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Shaky Amount of Iodine in U.S. Salt

Some ‘Iodine-Fortified’ Table Salt Falls Short of Recommended Levels of the Nutrient, Study Shows

Author: Salynn Boyles

Feb. 1, 2008 — There are fewer food sources of iodine in the American diet 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 “iodine activist.”

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 Arlington.

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 says.

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.

Dasgupta, P.K., Environmental Science and Technology, Feb. 15, 2008; online edition.
Purnendu K. Dasgupta, PhD, professor and chairman, department of chemistry, The University of Texas at Arlington.
Elizabeth N. Pearce, MD, assistant professor of medicine, Boston University School of Medicine.
Journal of Clinical Endocrinology and Metabolism, 2004.