28679
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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 ( < /=9 nmol/L ) were enrolled in a randomized , double-blind , placebo-controlled folic acid-supplementation trial . Plasma concentrations of folate and homocysteine and urinary concentrations of arsenic metabolites were analyzed at baseline and after 12 wk of supplementation with folic acid at a dose of 400 microg/d or placebo . RESULTS The increase in the proportion of total urinary arsenic excreted as DMA in the folic acid group ( 72 % before and 79 % after supplementation ) was significantly ( P < 0.0001 ) greater than that in the placebo group , as was the reduction in the proportions of total urinary arsenic excreted as MMA ( 13 % and 10 % , respectively ; P < 0.0001 ) and as InAs ( 15 % and 11 % , respectively ; P < 0.001 ) . CONCLUSIONS These data indicate that folic acid supplementation to participants with low plasma folate enhances arsenic methylation . Because persons whose urine contains low proportions of DMA and high proportions of MMA and InAs have been reported to be at greater risk of skin and bladder cancers and peripheral vascular disease , these results suggest that folic acid supplementation may reduce the risk of arsenic-related health outcomes .
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Intervention_Control
placebo-controlled
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Intervention_Pharmacological
folic acid-supplementation
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Intervention_Pharmacological
folic acid supplementation
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Intervention_Control
placebo-controlled
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Intervention_Pharmacological
folic acid-supplementation
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Intervention_Pharmacological
supplementation with folic acid
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Intervention_Control
placebo
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Intervention_Control
placebo
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Intervention_Pharmacological
folic acid
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Intervention_Pharmacological
folic acid
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Outcome_Physical
arsenic methylation
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Outcome_Physical
Plasma concentrations of folate and homocysteine and urinary concentrations of arsenic metabolites
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Outcome_Physical
proportion of total urinary arsenic
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Outcome_Physical
total urinary arsenic excreted
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Participant_Condition
chronically exposed to arsenic-contaminated drinking water
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Participant_Sample-size
Two hundred
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Participant_Age
adults
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Participant_Condition
low plasma concentrations of folate ( < /=9 nmol/L )
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Participant_Condition
low plasma folate