An Iodine Database for Common Korean Foods and the Association between Iodine Intake and Thyroid Disease in Korean Adults

ABSTRACT

BACKGROUND AND OBJECTIVES: Iodine is essential for thyroid hormone production and the iodine intake of Koreans is high. Few studies have examined the association between iodine intake and thyroid disease in the Korean population due to the lack of an iodine database. Therefore, this study established an iodine database, evaluated iodine intake levels, and explored the association between iodine intake and thyroid disease. MATERIALS AND METHODS: We obtained data for 9998 subjects who had both biochemical and dietary data from the 2007-2009 Korea National Health and Nutrition Examination Survey. RESULTS: An iodine database was established for 667 food items. The median iodine intake in the population was 375.4 microg per day. The iodine contribution by food group was 65.6% from seaweed, 18.0% from salted vegetables, and 4.8% from fish. When subjects were divided into five groups across quintiles of iodine intake per 1000 kcal, excluding extreme subjects who consumed above the upper limit, age, sex, income, education, drinking, and smoking differed across the groups. While the energy and fat intakes decreased, other nutrients increased across the quintile groups. The consumption of seaweeds, fish, eggs, and salted vegetables increased across the quintile groups. After adjusting for all potential confounding variables, the odds ratio for thyroid disease in the highest quintile was 1.63 compared to that in the lowest quintile (p for trend=0.0352). CONCLUSION: The iodine intake of the Korean population is high, with high consumption of seaweeds, salted vegetables, and fish positively associated with thyroid disease.