EURRECA—Estimating Iodine Requirements for Deriving Dietary Reference Values

Abstract

Iodine is an essential component of thyroid hormones, and current recommendations for intake are based on urinary iodine excretion, assessment of thyroid size, thyroidal iodine accumulation and turnover, radioactive iodine uptake, balance studies, and epidemiological studies. Dietary iodine is rapidly and almost completely absorbed. The prevalence of inadequate iodine intake is high: 29% of the world's population lives in iodine-deficient areas and 44% of Europe remains mildly iodine deficient. To assess current data and update evidence for setting dietary recommendations for iodine, the EURRECA Network of Excellence has undertaken systematic review and evaluation of (i) the usefulness of iodine status biomarkers (ii) the relationship between iodine status biomarkers and dietary iodine intake, and (iii) the relationship between iodine intake and health outcomes (endemic goiter, hypothyroidism, and cognitive function). This review summarizes the main research outputs: the key findings of the literature review, results of the meta-analyses, and discussion of the main conclusions. Currently, data for relevant intake–status–health relationships for iodine are limited, particularly for population groups such as children under two years, pregnant women, and the elderly. The EURRECA Network developed best practice guidelines for the identification of pertinent iodine studies based on a systematic review approach. This approach aimed to identify comparable data, suitable for meta-analysis, for different countries and across all age ranges. When new data are available, the EURRECA Network best practice guidelines will provide a better understanding of iodine requirements for different health outcomes which could be used to set evidence-based dietary iodine recommendations for optimal health.

Keywords:

• Iodine
• dietary recommendation
• iodine intake
• systematic review
• iodine status
• iodine bioavailability
• iodine requirements
• EURRECA

ACKNOWLEDGMENTS

The authors would like to acknowledge the assistance of Jasna Tepsic, Tamara Popovic, Gordana Petrovic-Oggiano, Aleksandra Arsic, and Cristiana Berti with the data extraction. We thank Rachel Collings for her assistance with the electronic searches and Rachel Hurst for assistance with the Endnote Library. Our sincere thanks to Michael Zimmermann (Swiss Federal Institute of Technology, Switzerland) for his expert advice throughout the EURRECA process. The preparation of this manuscript was coordinated by Rachel Collings from the University of East Anglia and copyediting by EUFIC.

Sources of support: This study received partial financial support from the Commission of the European Communities, specific RTD program “Quality of Life and Management of Living Resources”, within the 6th Framework Programme (contract No. FP6-036196-2 EURRECA: EURopean micronutrient RECommendations Aligned). This manuscript does not necessarily reflect the views of the Commission and in no way anticipates the future policy in this area. This work was in part funded by the Ministry of Education and Science of the Republic of Serbia, project III 41030.