|Folic Acid Lowers Blood Arsenic Levels in Bangladesh
A new study conducted in Bangladesh finds that folic acid supplements
can dramatically lower blood arsenic levels in individuals chronically
exposed to arsenic-contaminated drinking water. Arsenic is a toxic
element that is naturally present in some soils and water. Arsenic-contaminated
drinking water is currently a significant public health problem
in at least 70 countries, including several developing countries
and also parts of the United States. 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 was funded by the National Institute of Environmental
Health Sciences (NIEHS) at the National Institutes of Health (NIH).
Researchers found that treatment with 400 micrograms a day of
folic acid, the U.S. Recommended Dietary Allowance, reduced total
blood arsenic levels in a Bangladesh study population by 14 percent.
Folate is a B vitamin found in leafy vegetables, citrus fruits,
beans, and whole grains. Folic acid can also be taken as a vitamin
supplement, and in the United States, it is added to flour and
other fortified foods. The researchers found that folate deficiency
is very common in Bangladesh, where the study was conducted, but
is not as problematic in the United States due to folate fortification.
Additional studies are needed to determine if folic acid similarly
lowers blood arsenic in populations where folate deficiency is
less common, such as in the United States.
William Suk, Ph.D., Acting Deputy Director of the NIEHS discussed
the significance of this work in Bangladesh to the U.S. He explains
that arsenic contamination of groundwater is one of the five most
common inorganic compounds found at Superfund sites and is present
at over 70 percent of the sites. "Because of the prevalence
of arsenic, the SBRP has placed an emphasis on supporting arsenic-related
research in heavily affected areas all over the world to understand
and mitigate the health issues arising from arsenic exposure via
drinking water. This research is already demonstrating its relevance
to exposures that are occurring in the United States."
"Clearly the first priority should focus on mitigation efforts
to lower arsenic exposure. But this is a very exciting and significant
finding, and implies that folic acid has therapeutic potential
for people who have been exposed to arsenic." said Mary Gamble,
Ph.D., a researcher at Columbia University and the lead author
on the study that was funded by the NIEHS. "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."
"Folic acid supplementation enhanced the detoxification of
arsenic to a form that is more readily excreted in urine," said
Gamble. The study results are published in the October issue of
the American Journal of Clinical Nutrition. The study
is jointly supported through NIEHS and the Superfund Basic Research
Gamble explains how this detoxification process is able to lower
the levels of arsenic found in the blood. She explains how the
folic acid increased the methylation or detoxification of arsenic
in the body, allowing the body to change some of the more toxic
metabolite, or methylarsonic (MMA) acid, to a form that could more
easily be excreted from the body.
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 US Environmental
Protection Agency (EPA) guidelines, which set a limit of 10 micrograms
per liter for arsenic in drinking water.
The initial supplement study included 200 folate-deficient participants
drawn from a larger cohort study in Bangladesh examining the adverse
health effects of arsenic. Study participants received either a
daily tablet of 400 micrograms per day of folic acid or a placebo
for twelve weeks. The researchers collected blood and urine samples
at the beginning and end of the study. Dr. Gamble pointed out that, "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,
Ph.D., a co-author on the study.
"The work that our grantees are doing in Bangladesh is extraordinary," said
Claudia Thompson, Ph.D., acting director of the SBRP. "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."
The authors also stress that the study results imply that folic
acid supplementation may help to reduce body stores of arsenic
even after exposure has been eliminated. Elevated risk for adverse
health outcomes persists for decades after exposure has ceased.
Additional studies are needed, the researchers add, including,
for example, studies to determine the optimal dose and duration
of treatment, and studies that include health outcomes.
The National Institute of Environmental Health Sciences (NIEHS),
a component of the National Institutes of Health, supports research
to understand the effects of the environment on human health. For
more information on environmental health topics, please visit our
website at http://www.niehs.nih.gov/.
Superfund Basic Research Program (SBRP) is a network of university
grants that are designed to seek solutions to the complex health
and environmental issues associated with the nation's hazardous
waste sites. The research conducted by the SBRP is a coordinated
effort with the Environmental Protection Agency, which is the federal
entity charged with cleaning up the worst hazardous waste sites
in the country. The SBRP is federally funded and administered by
the National Institute of Environmental Health Sciences, an institute
of the National Institutes of Health. http://www.niehs.nih.gov/research/supported/sbrp/index.cfm.
The SPRP will hold its 20th anniversary annual meeting, "20
Years of Success and a Vision for the Future," in Durham,
North Carolina, December 3-5, 2007. Visit http://tools.niehs.nih.gov/sbrp/events/index.cfm?id=23 for
The National Institutes of Health (NIH) — The Nation's
Medical Research Agency — includes 27 Institutes and
Centers and is a component of the U.S. Department of Health and
Human Services. It is the primary federal agency for conducting
and supporting basic, clinical and translational medical research,
and it investigates the causes, treatments, and cures for both
common and rare diseases. For more information about NIH and
its programs, visit www.nih.gov.