Published online Feb 28, 2021.
https://doi.org/10.5720/kjcn.2021.26.1.48
Estimation of Dietary Iodine Intake of Koreans through a Total Diet Study (TDS)
Abstract
Objectives
This study was conducted to estimate the dietary iodine intake of Koreans by a Total Diet Study (TDS) which provides ‘closer-to-real’ estimates of exposure to hazardous materials and nutrients through an analysis of table-ready (cooked) samples of foods.
Methods
Dietary intake data from 2013–2017 Korea National Health and Nutrition Examination Survey (KNHANES) was used to select representative foods (RFs) for iodine analysis. A total of 115 RFs were selected and 158 ‘RF × cooking method-combination’ pairs were derived by pairing each RF to corresponding cooking method(s) used more frequently. RFs were collected from 9 mega-markets in 9 metropolitan cities nationwide and mixed into composites prior to cooking preparation to a ‘table ready’ state for iodine analysis by inductively coupled plasma mass spectrometry. Iodine intake of Koreans was estimated based on the food intake data of the 2016–2018 KNHANES.
Results
High iodine content was detected in seaweeds such as sea mustard and kelp. The mean iodine intake/capita/day was 418.4 µg and the median value was 129.0 µg. Seaweeds contributed to 77.4% of the total iodine intake and the contribution by food item was as follows: sea mustard (44.0%), kelp (20.4%), laver (13.1%), milk (3.9%), egg (3.5%). Compared to the Dietary Reference Intakes for Koreans 2020, the proportion of people with iodine intake exceeding the tolerable upper intake level or below the estimated average requirement was high in the physiologically vulnerable groups (infants, children, pregnant women, and lactating women).
Conclusions
The results, drawn from a TDS, are regarded closer to real estimates for iodine intake of Koreans compared with values in existing literature, which were based on a very limited variety of foods. On the other hand, it seems necessary to seek out solutions for the problematic iodine intake among physiologically vulnerable groups through in-depth analyses on food intake data collected with significant scale & quality.
Fig. 1
Total Diet Study (TDS) procedure
Fig. 2
Preparation of food samples in Total Diet Study
Fig. 3
2) Tolerable upper intake level
The Proportion of subjects with iodine intake below EAR1), adequate level (EAR~UL2)) and above UL
1) Estimated average requirement
Table 1
Proportion of foods containing iodine in each food group
Table 2
Iodine concentration according to foods and cooking methods
Table 3
Distribution of estimated daily dietary iodine intakes by age and sex
Table 4
Contribution of each food group to daily iodine intake
Table 5
Distribution of estimated daily dietary iodine intakes in pregnant and breast-feeding women
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