Journal List > Korean J Nutr > v.44(1) > 1043916

Lee and Min: Iodine Intake and Tolerable Upper Intake Level of Iodine for Koreans∗

Abstract

The present study reviewed the effects of excess iodine intake on thyroid function and the incidence of thyroid disease and discussed the scientific basis for establishing a tolerable upper intake level (UL) of iodine for Koreans. ULs are defined as “the highest level of daily nutrient intake that is likely to pose no risk of adverse effects to almost all individuals in the general population.” Koreans consume excess iodine from seaweed, and iodine intake is strongly influenced by seaweed consumption. However, no dose-response data derived from subjects consuming excess iodine frequently but not continuously during a lifetime are available. Therefore, the Korean DRI committee set the iodine UL to reduce the risk of adverse health effects by excess iodine intake for Koreans with distinctive seaweed-eating habits.

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Table 1.
Urinary iodine excretion of Korean normal adults and patients with thyroid disease
References Sample Subjects (n) Urinary iodine excretion 1)
Mean Range
Kim et al. 26) 24 hr urine Normal (245) 3.52 ± 02.28 2) mg/d 0.17-10.37 mg/d
Grave’s disease (27) 5.33 ± 06.28 mg/d 0.92-29.21 mg/d
Primary hypothyroidism (7) 1.07 ± 00.22 mg/d 0.79-01.51 mg/d
Cho et al. 44) Spot urine Normal (67) 0.64 ± 00.06 mg/Lns - 3) 0.23-01.25 mg/L
Simple goiter (39) 0.55 ± 00.09 mg/L - 0.18-00.89 mg/L
Hyperthyroidism (37) 0.88 ± 00.21 mg/L - 0.32-01.30 mg/L
Hypothyroidism (20) 0.56 ± 00.12 mg/L - 0.16-01.00 mg/L
Park et al. 45) Spot urine Normal (184) 3.80 ±0 2.7 mg/L 0.10-15.0 mg/L
Thyroid nodule (53) 2.80 ± 02.7 mg/L 0.10-09.0 mg/L
Hyperthyroidism (62) 4.70 ± 10.8 mg/L 0.10-066.0 mg/L
Chronic thyroiditis (42) 3.20 ± 02.6 mg/L 0.30-08.8 mg/L
Kim et al. 60) 24hr urine or spot urine Normal (40) 1.13 ± 00.65 mg/d4) -3)
(0.67 ± 00.38 mg/creatinine/d)
Kim & Kim 67) 24 hr urine Normal (207) 2.11 ± 00.69 mg/L 0.70-05.04 mg/L
Simple goiter (17) 2.88 ± 01.69 mg/L 1.26-06.43 mg/L
Hyperthyroidism (42) 4.90 ± 07.48 mg/L 1.01-34.9 mg/L
Hypothyroidism (15) 4.57 ± 03.97 mg/L 1.17-12.75 mg/L
Thyroid cancer (11) 6.18 ± 04.77 mg/L∗∗ 1.10-14.35 mg/L

1) Urinary iodine was measured by electrode method

2) Mean ± SD

3) Data were not reported

4) Calculated by applying 24 hr urinary creatinine excretion as 1.68 g/d based on data from Vejbjerg et al. (Thyroid 2009; 19: 1281-1286) ns: not significantly different

p < 05

∗∗ p < 001 when compared with normal control

Table 2.
Derivation of Tolerable Upper Intake Levels (UL) of iodine for Koreans
Age Weight (kg) Calculation UL (μg/d) References
Infants (mo)
00-5 06.2 UL = 325 μg/L∗0.75L/d = 243.8 ≑ 250 μg/d 250 Nishiyama et al. 75)
06-11 08.9 UL = 325 μg/L∗0.75L/d = 243.8 ≑ 250 μg/d 250
Children (yr)
001-2 12.2 UL = [12.2 kg/( 24.6 + 34.8) kg/2∗500 μg/d]/2 + [12.2 kg/ (6.2 + 8.9)kg/2∗250 μg/d]/2 = ( 205 + 404)/2 = 305 ≑ 300 μg/d 300  
03-5 17.2 UL = 17.2 kg/( 24.6 + 34.8) kg/2∗500 μg/d = 289.6 ≑ 300 μg/d 300  
Males (yr)
06-8 250 UL = 500 μg/d 500 Zimmermann et al. 52)
09-11 35.7 UL = 500 μg/d 500
12-14 50.5 UL = 2,400 μg/d∗47.5 kg/65.8 kg = 1,732 ≑ 1,700 μg/d 1,700  
15-18 62.1 UL = 2,400 μg/d∗53.6 kg/65.8 kg = 1,955 ≑ 1,900 μg/d 1,900  
19-29 65.8   2,400  
30-49 63.6   2,400  
50-64 60.6 UL = LOAEL 3,600 μg/d ÷ UF 1.5 = 2,400 μg/d 2,400 67) Kim & Kim
65-74 59.2   2,400  
75+ 59.2   2,400  
Females
06-8 24.6 UL = 500 μg/d 500 Zimmermann et al. 52)
09-11 34.8 UL = 500 μg/d 500
12-14 47.5 UL = 2,400 μg/d∗47.5 kg/65.8 kg = 1,732 ≑ 1,700 μg/d 1,700  
15-18 53.4 UL = 2,400 μg/d∗53.6 kg/65.8 kg = 1,955 ≑ 1,900 μg/d 1,900  
19-29 56.3   2,400  
30-49 54.2   2,400  
50-64 52.2 UUL = LOAEL 3,600 μg/d ÷ UF 1.5 = 2,400 μg/d 2,400 Kim & Kim 67)
65-74 50.2   2,400  
75+ 50.2   2,400  
Pregnant - - -
Lactating - - -
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