had 1.9–3.9 times greater absorption. Mendoza and associates (29) studied 14 nonanemic women who were given porridge made with both low-phytate maize and unmodified maize, fortified with either FeSO4 or NaFeEDTA. With low-phytate maize, fractional absorption was 1.9 (FeSO4 group) and 5.4% (NaFeEDTA group), whereas it was 1.7 and 5.7%, respectively, with unmodified maize. Fallahi et al. (15) reported that when female college students were given iron-fortified bread for 2 mo, the group administered NaFeEDTA as well as FeSO4 had a greater improvement in iron status than the group that were not administered the NaFeEDTA.
Davidsson et al. (30) and Fairweather-Tait et al. (31) found that there was no effect on zinc absorption in fortified weaning cereals when Fe was added. We were unable to verify this finding because all groups received iron; however, there was no adverse effect on iron absorption as a result of zinc fortification. We found a marginally significant interaction between Zn and Na2EDTA when comparing the effects of Na2EDTA on iron absorption. This interaction might indicate that Zn enhances the ability of Na2EDTA to bind iron. This is physiologically unlikely. Additionally, previous studies showed that Zn in high molar ratios can have deleterious effects on iron absorption (17,32,33). Therefore, it is reasonable to conclude that iron absorption was significantly improved in the presence of Na2EDTA.
Davidsson et al. (16) studied the effects of EDTA on zinc absorption in women consuming a meal of a wheat roll fortified with either FeSO4 or NaFeEDTA. Zinc absorption increased 60.3% in the group consuming NaFeEDTA. This was similar to the increase of 53.4% we found in this study.
Zinc absorption from the fortified rice flour was lower than anticipated, but fell within the lower end of the published range (6.4–55%) from a large number of populations and study designs. Using isotopic techniques similar to those utilized in this trial, we found 24% zinc absorption in Indonesian children who consumed a test meal of fortified wheat flour (17).
Studies in adults documented the inhibition by phytates of zinc absorption. Nävert et al. (34) noted a linear increase in zinc absorption from wheat rolls as the phytate level was decreased. Larsson et al. (35) found a similar result after dephytinization of malted and soaked oats. However, there very limited information exists concerning the existence of this relation in children. The low fractional absorption that we saw probably cannot be attributed solely to high phytate levels because the rice flour used in this study had relatively low phytate concentrations (i.e., 110 ± 10 mg/100 g) when measured by the AOAC ’95 method (18). The phytic acid concentration in the local rice depends on the variety (250–530 mg/100 g with an average of 320 mg/100 g); polishing (6–8% in our rice) will further reduce the phytate to a range of 80–330 mg/100 g (36). Because zinc absorption is increased during zinc deficiency, the relative adequacy of the zinc status of the population studied may have contributed to the low measured bioavailability. However, consideration should be given to evaluating either higher levels of zinc fortification or the use of dephytinization to provide a greater level of absorbed zinc in the fortified flour.
A limitation of our study is that we did not systematically evaluate the population acceptability and the long-term stability of the fortified rice flour product. However, neither the participants nor their families commented unfavorably about color or taste change during the course of the study. The unused flour was distributed among the families after the study, and the color of the cooked meals was acceptable even after storage in the heat and humidity of Sri Lanka for 2 mo. Given these favorable preliminary results, more formalized sensory testing is indicated and will be conducted at multiple levels of enrichment.
In summary, it appears that fortified rice flour can be considered to be a potentially effective strategy to ameliorate the prevalence of micronutrient malnutrition. There was general satisfaction with the product, although the bioavailability of iron and zinc was at the lower end of the range seen in previous studies. These findings demonstrate the importance of conducting bioavailability studies in countries in which food fortification programs are being considered. The regional differences in food preferences, levels of inhibitors, and individual physical characteristics of the inhabitants can make a large difference in the results reported in geographically diverse studies. Finally, Na2EDTA at a 1:1 mol/L ratio with iron and a 1:0.7 mol/L ratio with zinc improved the absorption of both iron and zinc.
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ACKNOWLEDGMENTS |
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FOOTNOTES |
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Manuscript received 28 June 2004. Initial review completed 22 July 2004. Revision accepted 26 August 2004.
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LITERATURE CITED |
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TOPABSTRACTSUBJECTS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
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1. Abrams, S. A., Mushi, A., Hilmers, D. C., Griffin, I. J., Davila, P. & Allen, L. (2003) A multinutrient-fortified beverage enhances the nutritional status of children in Botswana. J. Nutr. 133:1834-1840.
2. Mudalige, R. & Nestal, P. (1996) Prevalence of anaemia in Sri Lanka. Ceylon J. Med. Sci. 39:9-16.
3. De Silva, L.D.R. & Atukorale, T.M.S. (1996) Micronutrient status of plantation workers in Sri Lanka during pregnancy and post partum. J. Obstet. Gynaecol. Res. 22:239-234.[Medline]
4. Atukorala, T.M.S. & De Silva, L.D.R. (1990) Iron status of adolescent females in three schools in an urban area of Sri Lanka. J. Trop. Pediatr. 36:316-321.
5. Liyanage, K.D.C.E., Thabrew, M. I. & Goonaratne, C. (1995) Iron deficiency anaemia in children aged 09–24 months from a rural area of south of Sri Lanka. Sri Lanka Dent. J. 18:14-17.
6. Brown, K. H., Wuehler, S. E. & Peerson, J. E. (2001) The importance of zinc in human nutrition and estimation of the global prevalence of zinc deficiency. Food Nutr. Bull. 22:113-126.
7. Goonewardena, I.M.R., Liyanage, C. & Seekkuge, J. (1995) Antenatal iron status and its correlation to haemoglobin levels in pregnant women attending an antenatal clinic. Ceylon Med. J. 40:67-69.[Medline]
8. Status on iron fortification of wheat flour [Online] - http://www.sph.emory.edu/wheatflour/Test/Data_Evaluation/febr_04.xls [accessed September 15,2003].
9. Simmons, W. K. (1990) Food fortification in the English-speaking Caribbean. Food Nutr. Bull. 12 http://www.unu.edu/unupress/food/8F123e/8F123E08.htm [accessed September 15, 2003].
10. Food Fortification Project [Online] () Department of Health Republic of the Philippines http://www.doh.gov.ph/food/FF5.HTM [accessed September 15, 2003].
11. Hallberg, L., Rossander, L. & Skanberg, A. B. (1987) Phytates and the inhibitory effect of bran on iron absorption in man. Am. J. Clin. Nutr. 45:988-996.
12. MacPhail, A. P., Patel, R. C., Bothwell, T. H. & Lamparelli, R. D. (1994) EDTA and the absorption of iron from food. Am. J. Clin. Nutr. 59:644-648.
13. Davidsson, L., Walczyk, T., Zavaleta, N. & Hurrell, R. F. (2001) Improving iron absorption from a Peruvian school breakfast meal by adding ascorbic acid or Na2EDTA. Am. J. Clin. Nutr. 73:283-287.
14. Hurrell, R. F., Reddy, M. B., Burri, J. & Cook, J. D. (2000) An evaluation of EDTA compounds for iron fortification of cereal-based foods. Br. J. Nutr. 84:903-910.[Medline]
15. Ebrahim, F., Masoud, K., Naser, V. & Soleiman, A. (2003) Effect of fortified flour with ferrous sulfate alone and with Na2EDTA on iron deficiency anemia and serum zinc. Food Agric. Environ. 3:69-71.
16. Davidsson, L., Kastenmayer, P. & Hurrell, R. F. (1994) Sodium iron EDTA [NaFe(III)EDTA] as a food fortificant: the effect on the absorption and retention of zinc and calcium in women. Am. J. Clin. Nutr. 60:231-237.
17. Herman, S., Griffin, I. J., Suwati, S., Ernawati, F., Permaesih, D., Pambudi, D. & Abrams, S. (2002) Co-fortification of iron fortified flour with zinc sulfate but not zinc oxide, decreases iron absorption in Indonesian children. Am. J. Clin. Nutr. 76:813-817.
18. Association of Official Analytical Chemists (1995) Official Method of Analysis 16th ed. 1995 AOAC Washington, DC.
19. Abrams, S. A. (1999) Using stable isotopes to assess the mineral absorption and utilization by children. Am. J. Clin. Nutr. 70:955-964.
20. Abrams, S. A., Griffin, I. J. & Herman, S. (2002) Using stable isotopes to assess the bioavailability of minerals in food fortification programs. Food Nutr. Bull. 23:158-165.[Medline]
21. Sari, M., de Pee, S., Martini, E., Herman, S., Sugiatmi, , Bloem, W. M. & Yip, R. (2001) Estimating the prevalence of anemia: a comparison of three methods. Bull. WHO 79:506-511.[Medline]
22. Anonymous (1998) Tumor marker assay protocols 1998 Ferritin-IRMA. NETRIA, The Royal Hospitals NHS Trust St. Bartholomew’s Hospital, London, UK.
23. Dualcount () Solid phase no boil assay [Online] Diagnostic Products Corporation http://www.dpcweb.com/package_inserts/ria/pdfs/anemia/kdsp-2.pdf [accessed July 10, 2003].
24. Determination of lithium, zinc and copper in blood serum by flame micro sampling [Online] August 1981 Varian Instrument at work, Number AA –11 http://www.varianinc.com/image/vimage/docs/products/spectr/aa/atworks/aa016.pdf [accessed July 20, 2003].
25. World Health Organization (1978) A Growth Chart for International Use in Maternal and Child Health Care 1978 WHO Geneva, Switzerland.
26. Institute of Medicine (2001) Iron. Dietary Reference Intake 2001:290-393 National Academy Press Washington, DC.
27. Institute of Medicine (2001) Zinc. Dietary Reference Intake 2001:442-501 National Academy Press Washington, DC.
28. Davidsson, L., Dimitriou, T., Boy, E., Walczyk, T. & Hurrell, R. F. (2002) Iron bioavailability from iron-fortified Guatemalan meals based on corn tortillas and black bean paste. Am. J. Clin. Nutr. 75:535-539.
29. Mendoza, C., Viteri, F. E., Lönnerdal, B., Raboy, V., Young, K. A. & Brown, K. H. (2001) Absorption of iron from unmodified maize and genetically altered, low-phytate maize fortified with ferrous sulfate or sodium iron EDTA. Am. J. Clin. Nutr. 73:80-85.
30. Davidsson, L., Almgren, A., Sandstrom, B. & Hurrell, R. F. (1995) Zinc absorption in adult humans: the effect of iron fortification. Br. J. Nutr. 75:417-425.
31. Fairweather-Tait, S. J., Wharf, S. G. & Fox, T. E. (1995) Zinc absorption in infants fed iron-fortified weaning food. Am. J. Clin. Nutr. 62(4):785-789.
32. Crofton, R. W., Gvozdanovic, D., Gvozdanovic, S., Khin, C. C., Brunt, P. W., Mowat, N. A. & Aggett, P. J. (1989) Inorganic zinc and the intestinal absorption of ferrous iron. Am. J. Clin. Nutr. 50:141-144.
33. Rossander-Hultén, L., Brune, M., Sandström, B., Lönnerdal, B. & Hallberg, L. (1991) Competitive inhibition of iron absorption by manganese and zinc in humans. Am. J. Clin. Nutr. 54:152-156.
34. Nävert, B., Sandström, B. & Cederblad, A. (1985) Reduction of the phytate content of bran by leavening in bread and its effect on zinc absorption in man. Br. J. Nutr. 53:47-53.[Medline]
35. Larsson, M., Rossander-Hulthen, L., Sandström, B. & Sandberg, A.-S. (1996) Improving zinc and iron absorption from breakfast meals containing malted oats with reduced phytate content. Br. J. Nutr. 76:677-688.[Medline]
36. Hapuarachchi, S., Gooneratne, J. & Kumarapperuma, S. C. (2003) Effect of parboiling on the reduction of phytate in different varieties of rice. Sri Lanka Association for the Advancement of Science. Proceedings of the 59th Annual Session-Part I-604E2 (abs.) .
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