Journal List > Int J Thyroidol > v.8(2) > 1082720

Han, Ju, Paik, Song, and Park: 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 μ g 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.

References

1. Kim JH, Park SJ, Kim SE, Lee KH, Cho IK, Jang SI, et al. Prevalence of thyroid nodules detected by ultrasonography in adult men attending health check-ups. J Korean Endocr Soc. 2007; 22(2):112–7.
crossref
2. Suk JH, Kim TY, Kim MK, Kim WB, Kim HK, Jeon SH, et al. Prevalence of ultrasonographically-detected thyroid nodules in adults without previous history of thyroid disease. J Korean Endocr Soc. 2006; 21(5):389–93.
crossref
3. Yim CH, Oh HJ, Chung HY, Han KO, Jang HC, Yoon HK, et al. Prevalence of thyroid nodules detected by ultrasonography in womens attending health check-ups. J Korean Soc Endocrinol. 2002; 17(2):183–8.
4. Kim SY, Hyun MK. A evidencebased study on the effectiveness of thyroid cancer screening test. National Evidence-based Healthcare Collaborating Agency (NECA). Seoul, Korea;. 2012.
5. Choi HS, Park YJ, Kim HK, Choi SH, Lim S, Park DJ, et al. Prevalence of subclinical hypothyroidism in two population based-cohort: Ansung and KLoSHA cohort in Korea. J Korean Thyroid Assoc. 2010; 3(1):32–40.
6. Jung KW, Won YJ, Kong HJ, Oh CM, Cho H, Lee DH, et al. Cancer statistics in Korea: incidence, mortality, survival, and prevalence in 2012. Cancer Res Treat. 2015; 47(2):127–41.
crossref
7. Laurberg P, Cerqueira C, Ovesen L, Rasmussen LB, Perrild H, Andersen S, et al. Iodine intake as a determinant of thyroid disorders in populations. Best Pract Res Clin Endocrinol Metab. 2010; 24(1):13–27.
crossref
8. Lee HS, Min H. Iodine intake and tolerable upper intake level of iodine for Koreans. Korean J Nutr. 2011; 44(1):82–91.
crossref
9. Teng W, Shan Z, Teng X, Guan H, Li Y, Teng D, et al. Effect of iodine intake on thyroid diseases in China. N Engl J Med. 2006; 354(26):2783–93.
crossref
10. Vejbjerg P, Knudsen N, Perrild H, Laurberg P, Carle A, Pedersen IB, et al. Lower prevalence of mild hyperthyroidism related to a higher iodine intake in the population: prospective study of a mandatory iodization programme. Clin Endocrinol (Oxf). 2009; 71(3):440–5.
crossref
11. Konno N, Makita H, Yuri K, Iizuka N, Kawasaki K. Association between dietary iodine intake and prevalence of subclinical hypothyroidism in the coastal regions of Japan. J Clin Endocrinol Metab. 1994; 78(2):393–7.
crossref
12. Kim JY, Moon SJ, Kim KR, Sohn CY, Oh JJ. Dietary iodine intake and urinary iodine excretion in normal Korean adults. Yonsei Med J. 1998; 39(4):355–62.
crossref
13. Kim JY, Kim KR. Dietary iodine intake and urinary iodine excretion in patients with thyroid diseases. Yonsei Med J. 2000; 41(1):22–8.
crossref
14. Imaeda N, Kuriki K, Fujiwara N, Goto C, Tokudome Y, Tokudome S. Usual dietary intakes of selected trace elements (Zn, Cu, Mn, I, Se, Cr, and Mo) and biotin revealed by a survey of four-season 7-consecutive day weighed dietary records in middle-aged Japanese dietitians. J Nutr Sci Vitaminol (Tokyo). 2013; 59(4):281–8.
crossref
15. Kang TS. Monitoring of iodine in foods for estimation of dietary intake. Naterional Institute of Food and Drug Safety Evaluation;2012.
16. Lee JY. Iodine analysis method establishment and content monitoring of food. Global Health Care. Korea National Institute of Food and Drug Safety;2006.
17. Kim BH. Development of nutrient database – 3. Mineral composition of foods −. Korea Health Industry Development Institute;2003.
18. Moon SJ, Kim JY, Chung YJ, Chung YS. The iodine content in common Korean foods. Korean J Nutr. 1998; 31(2):206–12.
19. National Rural Living Science Institute. Food composition table. Rural Development Administration;2006.
20. Chang NS, Cho YW, Kim WJ. Iodin intake and excretion of the patients with thyroid disease. Korean J Nutr. 1994; 27(10):1037–47.
21. The Korean Nutrition Society. Food values. The Korean Nutrition Society;2009.
22. Kim EH, Choi TI, Park YK. Dietary iodine intake and the association with subclinical thyroid dysfunction in male workers. Korean J Nutr. 2012; 45(3):218–28.
crossref
23. Ristic-Medic D, Dullemeijer C, Tepsic J, Petrovic-Oggiano G, Popovic T, Arsic A, et al. Systematic review using metaanalyses to estimate dose-response relationships between iodine intake and biomarkers of iodine status in different population groups. Nutr Rev. 2014; 72(3):143–61.
crossref
24. Luo Y, Kawashima A, Ishido Y, Yoshihara A, Oda K, Hiroi N, et al. Iodine excess as an environmental risk factor for autoimmune thyroid disease. Int J Mol Sci. 2014; 15(7):12895–912.
crossref
25. Michikawa T, Inoue M, Shimazu T, Sawada N, Iwasaki M, Sasazuki S, et al. Seaweed consumption and the risk of thyroid cancer in women: the Japan Public Health Center-based Prospective Study. Eur J Cancer Prev. 2012; 21(3):254–60.
26. Matsubayashi S, Mukuta T, Watanabe H, Fuchigami H, Taniguchi J, Chinen M, et al. Iodine-induced hypothyroidism as a result of excessive intake of confectionery made with tangle weed, Kombu, used as a low calorie food during a bulimic period in a patient with anorexia nervosa. Eat Weight Disord. 1998; 3(1):50–2.
crossref
27. Cho NH, Choi HS, Kim KW, Kim HL, Lee SY, Choi SH, et al. Interaction between cigarette smoking and iodine intake and their impact on thyroid function. Clin Endocrinol (Oxf). 2010; 73(2):264–70.

Fig. 1.
The distribution of iodine intake in the Korean adults population aged 20 or more using the data from 2007–2009 Korea National Health and Nutrition Examination Survey. Box: Q3-Q1 (Interquartile range), Q1: 25 th percentile, Q3: 75 th percentile,
ijt-8-170f1.tif
Fig. 2.
The average and range of iodine intake across quintile and extreme group. Quintile group was classified based on the iodine intake per 1000 kcal.
ijt-8-170f2.tif
Table 1.
Composition of the table of iodine values for common Korean foods
Food group Number of food items
Matched values Imputed values Assigned as zero Sum
Grain and its products 32 31 1 64
Potatoes 4 5 2 11
Sugar and sweets 3 9 3 15
Legumes 7 15 0 22
Nuts and seeds 6 9 1 16
Vegetables 45 65 28 138
Mushrooms 4 8 2 14
Fruits 27 28 8 63
Meat and its products 11 10 3 24
Eggs 3 1 0 4
Fishes 38 58 35 131
Seaweeds 5 15 0 20
Milk and dairy products 7 3 1 11
Oils 5 9 1 15
Beverages 15 11 13 39
Seasonings 14 6 15 35
Processed foods 2 4 6 12
Others 6 4 23 33
Total number of food items 234 (35.1%) 291 (43.6%) 142 (21.3%) 667
Frequency 448,110 (87.7%) 54,230 (10.6%) 8,418 (1.6%) 510,758
Table 2.
The contribution of iodine intake according to food groups in total population
Food group Frequency Median of iodine intake Sum of iodine intake % of total
Grains (곡류) 56,913 1.1 211,069 2.5
Potatoes (감자․전분류) 5,964 0.9 10,271 0.1
Sugar and sweets (당류) 22,235 0.0 1,609 0.0
Legumes (두류) 14,763 1.2 51,761 0.6
Nuts and seeds (견과․종실류) 18,090 0.0 2,060 0.0
Vegetables (채소류) 134,122 0.0 53,540 0.6
Salted vegetable (절임 채소류) 30,611 38.7 1,510,373 18.0
Mushrooms (버섯류) 3,304 0.4 2,395 0.0
Fruits (과일류) 11,121 4.5 83,954 1.0
Meat (육류) 13,924 3.7 153,476 1.8
Eggs (난류) 7,409 7.5 89,973 1.1
Fishes (어류) 28,215 5.6 400,643 4.8
Seaweeds (패류) 8,867 147.3 5,495,417 65.6
Milk & dairy products (우유류) 4,115 63.6 243,492 2.9
Oils (유지류) 35,910 0.0 916 0.0
Beverages (음료류) 16,904 0.1 23,886 0.3
Seasonings (양념류) 97,038 0.0 36,754 0.4
Processed foods (가공식품류) 481 1.3 1,420 0.0
Others (기타) 772 0.0 0 0.0
Total 510,758     100.0
Table 3.
Socio-demographic characteristics of study subjects
  Quintile of iodine intake (per 1,000 kcal) p for trend Extreme group (n=792) P Q5vsEx
Q1
(n=1,841)
Q2
(n=1,841)
Q3
(n=1,842)
Q4
(n=1,841)
Q5
(n=1,841)
Age (year) 42.7.5 40.6.4 40.5.4 40.9.4 40.5.4 0.0053 40.6.5 0.8871
BMI (kg/m2) 23.2.1 23.3.1 23.3.1 23.2.1 23.2.1 0.7461 23.2.1 0.9981
Sex (%)
Male 49.4 50.6 48.7 47.2 46.9 0.0449 57.6 <0.0001
Income level (%)
Low 28.1 22.5 23.6 22.3 24.1 0.0162 19.4 0.0449
Medium-low 24.9 25.1 24.8 26.6 23.7   22.3  
Medium-high 25.3 26.2 25.7 25.7 25.1   30.0  
High 21.7 26.2 25.9 25.4 27.1   28.3  
Education level (%)
Elementary or less 20.1 13.2 11.8 11.8 11.5 <0.0001 8.9 0.0018
Middle school 9.9 9.4 8.5 10.8 9.9   8.5  
High school 42.5 43.4 44.6 42.6 45.6   42.2  
College or more 27.5 34.0 35.1 34.8 33.0   40.4  
Residential area (%)
Metropolitan 45.9 46.7 47.0 47.7 47.0 0.7733 43.3 0.4287
Small city 36.4 39.2 39.8 35.8 36.2   40.6  
Rural 17.7 14.1 13.2 16.6 16.8   16.1  
Drinking (%)
Yes 62.0 63.6 60.4 59.4 59.6 0.0356 63.8 0.0830
Current smoking (%)
Yes 30.1 30.9 26.7 24.9 25.1 0.0478 27.3 0.0072
Physical activity (%)
Yes 15.8 16.5 18.9 18.2 17.1 0.2233 18.6 0.4777
All models were analyzed using the complex sampling design effect and appropriate sampling weights of the national survey.

BMI: body mass index

Table 4.
Nutrient intake of study subjects
  Quintile of iodine intake (per 1,000 kcal) p for trend Extreme group (n=792) P Q5vsE
Q1
(n=1,841)
Q2
(n=1,841)
Q3
(n=1,842)
Q4
(n=1,841)
Q5
(n=1,841)
Iodine (μ g) 114.3±4.6 234.6±3.1 366.5±2.9 540.9±4.0 1,189.4±13.7 <0.0001 4,700.1±141.0 <0.0001
Energy (kcal) 2,004.2±25.5 2,002.4±23.3 1,890.8±22.0 1,814.0±21.0 1,751.5±20.1 <0.0001 2,079.7±33.9 <0.0001
Carbohydrate (g) 294.7±2.6 301.4±2.4 302.9±2.1 304.6±2.0 306.9±2.0 <0.0001 304.2±3.6 0.7952
Protein (g) 58.7±0.7 63.7±0.6 67.1±0.7 67.1±0.6 67.0±0.6 <0.0001 65.1±1.0 0.3964
Fat (g) 35.7±0.7 36.4±0.7 35.7±0.5 35.2±0.6 34.2±0.6 0.0237 33.3±0.9 0.7898
Calcium (mg) 329.6±7.3 427.2±7.5 483.8±7.4 532.1±9.2 555.2±11.0 <0.0001 555.4±15.8 0.7667
Phosphorous (mg) 946.3±8.6 1,050.0±8.3 1,124.6±8.5 1,166.8±8.9 1,179.9±10.5 <0.0001 1,142.7±15.9 0.2043
Iron (mg) 12.0±0.4 12.6±0.2 13.2±0.2 14.4±0.3 14.7±0.3 <0.0001 15.0±0.4 0.4100
Sodium (mg) 3,661.3±68.8 4,367.3±64.3 4,951.6±70.4 5,433.1±73.1 5,706.4±93.8 <0.0001 5,829.2±131.1 0.4626
Potassium (mg) 2,406.6±33.5 2,650.0±30.7 2,839.2±34.3 3,031.9±31.7 3,172.4±31.8 <0.0001 3,393.0±53.0 0.0001
Vitamin A (μ gRE) 537.8±22.9 648.7±21.2 741.4±23.1 847.2±25.0 947.9±32.8 <0.0001 856.9±34.8 0.1412
Thiamin (mg) 1.1±0.0 1.2±0.0 1.2±0.0 1.3±0.0 1.2±0.0 <0.0001 1.2±0.0 0.0593
Riboflavin (mg) 0.8±0.0 1.0±0.0 1.1±0.0 1.2±0.0 1.2±0.0 <0.0001 1.2±0.0 0.0639
Niacin (mg) 14.4±0.2 14.7±0.2 15.2±0.2 15.2±0.2 15.6±0.2 <0.0001 15.7±0.3 0.4287
Vitamin C (mg) 83.0±2.9 91.2±2.5 102.0±2.7 109.0±2.7 113.9±3.0 <0.0001 115.1±5.8 0.7893
% energy from                
Carbohydrate 69.4±0.4 68.4±0.3 68.2±0.3 68.5±0.3 69.0±0.3 0.6137 69.3±0.4 0.4228
Protein 13.4±0.1 14.1±0.1 14.7±0.1 14.8±0.1 14.8±0.1 <0.0001 14.6±0.2 0.3278
Fat 17.2±0.3 17.5±0.3 17.1±0.2 16.6±0.2 16.2±0.2 0.0001 16.1±0.4 0.6103

Values are expressed as adjusted means±standard error.

All models were analyzed using the complex sampling design effect with appropriate sampling weights of the national survey after adjusted for age, sex, income, education, smoking and energy intake (except the model for energy intake).

Table 5.
Food group intakes across quintile of iodine intake including extreme group
  Quintile of iodine intake (per 1,000 kcal) p for trend Extreme group (n=792) P Q5vsE
Q1
(n=1,841)
Q2
(n=1,841)
Q3
(n=1,842)
Q4
(n=1,841)
Q5
(n=1,841)
Grains 292.8±4.3 298.8±4.0 298.3±3.7 297.3±3.4 294.3±3.6 0.9265 293.4±6.5 0.5552
Potatoes 39.5±3.6 35.0±3.0 35.8±4.0 33.9±2.5 28.5±2.1 0.0072 29.0±5.1 0.7402
Sugar and sweets 9.3±0.5 8.3±0.5 7.4±0.3 7.3±0.4 7.9±0.4 0.0066 7.5±0.6 0.8763
Legumes 29.8±2.8 39.2±2.4 40.7±2.6 38.0±2.1 38.2±2.7 0.0330 36.5±3.7 0.4868
Nuts and seeds 2.6±0.2 2.8±0.3 2.3±0.2 2.7±0.3 3.2±0.4 0.3473 2.1±0.6 0.4099
Vegetables 189.4±5.5 191.0±5.2 186.3±5.3 180.1±5.6 175.4±4.8 0.0104 181.3±7.0 0.0229
Salted vegetables 53.8±2.2 107.3±2.5 145.9±3.0 189.9±3.6 186.9±5.2 <0.0001 160.8±8.3 0.0004
Mushrooms 4.0±0.5 3.5±0.4 3.9±0.6 4.8±0.6 4.2±0.4 0.1453 3.4±0.6 0.2965
Fruits 145.4±9.6 168.2±9.9 160.5±9.1 151.2±8.1 163.6±8.9 0.5309 168.6±13.8 0.5271
Meat & its products 92.1±4.9 84.1±4.6 78.4±4.1 71.9±3.8 64.8±3.3 <0.0001 61.1±5.3 0.9542
Eggs 14.1±1.1 21.1±1.4 23.5±1.3 23.1±1.2 20.3±1.3 0.0002 22.1±1.9 0.3231
Fishes 33.5±2.2 43.3±2.3 54.4±2.8 55.9±2.4 63.0±2.8 <0.0001 62.2±4.3 0.9793
Seaweeds 0.0±0.1 0.6±0.1 2.0±0.2 3.7±0.2 10.7±0.5 <0.0001 28.9±1.6 <0.0001
Milk & dairy products 21.9±3.1 55.8±4.5 75.8±4.5 100.3±7.1 77.9±5.0 <0.0001 56.5±6.7 0.0027
Oils 8.0±0.3 7.7±0.3 7.2±0.2 6.8±0.2 7.6±0.2 0.0637 7.8±0.4 0.2156
Beverages 245.2±14.7 175.0±12.5 144.3±10.9 147.8±10.5 145.3±10.0 <0.0001 194.6±22.5 0.1105
Seasonings 36.2±1.1 34.1±1.2 32.3±1.4 32.4±1.6 34.3±1.0 0.1073 36.9±1.8 0.0210
Processed foods 5.7±1.1 3.5±0.9 7.1±1.9 4.3±1.1 2.9±0.9 0.1225 3.0±1.0 0.8793
Others 0.4±0.2 0.4±0.1 0.3±0.1 0.5±0.2 0.4±0.1 0.7514 0.2±0.1 0.1264

Values are expressed as adjusted means±standard error with appropriate sampling weights.

All models were analyzed using the complex sampling design effect with appropriate sampling weights of the national survey after adjusted for age, sex, income, education, smoking and energy intake (except the model for energy intake).

Table 6.
The odds ratio for thyroid disease across the quintile of iodine intakes
  Quintile of iodine intake (per 1,000 kcal) Extreme group P for trend2) p for trend3)
Q1 Q2 Q3 Q4 Q5
Age, sex-adjusted 1.00 1.19
(0.76–1.86)
1.50
(0.97–2.31)
1.37
(0.89–2.11)
1.84
(1.17–2.88)
1.31
(0.72–2.40)
0.0066 0.0202
Multivariate1) 1.00 1.10
(0.70–1.72)
1.40
(0.91–2.16)
1.27
(0.82–1.96)
1.63
(1.03–2.59)
1.20
(0.65–2.21)
0.0352 0.0735

All models were analyzed using the complex sampling design effect and appropriate sampling weights of the national survey were applied.

1) Adjusted for age, sex, income, education, drinking, smoking and energy intake

2) Excluding extreme group

3) Including extreme group

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