| Nutritional Status Has Marginal Influence on the Metabolism of Inorganic Arsenic in Pregnant Bangladeshi Women Li Li,1 Eva-Charlotte Ekström,2 Walter Goessler,3 Bo Lönnerdal,4 Barbro Nermell,1 Mohammad Yunus,5 Anisur Rahman,2,5 Shams El Arifeen,5 Lars Åke Persson,2 and Marie Vahter1 1Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden; 2International Maternal and Child Health, Uppsala University, Uppsala, Sweden; 3Institute of Chemistry - Analytical Chemistry, Karl-Franzens University, Graz, Austria; 4Department of Nutrition, University of California-Davis, Davis, California, USA; 5ICDDR,B (International Centre for Diarrhoeal Disease Research, Bangladesh), Centre for Health and Population Research, Dhaka, Bangladesh Abstract
Background: The interindividual variation in metabolism of inorganic arsenic (iAs) , involving methylation via one-carbon metabolism, has been well documented, but the reasons remain unclear. Objectives: In this population-based study we aimed to elucidate the effect of nutrition on As methylation among women in Matlab, Bangladesh, where people are chronically exposed to iAs via drinking water. Methods: We studied effects of macronutrient status using body mass index (BMI) among 442 women in early pregnancy (gestational week 8) , and effects of micronutrient status (plasma folate, vitamin B12, zinc, ferritin, and selenium) among 753 women at gestational week 14. Arsenic metabolites in urine were measured by HPLC combined with hydride generation inductively coupled plasma mass spectrometry. Results: The median concentration of As in urine was 97 µg/L (range, 5–1,216 µg/L, adjusted by specific gravity) . The average proportions of iAs, monomethylarsonic acid, and dimethylarsinic acid in urine in gestational week 8 were 15%, 11%, and 74%, respectively. Thus, the women had efficient As methylation in spite of being poorly nourished (one-third had BMIs < 18.5 kg/m2) and having elevated As exposure, both of which are known to decrease As methylation. The metabolism of iAs was only marginally influenced by micronutrient status, probably because women, especially in pregnancy and with low folate intake, have an efficient betaine-mediated remethylation of homocysteine, which is essential for an efficient As methylation. Conclusions: In spite of the high As exposure and prevalent malnutrition, overall As methylation in women in early pregnancy was remarkably efficient. The As exposure level had the greatest impact on As methylation among the studied factors. Key words: arsenic, metabolite, methylation, nutrition, pregnant women, urine. Environ Health Perspect 116:315–321 (2008) . doi:10.1289/ehp.10639 available via http://dx.doi.org/ [Online 19 November 2007]
Address correspondence to M. Vahter, Institute of Environmental Medicine, Karolinska Institutet, P.O. Box 210, Nobels väg 13, SE 17177 Stockholm, Sweden. Telephone: 46 8 524 87540. Fax: 46 8 33 70 39. E-mail: marie.vahter@ki.se We thank the field workers for collecting and handling all samples and information. The original MINIMat (Maternal and Infant Nutrition Interventions of Matlab) supplementation study was supported by the Swedish International Development Agency (Sida) , the World Health Organization, and USAID. The arsenic study was supported by Sida (SWE-2002-067) ; the Swedish Research Council (K2004-27X-14992-01A) ; the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (21.0/2003-1100) ; and the Karolinska Institutet. The authors declare they have no competing financial interests. Received 6 July 2007 ; accepted 15 November 2007.
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