Folate and arsenic metabolism: a double-blind, placebo-controlled folic acid–supplementation trial in Bangladesh

Background Populations in South and East Asia and many other regions of the world are chronically exposed to arsenic-contaminated drinking water. To various degrees, ingested inorganic arsenic (InAs) is methylated to monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) via folate-dependent one-carbon metabolism; impaired methylation is associated with adverse health outcomes. Consequently, folate nutritional status may influence arsenic methylation and toxicity. Objective The objective of this study was to test the hypothesis that folic acid supplementation of arsenic-exposed adults would increase arsenic methylation. Design Two hundred adults in a rural region of Bangladesh, previously found to have low plasma concentrations of folate ( Results The increase in the proportion of total urinary arsenic excreted as DMA in the folic acid group…