Research needs for assessing iodine intake, iodine status, and the effects of maternal iodine supplementation

The Office of Dietary Supplements of the NIH convened 3 workshops on iodine nutrition in Rockville, Maryland, in 2014. The purpose of the current article is to summarize and briefly discuss a list of research and resource needs developed with the input of workshop participants. This list is composed of the basic, clinical, translational, and population studies required for characterizing the benefits and risks of iodine supplementation, along with related data, analyses, evaluations, methods development, and supporting activities. Ancillary studies designed to use the participant, biological sample, and data resources of ongoing and completed studies (including those not originally concerned with iodine) may provide an efficient, cost-effective means to address some of these research and resource needs. In the United States, the foremost question is whether neurobehavioral development in the offspring of mildly to moderately iodine-deficient women is improved by maternal iodine supplementation during pregnancy. It is important to identify the benefits and risks of iodine supplementation in all population subgroups so that supplementation can be targeted, if necessary, to avoid increasing the risk of thyroid dysfunction and related adverse health effects in those with high iodine intakes. Ultimately, there will be a need for well-designed trials and other studies to assess the impact of maternal supplementation on neurodevelopmental outcomes in the offspring. However, 2 basic information gaps loom ahead of such a study: the development of robust, valid, and convenient biomarkers of individual iodine status and the identification of infant and toddler neurobehavioral development endpoints that are sensitive to mild maternal iodine deficiency during pregnancy and its reversal by supplementation.