than there were just a few decades ago, raising the risk of iodine deficiency
in a growing number of people. So says a researcher who calls himself an
Even people who buy and use iodine-fortified table salt may be at risk, says
Purnendu K. Dasgupta, PhD, a chemistry professor at the University of Texas at
Dasgupta and colleagues recently tested 88 samples of iodized salt and found
that 47 of them, or 53%, did not meet the U.S. Food and Drug Administration's
recommendations for iodine levels.
Iodine levels tended to decrease in individual containers with exposure to
humidity, but light and heat had little effect.
The findings are published in the latest online issue of the American
Chemical Society journal Environmental Science and Technology.
"We certainly are not saying that people need to eat more salt,"
Dasgupta says. "But if we had mandatory iodization of all salt used in
food, that would solve the problem."
Most Salt Has No Iodine
Iodized salt is now the main source of iodine in the American diet, but only
about 20% of the salt Americans eat contains the micronutrient, Dasgupta
Increasing popular "designer" table salts, such as sea salts and
Kosher salts, usually do not have iodine, and neither does salt used in most
fast foods and processed foods.
Add to this the fact that iodine is no longer used in the production of
commercial breads and dairy products, plus the ever-present public health
warnings about restricting dietary salt, and iodine deficiency becomes a real
threat for some people in the United States, Dasgupta says.
Though government nutrition surveys suggest that iodine deficiency is not a
problem in the United States at the population level, Dasgupta says this may
not be the case for the most vulnerable subgroups: pregnant and nursing women,
babies, and young children.
Iodine is important in the production of thyroid hormones and critical to normal brain
development in newborn infants and children. Iodine deficiency is the leading
preventable cause of cretinism in the developing world. And at least one study
suggests that children in developed countries born to iodine-deficient moms may
have an increased risk of attention deficit hyperactivity disorder (ADHD ).
Pregnant Women Need Iodine
Boston University Medical Center endocrinologist Elizabeth Pearce, MD, tells
WebMD her research suggests that about half of pregnant and nursing women are
not getting enough iodine in their diets .
In her latest study, published last May, sampled breast milk from 47% of
nursing mothers did not contain sufficient iodine to meet their infants'
One problem, she says, is that only about a third of over-the-counter
vitamins recommended for pregnant and nursing women and two-thirds of
vitamins contain iodine.
In 2006, the American Thyroid Association published guidelines recommending
that all pregnant and breastfeeding women take prenatal vitamins containing
iodine, but Pearce says few women have likely heard about the
"It is very difficult to measure iodine deficiency in individuals,"
she says. "Because of this, and because pregnant and breastfeeding women
are particularly vulnerable, these women should make sure that they take a
vitamin with iodine."
By Salynn Boyles
Reviewed by Louise Chang
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