ATA members raise concern about reduction in dietary iodine intake

Following publication of an article in the February 18 issue of the New England Journal of Medicine (Vol. 362 No. 7 pp 590-599) by Bibbins-Domingo, et al. that projected the effect of moderate dietary salt reductions on future cardiac disease rates, several members of the American Thyroid Association, concerned about the subsequent potential reduction in availability of iodine, have responded with a letter in the current issue of the NEJM (Vol. 362 No. 23 pp 2224-2226).

"Iodized salt is an important source of dietary iodine in the U.S. and worldwide," wrote ATA members Elizabeth N. Pearce, MD, Boston University Medical Center, Offie P. Soldin, PhD, MBA, Georgetown University Medical Center and Alex Stagnaro-Green, MD, currently at George Washington University (prior affiliation: Touro University College of Medicine). "Iodine, essential for the synthesis of thyroid hormones, is obtained solely through diet."

To prevent thyroid conditions, such as goiter and neonatal iodine deficiency, and provide adequate amounts of iodine in the diet, iodized salt has been sold to consumers through U.S. supermarkets since the 1920s.

In their letter to the NEJM, Pearce, Soldin and Stagnaro-Green noted that iodine levels in the U.S. have decreased by 50 percent over the past three decades. Although the overall population in the U.S. still receives sufficient iodine, studies suggest that many pregnant women may be iodine deficient and, since iodine requirements increase by 50 to 100 percent during pregnancy, they recommended that decreased salt consumption must take into account the need for iodine sufficiency, especially among pregnant women and infants. While iodine is essential for proper thyroid hormone synthesis, thyroid hormones are critical to normal infant brain development and preventing fetal neurodevelopmental and neurobehavioral deficits.

"We agree with the call for decreased salt consumption for better cardiac health," wrote Soldin, Pearce and Stagnaro-Green. "However, we recommend that all producers of commercially prepared foods - accounting for up to 70 percent of all salt consumed in the U.S. - use iodized salt, a step not currently practiced by commercial foods manufacturers. Any decrease in salt intake should not cause a reduction in dietary iodine intake."

The American Thyroid Association officially recommends that women receive 150 µg iodine supplements daily during pregnancy and lactation and that all prenatal vitamin/mineral preparations contain 150 µg of iodine. The published recommendation can be found at the ATA http://www.thyroid.org/professionals/education/pregnancy.html.

The letter submitted by ATA members to the New England Journal of Medicine may be found on-line at: http://content.nejm.org/cgi/content/short/362/23/2224