Abstract P359: Assessment of Household Salt Types, Iodine Intake, and Iodine Status in 2019-2020 NHANES

Background: Iodine is an essential nutrient required for normal thyroid function in all age groups as well as healthy fetal, infant, and child development and growth. Because iodine levels in most foods are low, iodine usually must be provided through dietary supplements or fortified foods (such as salt). In recent NHANES cycles, sub-optimal iodine status has been observed in some U.S. populations, most notably pregnant women. Recent health campaigns have emphasized consuming less sodium and have focused on the primary source of the excess sodium in the U.S. diet: commercially prepared foods, most of which are made with non-iodized salt. Also, recent secular trends towards less home cooking and more use of non-iodized table salts may be contributing to relatively low usage of iodized salt, which was estimated in 2014 to comprise only half of retail salt sales. Therefore, for individuals who also limit their home use of salt in food preparation or at the table, an unintended consequence may be a decline in iodine intake. Population-level data thus are needed on the relative contributions of various foods to iodine intake in relation to iodine status markers, to characterize population groups at risk and develop guidance on appropriate dietary and supplementation strategies. Objective: Describe new measures of iodine intake and iodine status added into NHANES 2019-20, which is a nationally representative survey of the U.S. population. Methods: Iodine intake is being assessed through a questionnaire about household salt types (such as iodized salt or sea salt) and measured iodine content of household iodized salt, as well as individual 24-hour dietary recalls and use of iodine containing dietary supplements. This will be the first time NHANES will estimate dietary iodine intake using a newly developed USDA Special Interest Database on Iodine Content of Foods. Biomarkers include a thyroid panel (including thyroglobulin), inhibitors of iodine uptake in the thyroid (e.g., perchlorates), and urinary iodine concentration. Conclusions: The upcoming NHANES cycle will yield novel data on U.S. population coverage of household iodized salt, as well as individual thyroid and iodine status in relation to dietary iodine intake. Groups at risk from increased physiologic need or dietary preferences that limit iodine sources will be identified. A key tool in undertaking this work will be a new food composition database on the iodine content of U.S. foods. Clarification of key sources of iodine in the U.S. diet will be important in developing dietary guidance.