Contributors to iodine status among children in the U.S.

Abstract

While pregnant women and some subgroups of reproductive age women may be at risk for iodine deficiency, data also suggest that iodine intake among children may be above requirements in the U.S. Our objective was to describe the association of iodine sources with iodine status among children. We analyzed 2007–2008 National Health and Nutrition Examination Survey (NHANES) data from urinary iodine (UI) spot tests for children 6–12 y (n=1150), and used WHO criteria for iodine status (median UI 100–199 μg/L=adequate; 200–299 μg/L=above requirements; ≥300μg/L=excess). Overall median UI was above requirements for children 6–12 y (213 μg/L, 95% CI 197–238). Median UI increased by quartile of dairy intake and ranged from adequate in the lowest quartile (156 μg/L, 131–192 μg/L), to above adequate in the highest quartile (293 μg/L, 248–369 μg/L). Median UI was 303 μg/L (253–401 μg/L) among the 15% of children taking a dietary supplement that contained iodine, compared to 205 μg/L (192–221 μg/L) among those not taking a supplement. In regression analyses adjusted for sociodemographic and other dietary factors, recent dairy intake, recent supplement use, and regular table salt use were significantly positively associated with UI levels among children. Public health strategies to reconcile low iodine intakes among pregnant women and above adequate intakes among children will need to consider dairy products, dietary supplements, and salt as important sources of iodine among children.