Background

In some epidemiological studies, a positive association of body mass index (BMI) with inorganic arsenic (iAs) metabolism parameters (percentage dimethylarsinic acid [%DMA] and secondary methylation index [SMI]) has been found. In iAs metabolism, S-Adenosyl methionine is converted to S-Adenosyl homocysteine. Sedentarism has been associated with a higher risk of hyperhomocysteinemia. Physical activity has shown an inconsistent negative association with BMI. Therefore, our objective was to evaluate whether physical activity is associated to iAs metabolism independently of BMI.

Methods

We performed a cross-sectional secondary analysis on 800 non-diabetic women, ≥18 years, who participated as population controls in a previous study on breast cancer in northern Mexico. Participants were interviewed about physical activity during their lifetime, and their weight and size were obtained. Urinary arsenic metabolites concentrations were determined by high performance liquid chromatography coupled with mass spectrometry.

Results

In the study population, total arsenic ranged from 0.71 to 303.29 μg/L, and the lifetime average physical activity from 0 to 788.40 min/week. BMI was significantly and negatively associated with percentage monomethylarsonic acid (%MMA) and primary methylation index (PMI), and positively associated with %DMA, SMI and TMI, respectively. Likewise, physical activity was negatively associated with %iAs and %MMA, and positively associated with %DMA, SMI and TMI. These results remained after BMI was adjusted for physical activity and viceversa.

Conclusion

This study confirms the relationship between BMI and iAs metabolism parameters and provides new evidence on the association between physical activity and iAs metabolism.

中文翻译：

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墨西哥女性的体力活动、体重指数和砷代谢

背景

在一些流行病学研究中，发现体重指数 (BMI) 与无机砷 (iAs) 代谢参数（二甲基胂酸百分比 [%DMA] 和次级甲基化指数 [SMI]）呈正相关。在 iAs 代谢中，S-腺苷甲硫氨酸转化为 S-腺苷高半胱氨酸。久坐与高同型半胱氨酸血症的风险较高有关。体力活动与 BMI 呈不一致的负相关关系。因此，我们的目标是评估体力活动是否与 BMI 无关的 iAs 代谢相关。

方法

我们对 800 名 18 岁以上的非糖尿病女性进行了横断面二次分析，她们作为人群对照参加了墨西哥北部的一项乳腺癌研究。采访参与者一生中的身体活动情况，并获得他们的体重和体型。通过高效液相色谱结合质谱法测定尿砷代谢物浓度。

结果

在研究人群中，总砷含量范围为0.71至303.29微克/升，终生平均体力活动范围为0至788.40分钟/周。BMI 与单甲基胂酸百分比 (%MMA) 和初级甲基化指数 (PMI) 呈显着负相关，与 %DMA、SMI 和 TMI 呈正相关。同样，体力活动与 %iAs 和 %MMA 呈负相关，与 %DMA、SMI 和 TMI 呈正相关。根据体力活动调整体重指数后，这些结果仍然存在，反之亦然。

结论

这项研究证实了BMI与iAs代谢参数之间的关系，并为体力活动与iAs代谢之间的关联提供了新证据。