Iodine Intake From Diet and Supplements and Urinary Iodine Concentration in a Cohort of Pregnant Women in the United States

Background: The DRI Estimated Average Requirement (EAR) in pregnancy for Iodine (I), an essential nutrient for fetal neurodevelopment, is 160 & mu;g/d. Supplementation with 150 & mu;g/d I/day is recommended during pregnancy, however, neither dietary intake or the combination of diet and supplement intake has been reported in US pregnant women. Objective: Determine iodine intake from diet and supplements and iodine status in pregnancy by urinary iodine concentration in a large cohort of pregnant women. Design: Pregnant women (n=750) completed the Diet History Questionnaire 2.0 from the National Institute of Cancer or multiple 24-hour recalls at baseline and identified their prenatal supplement(s). Dietary iodine intake was estimated using the USDA, FDA and ODS-NIH Database for the Iodine Content of Common Foods at enrollment, supplemental iodine intake throughout the study using content databases, and urinary iodine concentration (UIC) by the modified Sandell-Kolthoff reaction in samples collected between 14-20 weeks gestation (n=966). Results: The median intake of iodine from diet was 108.8 & mu;g/d, and 63% (473/750) were below the Estimated Average Requirement (EAR). Furthermore, 65% (529/818) took a supplement containing iodine, however, only 32% (259/818) took >150 & mu;g/d. Median intake increased to 188.5 & mu;g/d with the inclusion of I from supplements, however , 41% (380/925) remained below the EAR even after supplementation suggesting inadequate intake in nearly half of the cohort. A similar 48% (467/966) had UIC <150 & mu;g/L. Conclusions: Assessment of iodine status by UIC and intake of iodine from diet and supplements support a high prevalence of iodine insufficiency during pregnancy in this large cohort of US women.

Automated summary

This study investigated iodine intake and iodine status in a large cohort of US pregnant women. The results showed that iodine intake from diet was inadequate and nearly half of the women did not meet the recommended intake even with supplementation. About half of the women also had insufficient urinary iodine concentration. Therefore, there is a high prevalence of iodine insufficiency among pregnant women in the US.