Assessment of dietary iodine intake and its sources among Koreans: a cross-sectional analysis from the Korea National Health and Nutrition Examination Survey 2019-2021

Abstract

Background/objectives: Iodine is an essential mineral that is critical for humans, as inadequate and excessive intake can lead to adverse health outcomes. Data on dietary iodine intake and adequacy among Koreans remain limited. This study aimed to estimate the dietary iodine intake of Koreans, assess the adequacy of intake, and examine the primary dietary sources of iodine in the Korean population.

Subjects/methods: This study analyzed data from 18,895 participants aged ≥ 1 yr obtained from the Korea National Health and Nutrition Examination Survey (KNHANES) 2019-2021. Dietary iodine intake was calculated using a newly constructed iodine database applied to KNHANES data. Intake levels were compared against the sex- and age-specific reference values outlined in the Korean Dietary Reference Intakes 2020. Insufficient intake was below the estimated average requirement (EAR), while excessive intake was above the tolerable upper intake level (UL).

Results: The median iodine intake of Koreans aged ≥ 1 yr was 114 µg/d, corresponding to 123% of the EAR. Approximately 4 in 10 Koreans did not meet the EAR, one exceeded the UL, and only 5 had adequate iodine intake. Excessive intake was most prevalent among children under 12 yrs of age. Two-thirds of iodine intake came from plant-based foods, with seaweed, eggs, fish, milk, and grains identified as the major dietary contributors.

Conclusion: Koreans' median dietary iodine intake appears adequate; however, a significant proportion exhibit insufficient or excessive intake. Further research is needed to estimate usual iodine intake and develop strategies for addressing problematic iodine intake.

Keywords: Iodine; South Korea; diet; food analysis; nutrition surveys; seaweed.