Intakes of Dairy Products and Dietary Supplements Are Positively Associated with Iodine Status among US Children

Although pregnant women and some groups of reproductive-age women in the US may be at risk of iodine deficiency, data also suggest that iodine intake among many U.S. children may be above requirements. Our objective was to describe the association of iodine sources with iodine status among children. We analyzed 2007-2010 NHANES data of urine iodine concentration (UIC) spot tests for children aged 6-12 y (n = 1553) and used WHO criteria for iodine status (median UIC: 100-199 mu g/L = adequate; 200-299 mu g/L = above requirements; >= 300 mu g/L = excess). The overall median UIC was above requirements for children aged 6-12 y [211 mu g/L (95% Cl: 194, 228 mu g/ L)]. Median UIC increased by quartile of previous day dairy intake, ranging from adequate in the lowest quartile [157 mu g/L (95% Cl: 141, 170 mu g/L)] to above requirements in the highest quartile [278 mu g/L (95% Cl: 252, 336 mu g/L)]. Median UIC was 303 mu g/L (95% Cl: 238, 345 mu g/L) among the 17% of children who had taken a dietary supplement containing iodine the previous day, compared with 198 mu g/L (95% Cl: 182, 214 mu g/L) among those who had not. In adjusted regression analyses, recent dairy intake and recent supplement use were significantly positively associated with UIC levels, whereas recent grain intake was negatively associated. Adding salt to food at the table was not associated with UIC. Iodine-containing supplements are likely not needed by most schoolchildren in the US because dietary iodine intake is adequate in this age group.