Department of Pediatrics, College of Medicine, University of Arizona, Tucson, AZ, USA; Mel & Enid Zuckerman College of Public Health, University of Arizona, Tucson, AZ, USA.
Department of Nutritional Sciences, College of Agriculture and Life Sciences, University of Arizona, Tucson, AZ, USA.
Sci Total Environ. 2017 Dec 31;607-608:381-390. doi: 10.1016/j.scitotenv.2017.07.019. Epub 2017 Jul 27.
Exposure to inorganic arsenic (inAs), a potent toxicant, occurs primarily through ingestion of food and water. The efficiency with which it is methylated to mono and dimethyl arsenicals (MMA and DMA) affects toxicity. Folate, vitamins B12 and B6 are required for 1C metabolism, and studies have found that higher levels of these nutrients increase methylation capacity and are associated with protection against adverse health effects from inAs, especially in undernourished populations. Our aim was to determine whether 1C-related nutrients are associated with greater inAs methylation capacity in a general population sample with overall adequate nutrition and low levels of As exposure. Univariate and multivariable regression models were used to evaluate the relationship of dietary and blood nutrients to urinary As methylation in the National Health and Nutrition Examination Survey (NHANES) 2003-2004. Outcome variables were the percent of the sum of inAs and methylated As species (inAs+MMA+DMA) excreted as inAs, MMA, and DMA, and the ratio of MMA:DMA. In univariate models, dietary folate, vitamin B6 and protein intake were associated with lower urinary inAs% and greater DMA% in adults (≥18years), with similar trends in children (6-18). In adjusted models, vitamin B6 intake (p=0.011) and RBC folate (p=0.036) were associated with lower inAs%, while dietary vitamin B12 was associated with higher inAs% (p=0.002) and lower DMA% (p=0.030). Total plasma homocysteine was associated with higher MMA% (p=0.004) and lower DMA% (p=0.003), but not with inAs%; other blood nutrients showed no association with urinary As. Although effect size is small, these findings suggest that 1C nutrients can influence inAs methylation and potentially play an indirect role in reducing toxicity in a general population sample.
接触无机砷（inAs），一种强毒性物质，主要通过摄入食物和水。其被甲基化为单甲基砷酸（MMA）和二甲基砷酸（DMA）的效率影响其毒性。叶酸、维生素 B12 和 B6 是 1C 代谢所必需的，研究发现，这些营养素的水平较高会增加甲基化能力，并与防止无机砷对健康的不利影响有关，尤其是在营养不足的人群中。我们的目的是确定在营养总体充足、砷暴露水平较低的一般人群样本中，与 1C 相关的营养素是否与更高的无机砷甲基化能力有关。单变量和多变量回归模型用于评估膳食和血液营养素与国家健康和营养调查（NHANES）2003-2004 年尿液中砷的甲基化之间的关系。结果变量是总和的百分比的总和无机砷和甲基化砷物种（inAs+MMA+DMA）排泄为无机砷、MMA 和 DMA，以及 MMA：DMA 的比值。在单变量模型中，膳食叶酸、维生素 B6 和蛋白质摄入量与成年人（≥18 岁）尿液中无机砷的百分比较低和 DMA 的百分比较高有关，儿童（6-18 岁）也有类似的趋势。在调整模型中，维生素 B6 摄入量（p=0.011）和 RBC 叶酸（p=0.036）与较低的无机砷百分比有关，而膳食维生素 B12 与较高的无机砷百分比（p=0.002）和较低的 DMA 百分比（p=0.030）有关。总血浆同型半胱氨酸与较高的 MMA 百分比（p=0.004）和较低的 DMA 百分比（p=0.003）有关，但与无机砷无关；其他血液营养素与尿液中砷无关。尽管效应大小较小，但这些发现表明 1C 营养素可以影响无机砷的甲基化，并可能在一般人群样本中发挥间接降低毒性的作用。
