M. Munirul Islam*
International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh
Leslie R. Woodhouse
5 USDA Western Human Nutrition Research Center, Davis, CA
Mohammad Bakhtiar Hossain
International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh
Tahmeed Ahmed
International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh
M. Nazmul Huda
International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh
Tanveer Ahmed
International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh
Janet M. Peerson
Department of Nutrition and Program in International and Community Nutrition, University of California, Davis, Davis, CA
Christine Hotz
HarvestPlus, International Food Policy Research Institute, Washington, DC
Kenneth H. Brown
Department of Nutrition and Program in International and Community Nutrition, University of California, Davis, Davis, CA
Total Zinc Absorption, Conventional Rice, Higher-Zinc Rice, Bangladeshi Preschool Children
International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh
Quality and Nutrition
Study design. The study was designed to permit within-child comparisons of zinc absorption from mixed diets containing either HZnR or CR, with or without added zinc, by using the dual stable-isotope tracer ratio technique (11,12). Two groups of children were studied. In the first group of 22 children (14 boys, 8 girls; study group A), HZnR was compared with CR and no added zinc; in the second group of 20 children (7 boys, 13 girls; study group B), HZnR was compared with CR+Zn, such that the total daily zinc intake was planned to match the total amount of zinc provided in the HZnR diet. However, as indicated below, we were not successful in matching the zinc intakes for the study group B comparisons for several reasons. Nevertheless, the latter results are still being presented because they provide useful information on zinc absorption by young children receiving different intakes of zinc. The research protocol was approved by the Research and Ethical Review Committee of the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B) and the Institutional Review Board of the University of California, Davis. Study site and participants. The study was conducted at the research ward of the ICDDR,B in Dhaka, Bangladesh. The study participants were non–breast-fed children 36–59 mo of age who were recruited from a low-income, periurban community near Dhaka. The study inclusion criteria were as follows: weight-for-height and height-for-age Z-score > 22 with respect to the WHO growth standard (5) and absence of any current illnesses or episodes of diarrhea within the previous 14 d or consumption of zinc supplements during this same period of time. Field workers visited individual homes in the participating community to inquire about the presence of a child in the appropriate age range and to explore parental willingness to enroll the child in the study. Interested families were then invited to attend a screening session in the community, where a study physician verified the childs age, using a birth certificate or immunization card, assessed the childs weight and height, and completed a medical history and physical examination. Height was measured by using a locally made measuring board with 0.1-cm divisions, and weight was measured by using an electronic balance sensitive to 2 g (Seca model no. 7281321009). Eligible children were then requested to attend the research ward if their parents provided written, informed consent. Children who had not received any antihelminthic medications in the previous 3 mo were given a single dose of albendazole (400 mg) to treat possible helminth infections, and they were then scheduled to report to the research ward 2 wk later. Study protocol and interventions. The study participants were admitted to the research ward in groups of #4 children for a period of 4 d each. All children received fixed amounts of the study diet, including either HZnR or CR, for all 3 meals on all study days. On study day 1 the children were admitted to the research ward, and they received the CR diet while becoming accustomed to their new surroundings and study procedures. On the following day (study day 2), a random selection of half the children in study group A received the diet prepared with HZnR, and on the next day (study day 3) they received the diet prepared with CR; the other half of the children in study group A received the same 2 diets in the reverse order. Half of the children in study group B received the diet containing HZnR on study day 2 and the CR+Zn diet on study day 3; the remaining children in study group B received these diets in reverse order. On study day 4 the children were discharged from the research ward. Study diets. The study diets were composed of 3 main dishes: cooked rice, lentil soup, and fried green papaya. The children were also allowed to eat bananas (a low-zinc food) ad libitum if they requested additional food between meals, which usually occurred only at night. Individual servings of each dish were prepared separately for each child and served in equally divided portions at breakfast (0800–0900), lunch (1230– 1330), and dinner (1800–1900). The variety of HZnR used for the study was locally grown IR-68144, which was provided by the Bangladesh Rice Research Institute, parboiled, dried, hulled using a modified Satake dehuller (THU-35A), and milled for 30 s in a Grainman mill (no. 60; Grain Machinery Manufacturing Corporation). The variety of CR fed to the children was locally grown BR-28, which was parboiled, dried, hulled, and milled for 50 s using the same type of milling device. According to the laboratory analyses completed before the start of the study, the milled, unwashed IR-68144 rice (HZnR) contained 2.60 mg zinc and 771 mg phytate per 100 g dry weight, and the BR-28 rice (CR) contained 1.35 mg zinc and 544 mg phytate per 100 g dry weight. Thus, we anticipated that children would receive ;1.88 mg more zinc per day from 150 g of HZnR than from 150 g of the CR. Laboratory methods for rice zinc and phytate analyses are described elsewhere. Before cooking, 150 g of the parboiled, milled rice was washed briefly 3 times in ;450 mL of locally purchased purified water containing a negligible amount of zinc (;2–3 ppb) each time. The wash water was discarded after each washing, and the rice was then cooked in another ;450 mL of water for ;30 min in an automatic Teflon-coated electric rice cooker (RCS200-CN; Rival) until all water was absorbed. Experiments conducted before initiation of the study showed that the cooker was not a source of zinc contamination.
J. Nutr. 143: 519–525, 2013.
Journal