Folic acid supplementation lowers blood arsenic.
BACKGROUND
Chronic arsenic exposure currently affects >100 million persons worldwide. Methylation of ingested inorganic arsenic (InAs) to monomethylarsonic (MMAs) and dimethylarsinic (DMAs) acids relies on folate-dependent one-carbon metabolism and facilitates urinary arsenic elimination.


OBJECTIVE
We hypothesized that folic acid supplementation to arsenic-exposed Bangladeshi adults would increase arsenic methylation and thereby lower total blood arsenic.


METHODS
In this randomized, double-blind, placebo-controlled trial, we evaluated blood concentrations of total arsenic, InAs, MMAs, and DMAs in 130 participants with low plasma folate (<9 nmol/L) before and after 12 wk of supplementation with folic acid (400 microg/d) or placebo.


RESULTS
MMAs in blood was reduced by a mean +/- SE of 22.24 +/- 2.86% in the folic acid supplementation group and by 1.24 +/- 3.59% in the placebe group (P < 0.0001). There was no change in DMAs in blood; DMAs is rapidly excreted in urine as evidenced by an increase in urinary DMAs (P = 0.0099). Total blood arsenic was reduced by 13.62% in the folic acid supplementation group and by 2.49% in the placebo group (P = 0.0199).


CONCLUSIONS
Folic acid supplementation to participants with low plasma concentrations of folate lowered blood arsenic concentrations, primarily by decreasing blood MMAs and increasing urinary DMAs. Therapeutic strategies to facilitate arsenic methylation, particularly in populations with folate deficiency or hyperhomocysteinemia or both, may lower blood arsenic concentrations and thereby contribute to the prevention of arsenic-induced illnesses.
Gamble
Mary V
MV
Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY 10032, USA. mvg7@columbia.edu
Liu
Xinhua
X
Slavkovich
Vesna
V
Pilsner
J Richard
JR
Ilievski
Vesna
V
Factor-Litvak
Pam
P
Levy
Diane
D
Alam
Shafiul
S
Islam
Mominul
M
Parvez
Faruque
F
Ahsan
Habibul
H
Graziano
Joseph H
JH
D001151:Arsenic / Q000097:blood / Q000378:metabolism* / Q000652:urine; D001152:Arsenicals / Q000378:metabolism / Q000652:urine; D001459:Bangladesh / Q000453:epidemiology; D019587:Dietary Supplements; D004311:Double-Blind Method; D004781:Environmental Exposure / Q000009:adverse effects; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D006710:Homocysteine / Q000097:blood; D006801:Humans; D008297:Male; D008745:Methylation / Q000187:drug effects*; D008875:Middle Aged; D014803:Vitamin B Complex / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D014874:Water Pollutants, Chemical / Q000097:blood / Q000378:metabolism* / Q000652:urine
D001152:Arsenicals; D014874:Water Pollutants, Chemical; D006710:Homocysteine; D014803:Vitamin B Complex; D005492:Folic Acid; C020300:monomethylarsonic acid; D001151:Arsenic