A study of those with private ground water wells as their household water sources reveals that what they eat may affect how much arsenic they absorb.
Millions of people worldwide are exposed
to arsenic from contaminated water, and we all are exposed to arsenic via the
food we eat. New research published in BioMed Central's open access journalNutrition Journalhas demonstrated that people who ate more
dietary vitamin B12 and animal protein had lower levels of arsenic (measured by
deposition in toenails). Total dietary fat, animal fat, vegetable fat and
saturated fat all were also associated with lower levels of arsenic, while
omega 3 fatty acids, such as those found in fish oil, were associated with
Long-term exposure to high levels of
arsenic is known to cause skin lesions, cancer and cardiovascular disease, and
also affects fetal development. Even low concentrations of arsenic are
potentially dangerous. Arsenic is found in some water supplies, but more people
are exposed via their diet. Staples such as rice contain arsenic, especially
the toxic inorganic forms, while fish, although high in total arsenic, contains
organic forms that are thought to be less toxic.
Inside the body arsenic is methylated to
aid excretion in urine, but arsenic also has an affinity for keratin, and can
be deposited in hair and nails as they grow. Consequently, levels of arsenic
preserved in nails or hair can be used as a biomarker for arsenic exposure over
periods of months to years.
Researchers from Dartmouth College and
the Geisel School of Medicine at Dartmouth looked at the levels of arsenic in
toenails of residents of New Hampshire who all use private ground water wells
as their household water source.
Results of the study showed that arsenic
in nails was positively associated with both alcohol and omega 3 fatty acids,
however, lower levels of arsenic were found for people who ate greater amounts
of vegetable and animal fat. Prof. Kathy Cottingham, who directed the study,
explains, "While there may be a direct interaction between fats and
arsenic preventing absorption or binding to keratin in nails, the results may
simply reflect dietary preference, with people who eat a diet rich in fats not
eating foods high in arsenic, such as rice."
Joann Gruber, who led the study, notes,
"Humans can be very efficient at removing arsenic from the body. Improved
methylation reduces the amount of inorganic arsenic circulating in the body.
Surprisingly, we didn't see a reduction in toenail arsenic with other dietary
factors known to be necessary for arsenic methylation, such as folic acid. This
may be because the population we sampled had adequate amounts of these factors
in their diet."
The authors currently are working on
similar studies in children, through the Children's Environmental Health and
Disease Prevention Center at Dartmouth.