Estimation of Dietary Iodine Intake of Koreans through a Total Diet Study (TDS)

Jeeyeon Lee; Yoonjae Yeoh; Min Jeong Seo; Gae Ho Lee; Cho-il Kim

doi:10.5720/kjcn.2021.26.1.48

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Estimation of Dietary Iodine Intake of Koreans through a Total Diet Study (TDS): Jeeyeon Lee, Yoonjae Yeoh, Min Jeong Seo, Gae Ho Lee, Cho-il Kim; Korean Journal of Community Nutrition 2021;26(1):48-55.
DOI: https://doi.org/10.5720/kjcn.2021.26.1.48
Published online: February 28, 2021

¹Principal researcher, Nutrition Policy & Promotion Team, Department of Healthcare Service Innovation, Korea Health Industry Development Institute, Chungcheongbuk-do, Korea

²Graduate student, Department of Health Administration, Kongju National University Graduate School, Korea

³Researcher, Nutrition Policy & Promotion Team, Department of Healthcare Service Innovation, Korea Health Industry Development Institute, Chungcheongbuk-do, Korea

⁴Team leader, Korea Research Institute of Analytical Technology, Daejeon, Korea

⁵Emeritus Professor, Korea Research Institute of Analytical Technology, Daejeon, Korea

⁶Executive Director, Korea Health Industry Development Institute, Chungcheongbuk-do, Korea

Corresponding author: Cho-il Kim, Tel: +82-43-713-8401, Fax: +82-43-713-8907,
Email: kimci@khidi.or.kr

Received: 27 January 2021 • Revised: 23 February 2021 • Accepted: 23 February 2021

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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 ㎍ and the median value was 129.0 ㎍. 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.

Keywords: total diet study; dietary iodine intake; representative foods; iodine content

Korean J Community Nutr. 2021 Feb;26(1):48-55. Korean.
Published online Feb 28, 2021.
https://doi.org/10.5720/kjcn.2021.26.1.48

Original Article

Estimation of Dietary Iodine Intake of Koreans through a Total Diet Study (TDS)

Jeeyeon Lee

,¹^,² Yoonjae Yeoh

,³ Min Jeong Seo

,⁴ Gae Ho Lee

,⁵ and Cho-il Kim

⁶

Author information

Author notes

- ¹Principal researcher, Nutrition Policy & Promotion Team, Department of Healthcare Service Innovation, Korea Health Industry Development Institute, Chungcheongbuk-do, Korea.
- ²Graduate student, Department of Health Administration, Kongju National University Graduate School, Korea.
- ³Researcher, Nutrition Policy & Promotion Team, Department of Healthcare Service Innovation, Korea Health Industry Development Institute, Chungcheongbuk-do, Korea.
- ⁴Team leader, Korea Research Institute of Analytical Technology, Daejeon, Korea.
- ⁵Emeritus Professor, Korea Research Institute of Analytical Technology, Daejeon, Korea.
- ⁶Executive Director, Korea Health Industry Development Institute, Chungcheongbuk-do, Korea.
Corresponding author: Cho-il Kim. Korea Health Industry Development Institute, 187 Osongsaengmyeong-2-ro, Osong-eup, Heungduk-gu, Cheongju-si, Choongbuk 28159, Korea. Tel: +82-43-713-8401, Fax: +82-43-713-8907, Email: kimci@khidi.or.kr

Received January 27, 2021; Revised February 23, 2021; Accepted February 23, 2021.

This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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.

Keywords

total diet study; dietary iodine intake; representative foods; iodine content

Figures

Fig. 1
Total Diet Study (TDS) procedure

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Fig. 2
Preparation of food samples in Total Diet Study

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Fig. 3
The Proportion of subjects with iodine intake below EAR¹⁾, adequate level (EAR~UL²⁾) and above UL
1) Estimated average requirement

2) Tolerable upper intake level

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Tables

Table 1
Proportion of foods containing iodine in each food group

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Table 2
Iodine concentration according to foods and cooking methods

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Table 3
Distribution of estimated daily dietary iodine intakes by age and sex

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Table 4
Contribution of each food group to daily iodine intake

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Table 5
Distribution of estimated daily dietary iodine intakes in pregnant and breast-feeding women

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Figure & Data

References

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