The study, led by Mary Gamble from Columbia University Mailman School of Public Health, indicates that folic acid supplements may offer a means to reduce toxicity associated with arsenic exposure from drinking water - a significant public health problem in at least 70 countries, including several developing countries and parts of the U.S.
"Although additional studies are needed, the results of this study suggest that a simple, low-cost nutritional intervention may help to prevent some of the long-term health consequences associated with arsenic exposure for the many populations at risk," said Gamble.
Folate is found in foods such as green leafy vegetables, chick peas and lentils, and an overwhelming body of evidence links has linked folate deficiency in early pregnancy to increased risk of neural tube defects (NTD) - most commonly spina bifida and anencephaly - in infants.
This connection led to the 1998 introduction of public health measures in the US and Canada, where all grain products are fortified with folic acid - the synthetic, bioavailable form of folate.
While preliminary evidence indicates that the measure is having an effect with a reported 15 to 50 per cent reduction in NTD incidence, parallel measures in European countries, including the UK and Ireland, are still on the table.
The new randomised, double-blind, placebo-controlled study, published in the October issue of the American Journal of Clinical Nutrition , followed 130 arsenic-exposed Bangladeshi adults, and supplemented them with folic acid (400 micrograms per day) or placebo for 12 weeks.
The participants had low blood folate levels at the start of the study.
The researchers hypothesised that folic acid supplementation would increase arsenic elimination by methylating ingested inorganic arsenic (InAs) to monomethylarsonic (MMAs) and dimethylarsinic (DMAs) acids, which can be easily excreted via the urine.
After 12 weeks of supplementation, Gamble and co-workers found that MMAs in blood was reduced by a mean 22 per cent in the folic acid supplementation group, compared to 1.2 per cent in the placebe group.
No change in blood DMAs levels were observed, but increased urinary DMAs were recorded in the folic acid supplemented individuals.
The researchers report that, as a result of folic acid supplementation total blood arsenic levels were reduced by 13.6 per cent, and by 2.5 per cent in the placebo group.
"Folic acid supplementation enhanced the detoxification of arsenic to a form that is more readily excreted in urine," said Gamble.
"Clearly the first priority should focus on mitigation efforts to lower arsenic exposure.
But this very exciting and significant finding implies that folic acid has therapeutic potential for people who have been exposed to arsenic," she added.
Commenting on the research, Claudia Thompson, acting director of the federally funded Superfund Basic Research Program (SPRB), said: "The work that our grantees are doing in Bangladesh is extraordinary.
Not only is the research they are conducting improving the quality of life for the people in Bangladesh, but it can potentially help the more than 100 million people worldwide that are chronically exposed to arsenic." Source: American Journal of Clinical Nutrition October 2007, Volume 86, Pages 1202-1209 "Folic Acid Supplementation Lowers Blood Arsenic" Authors: M.V Gamble, X. Liu, V. Slavkovich, J.R. Pilsner, V. Ilievski, P. Factor-Litvak, D. Levy, S. Alam, M. Islam, F. Parvez, H. Ahsan and J.H. Graziano