A new study by researchers at Columbia University Mailman School of Public Health finds that folic acid supplements can dramatically lower blood arsenic levels in individuals exposed to arsenic through contaminated drinking water.
This toxic element, naturally present in some aquifers used for drinking, is currently a significant public health problem in at least 70 countries, including several developing countries and also parts of the U.S. Chronic arsenic exposure is associated with increased risk for skin, liver and bladder cancers, skin lesions, cardiovascular disease, and other adverse health outcomes. The study results are published in the October issue of the American Journal of Clinical Nutrition.
The researchers found that treatment with 400 micrograms a day of folic acid, the U.S. recommended dietary allowance, reduced total blood arsenic levels in the study population by 14 percent. Folate, a B vitamin found in leafy vegetables, citrus fruits, beans, and whole grains, can also be taken as a vitamin supplement, and in the U.S., is added to flour and other fortified foods. The researchers found that folate deficiency is very common in Bangladesh, where the study was conducted.
“Folic acid supplementation enhanced the detoxification of arsenic to a form that is more readily excreted in urine,” said Mary Gamble, PhD, assistant professor of Environmental Health Sciences at the Mailman School, and lead author. The study is jointly supported by the National Institute of Environmental Health Sciences, part of the National Institutes of Health and the federally funded Superfund Basic Research Program (SPRB), which seeks solutions to the complex health and environmental issues associated with the nation's hazardous waste sites.
Folic acid increased the methylation or detoxification of arsenic in the body, allowing the body to change some of its more toxic metabolite, or methylarsonic (MMA) acid, to a form that could more easily be excreted from the body, thus lowering the levels of arsenic found in the blood.
Chronic arsenic exposure currently affects 100 million persons worldwide, including populations in Bangladesh. The arsenic levels in drinking water in some parts of Bangladesh reach as high as 100 times the World Health Organization and the U.S. Environmental Protection Agency (EPA) guidelines, which set a limit of 10 micrograms per liter for arsenic in drinking water.
The initial intervention study included 200 folate-deficient participants drawn from a larger cohort study in Bangladesh examining the adverse health effects of arsenic. Dr. Gamble pointed out, “The technology to measure arsenic in blood, and particularly to measure the individual arsenic metabolites in blood, didn't exist when the studies were first planned.” She credits the advanced technology to recent advances in other laboratories at Columbia, including work conducted by Superfund grantee Joseph H. Graziano, PhD, professor of Environmental Health Sciences at the Mailman School, and a co-author on the study.