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The basic study information is shown in Supplementary Table S1 (available in www.besjournal.com). The study investigated the age, gender, body mass index (BMI), UIC, SIC, TVOL, dining places, and intake of iodine-rich processed foods in 5,669 SAC. It also analyzed the effects of different sources of iodine intake on children’s iodine nutritional status, goiter rate (GR), and thyroid nodules. The results found that iodized salt remained the primary source of daily iodine intake for children and contributed the most to total iodine intake. In contrast, iodine intake from iodine-rich processed foods was associated with the TVOL in children. In addition, the use of non-iodized salt in iodine-rich processed foods or when eating out had less of an impact on children’s iodine nutritional status.
Baseline characteristics n Gender Age BMI
(kg/m2, mean ± SD)Boys, n (%) Girls, n (%) 8, n (%) 9, n (5) 10, n (%) Region Xinjiang 804 403 (50.1) 401 (49.9) 227 (28.2) 337 (41.9) 233 (29.0) 16.0 ± 2.4 Sichuan 804 403 (50.1) 401 (49.9) 311 (38.7) 288 (35.8) 205 (25.5) 16.3 ± 2.7 Shanxi 822 417 (50.7) 405 (49.3) 153 (18.6) 302 (36.7) 327 (39.8) 17.2 ± 3.7 Liaoning 800 391 (48.9) 409 (51.1) 226 (28.3) 359 (44.9) 215 (26.9) 18.1 ± 3.7 Fujian 815 403 (49.4) 412 (50.6) 278 (34.1) 272 (33.4) 265 (32.5) 17.1 ± 3.2 Anhui 800 399 (49.9) 401 (50.1) 247 (30.9) 280 (35.0) 273 (34.1) 17.1 ± 3.4 Hubei 824 398 (48.3) 426 (51.7) 281 (34.1) 263 (31.9) 255 (30.9) 16.8 ± 3.2 Economical level High 2,806 1,394 (49.7) 1,412 (50.3) 848 (30.2) 1,072 (38.2) 864 (30.8) 17.4 ± 3.6 Low 2,864 1,420 (49.6) 1,444 (50.4) 876 (30.6) 1,029 (35.9) 909 (31.7) 16.7 ± 3.1 Geographical features Mountain 2,030 1,010 (49.8) 1,020 (50.2) 596 (29.4) 808 (39.8) 608 (30.0) 16.7 ± 3.1 Plain 1,825 910 (49.9) 915 (50.1) 542 (29.7) 680 (37.3) 549 (30.1) 16.8 ± 3.4 Coastal 800 398 (49.8) 402 (50.3) 265 (33.1) 264 (33.0) 271 (33.9) 17.7 ± 3.4 Inland 1,015 496 (48.9) 519 (51.1) 321 (31.6) 349 (34.4) 345 (34.0) 17.3 ± 3.5 Total 5,669 2,809 (49.6) 2,854 (50.4) 1,724 (30.4) 2,101 (37.1) 1,773 (31.3) 17.0 ± 3.3 Table S1. Basic information of school-age children
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SAC had the largest proportion of meals at home (78.7% of all eating occasions; Fujian had the highest at 92.0%; Sichuan had the lowest at 64.3%), as shown in Table 1. The next was school canteens accounting for 15.1% (Sichuan was the highest at 26.9%; Fujian was the lowest at 2.3%), and other dining places had a total of 6.1%. The ratio of eating at home to eating in a canteen was 5.0:1, and that of eating at home to eating away from home was 3.8:1. According to the analysis of the three meals of children in one day, the proportions of dining at home for breakfast, lunch, and dinner were higher compared with other dining places (85.0% for breakfast; 57.7% for lunch; and 93.4% for dinner), and the proportion of dining in a canteen for lunch could also reach 37.7%.
Region Dining iocation (%) Home/other
(x:1)Home/canteen
(x:1)Home Canteen Take-out Restaurant Street
foodSmall
tableCatering
pointProvinces Xinjiang 86.2 13.0 0.5 0.0 0.0 0.0 0.0 6.2 6.6 Sichuan 64.3 26.9 0.4 2.4 2.1 3.2 0.0 1.8 2.4 Shanxi 89.6 4.6 0.8 1.4 1.4 0.5 0.0 8.6 19.4 Liaoning 74.2 23.1 0.1 0.8 0.6 0.2 0.1 2.9 3.2 Fujian 92.0 2.3 0.2 1.6 1.7 0.8 1.1 11.5 27.2 Anhui 77.7 13.9 0.1 0.7 4.0 0.7 2.5 3.5 4.7 Hubei 67.2 22.0 0.2 1.2 8.4 0.2 0.1 2.1 3.0 3 meals Breakfast 85.0 5.2 0.1 1.1 6.8 0.4 0.0 — — Lunch 57.7 37.7 0.4 1.0 0.4 1.0 1.5 — — Dinner 93.4 2.4 0.4 1.5 0.7 1.0 0.1 — — Total 78.7 15.1 0.3 1.2 2.6 0.8 0.5 3.8 5.0 Table 1. The proportion of children eating in different dining places and proportion of dining places for three meals a day
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As shown in Table 2, the MWIC was 3.8 (1.7–6.3) μg/L [Liaoning was the highest at 9.4 (5.3–13.2) μg/L; Sichuan was the lowest at 1.9 (1.4–3.3) μg/L]. A total of 5,646 salt samples were collected and detected. The mean SIC ± SD was 24.8 ± 5.8 mg/kg, and the CRIS and CRQIS were 96.9% and 92.6%, respectively. The CRIS and CRQIS in all provinces met the elimination standard of iodine deficiency disease except in Fujian, where the CRIS was 89.7%, and the CRQIS was 86.1%. The median iodine intake of SACs through water was 2.7 (1.1–4.4) μg/d, and the highest was Liaoning [6.6 (3.3–9.4) μg], the lowest was Sichuan [1.3 (0.6–4.1) μg]. The average salt intake in SAC was 8.9 g. The average iodine intake of SACs through iodized salt was 220.5 ± 62.9 μg, and the highest was Xinjiang (295.4 ± 44.0 μg), and the lowest was Fujian (152.0 ± 54.4 μg). The median daily iodine intake of SAC through iodine-rich processed foods was 4.1 (1.5–8.7) μg, and the highest iodine intake for children from processed foods was Hubei [6.7 (2.8–17.1) μg] [43.2 (12.7–51.5) μg in Ezhou, Hubei], the lowest was Xinjiang [1.1 (0.5–3.8) μg] [0.7 (0.1–0.7) μg in Yining, Xinjiang]. Figure 1 presents the proportional differences in a graph. Iodine intakes mainly come from the consumption of iodized salt, accounting for 79.2%, followed by cooked food (18.4%), processed foods (1.5%) and water (1.0%). Due to the geographical location and economic conditions, children living in Xinjiang consume fewer iodine-rich processed foods and may be affected by consuming iodine oil capsules. So, after excluding the data from Xinjiang and reanalyzing the overall data, the percentage of children’s daily iodine intake from water, iodized salt, iodine-rich processed foods, and cooked food was 1.0%, 76.4%, 1.8%, and 20.9%, respectively.
Figure 1. The contribution of different iodine sources to the total iodine intake in children. Due to the possible influence of taking iodine oil pills, the data from Xinjiang were excluded, and the overall proportion was reanalyzed.
Factors MUIC (µg/L) Total iodine
intake (µg)Source of iodine Water Salt Processed foods iodine intake
(µg)Cooking food iodine intake (µg) MWIC (µg/L) Iodine Intake (µg) SIC (mg/kg) CRIS* (%) CRQIS† (%) Iodine Intake
(µg)Region Xinjiang 258.0
(179.1, 331.8)303.5
(210.9, 389.7)4.4
(2.1, 7.2)3.0
(0.9, 9.4)26.9 ± 4.0 100.0 92.9 295.4 ± 44.0 1.1
(0.5, 3.8)4.0
(−85.0, 92.6)Sichuan 249.9
(169.6, 360.8)294.0
(199.5, 424.5)1.9
(1.4, 3.3)1.3
(0.6, 4.1)27.2 ± 6.3 97.3 93.3 250.9 ± 58.3 4.9
(2.1, 11)36.9
(−84.1, 135.2)Shanxi 234.5
(129.2, 380.5)275.9
(152.0, 447.6)5.9
(3.6, 6.4)4.2
(2.0, 6.6)25.2 ± 4.9 98.5 93.3 203.9 ± 39.8 3.1
(1.3, 8.1)64.8
(−37.6, 283.8)Liaoning 204.0
(135.5, 286.4)240.0
(159.5, 336.9)9.4
(5.3, 13.2)6.6
(3.3, 9.4)23.7 ± 5.1 96.7 95.1 197.1 ± 42.4 2.6
(1.3, 7.0)33.8
(−45.4, 137.3)Fujian 213.7
(135.9, 310.2)251.4
(159.8, 364.9)3.2
(1.5, 3.6)2.3
(0.8, 4.4)21.7 ± 7.8 89.7 86.1 152.0 ± 54.4 6.1
(2.4, 12)91.0
(−21.2, 199.5)Anhui 247.2
(164.0, 328.1)290.8
(159.8, 364.9)2.1
(1.1, 3.1)1.5
(0.7, 3.8)23.1 ± 5.3 96.1 94.5 224.1 ± 51.2 5.5
(2.8, 9.0)59.7
(−58.9, 133.8)Hubei 251.7
(174.9, 350.0)296.1
(205.8, 411.8)2.6
(1.6, 3.0)1.8
(1.1, 2.8)25.9 ± 4.1 99.9 93.1 230.6 ± 36.4 6.7
(2.8, 17.1)57.0
(−52.8, 148.1)Economical level High 228.6
(150.5, 318.2)268.8
(177.0, 268.8)3.9
(1.9, 5.8)2.7
(1.3, 4.1)24.1 ± 6.6 95.0 90.8 234.2 ± 120.6 4.3
(1.5, 11.5)21.8
(−76.1, 141.9)Low 244.8
(159.7, 346.4)287.7
(187.1, 407.5)3.2
(1.6, 6.9)2.3
(1.1, 4.8)25.6 ± 4.8 98.7 94.4 244.8 ± 63.3 4.2
(1.7, 8.0)33.2
(−67.9, 153.2)Geographical features Mountain 247.1
(167.5, 331.3)290.5
(196.7, 389.5)1.8
(1.2, 3.6)1.3
(3.2, 4.2)26.7 ± 4.9 99.3 93.0 274.7 ± 91.5 4.0
(1.5, 7.9)2.2
(−93.6, 114.6)Plain 250.1
(163.0, 366.4)298.3
(200.0, 442.6)4.2
(2.5, 7.8)2.7
(1.9, 4.8)24.6 ± 5.3 97.5 93.8 253.1 ± 108.3 4.2
(1.3, 11.8)33.5
(−72.6, 175.5)Coastal 207.8
(131.5, 297.1)244.5
(154.7, 349.6)5.2
(4.6, 6.0)3.7
(3.2, 4.2)21.2 ± 8.0 88.2 84.7 165.2 ± 62.1 5.7
(1.8, 11.9)58.1
(−29.0, 179.2)inland 211.4
(138.6, 295.4)245.2
(159.1, 352.4)3.1
(1.7, 6.1)5.2
(1.1, 9.2)23.6 ± 5.1 98.0 96.3 203.4 ± 48.8 4.8
(1.9, 8.7)34.2
(−59.5, 148.4)Total 236.6
(155.6, 344.2)278.4
(183.0, 393.2)3.8
(7, 6.4)2.7
(1.1, 4.7)24.8 ± 5.8 96.9 92.6 220.5 ± 62.9 4.1
(1.5, 8.7)51.1
(−55.9.158.3)Excluding Xinjiang 232.6
(151.2, 335.0)273.7
(177.9, 394.1)3.8
(1.7, 6.3)2.7
(1.1, 4.4)24.5 ± 6.0 − − 209.1 ± 57.0 4.8
(1.9, 9.7)57.1
(−50.8, 169.5)Note. Results were presented as $ \stackrel{-}{x} $ ± s for normal distribution data and median (25th–75th) for skewed distribution data. MUIC, median urine iodine concentration; MWIC, median water iodine; SIC, salt iodine; CRIS, coverage rate of iodized salt, CRQIS, consumption rate of qualified iodized salt; *CRIS = number of salt samples with iodine content ≥ 5 mg/kg / number of samples tested ×100%; †CRQIS = number of salt sample with qualified iodine content / number of samples tested ×100% Table 2. Iodine intake from different sources
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As shown in Table 3, the overall MUIC of students was 236.6 (155.6–344.2) μg/L. Significant differences were observed in MUIC among the different regions (P < 0.001). The highest MUIC was Xinjiang (258.0 μg/L), and the lowest was Liaoning (204.0 μg/L). Boys had a significantly higher MUIC than girls (P < 0.001). The TVOL of 5,659 students showed a skewed distribution, and the median TVOL was 2.7 (IQR: 2.2–3.4) mL. The median TVOL was significantly different in children aged 8 (2.5, IQR: 2.0–3.1 mL), 9 (2.7, IQR: 2.2–3.4 mL), and 10 (3.0, IQR: 2.4–3.8 mL) years, which is normal according to the natural growth law of adolescents. A total of 136 children with goiter were found in this survey, and the total GR (TGR) was 2.4% (the highest rate was 4.5% in Sichuan, and the lowest rate was 0.5% in Xinjiang). The TGR in children aged 8, 9, and 10 were 2.6%, 2.8%, and 1.9%, respectively. The total nodular detection rate was 11.5%. The rate of children with nodules varied in different regions, with the highest rate of 17.5% in Xinjiang and the lowest rate of 3.3% in Fujian. When the SIC, UIC, and TVOL of SAC in different regions were compared, the levels of SIC and UIC of SAC differed significantly, and the TVOL differed among 8, 9, and 10 years of age (F = 111.6; H = 106.7; H = 144.6, P < 0.001). According to the analysis of different economic conditions and geographical characteristics, the results were also different, showing that the SIC and UIC of children living in areas with low economic levels (SIC = 25.6 mg/kg; MUIC = 244.8 μg/L) were higher than with better economic levels (SIC = 24.1 mg/kg; MUIC = 228.6 μg/L), whereas, children living in coastal areas (TVOL = 3.0 mL) or areas with better economic levels (TVOL = 2.9 mL) had higher TVOL than children in other areas (TVOL = 2.7 mL in inland areas; 2.8 mL in plain areas; 2.6 mL in mountain areas) or in lower economic levels (TVOL = 2.6 mL). The detection rate of thyroid nodules was higher in areas with high economic levels than in areas with low economic levels (13.1% in high economic levels and 9.8% in low economic levels).
Factors Urine (n = 5, 664) Thyroid (n = 5, 659) n MUIC
(P25, P75,
µg/L)P value n TVOL
(P25, P75,
mL)TGR
(%)P value 8 9 10 n TVOL
(P25, P75, mL)TGR
(%)n TVOL
(P25, P75, mL)TGR
(%)n TVOL
(P25, P75, mL)TGR
(%)Region Xinjiang 804 258.0
(179.1, 331.8)0.001 803 2.0
(1.6, 2.6)0.5 0.001 227 1.8
(1.5, 2.2)0.4 337 2.1
(1.6, 2.6)0.6 233 2.3
(1.8, 3.0)0.4 Sichuan 805 249.9
(169.6, 360.8)805 3.3
(2.7, 3.9)4.5 312 3.0
(2.5, 3.6)4.8 288 3.4
(2.8, 4.0)3.8 205 3.7
(3.0, 4.3)4.9 Shanxi 819 234.5
(129.2, 380.5)813 3.0
(2.4, 3.8)3.1 151 2.6
(2.2, 3.4)4.0 304 2.8
(2.3, 3.6)3.6 326 3.3
(2.6, 4.0)2.1 Liaoning 800 204.0
(135.5, 286.4)800 3.0
(2.3, 3.6)2.8 226 2.8
(2.2, 3.3)2.7 369 2.9
(2.3, 3.5)3.1 215 3.3
(2.6, 4.0)2.3 Fujian 814 213.7
(135.9, 310.2)814 2.8
(2.3, 3.3)2.0 278 2.4
(2.1, 3.0)2.2 272 2.9
(2.4, 3.3)2.2 265 3.0
(2.6, 3.8)1.5 Anhui 798 247.2
(164.0, 328.1)800 2.8
(2.3, 3.5)2.8 247 2.5
(2.1, 3.0)2.8 280 2.9
(2.3, 3.6)4.3 273 3.1
(2.6, 3.8)1.1 Hubei 824 251.7
(174.9, 350.0)824 2.3
(1.8, 2.9)1.5 281 2.0
(1.6, 2.4)1.1 263 2.3
(1.9, 3.0)1.9 255 2.6
(2.0, 3.2)1.6 Gender Boys 2,801 241.1
(158.6, 337.1)0.001 2,811 2.8
(2.2, 3.4)2.0 0.001 869 2.5
(2.0, 3.1)2.4 1,020 2.8
(2.2, 3.4)2.1 887 3.0
(2.4, 3.7)1.7 Girls 2,842 216.1
(139.8, 316.7)2,850 2.7
(2.1, 3.5)2.8 855 2.4
(1.9, 3.1)2.9 1,081 2.7
(2.1, 3.4)3.4 886 3.1
(2.4, 3.8)2.1 Geographic area Urban 1,968 232.0
(155.8, 331.4)0.819 1,968 2.8
(2.2, 3.5)2.7% 0.349 590 2.5
(2.0, 3.1)3.4% 776 2.8
(2.2, 3.4)2.7% 582 3.1
(2.4, 3.9)2.1% Rural 3,965 240.1
(155.5, 335.4)3,699 2.8
(2.2, 3.6)7.0% 1132 2.5
(2.0, 3.2)8.9% 1,325 2.8
(2.1, 3.5)6.0% 1,191 3.1
(2.4, 4.0)6.0% Economical level High 2,806 228.6
(150.5, 318.2)0.001 2,796 2.9
(2.3, 3.5)3.1 0.001 846 2.6
(2, 0, 3.2)3.4 1,065 2.8
(2.2, 3.4)3.4 863 3.2
(2.6, 3.9)2.4 Low 2,858 244.8
(159.7, 346.4)2,863 2.6
(2.1, 3.3)1.8 875 2.4
(1.9, 3.0)1.7 1,030 2.6
(2.1, 3.4)2.1 909 2.9
(2.2, 3.7)1.4 Geographical features Mountain 2,026 247.1
(167.5, 331.3)0.001 2,026 2.6
(2.0, 3.3)1.7 0.001 594 2.4
(1.8, 2.9)1.7 807 2.5
(2.0, 3.2)2.1 607 2.8
(2.2, 3.6)1.3 Plain 2,024 250.1
(163.0, 366.4)2,019 2.8
(2.2, 3.6)3.2 623 2.5
(2.0, 3.2)3.5 657 2.9
(2.1, 3.6)3.6 799 3.2
(2.5, 3.8)2.5 Coastal 800 207.8
(131.5, 297.1)800 3.0
(2.4, 3.7)3.1 265 2.7
(2.1, 3.4)2.6 264 3.0
(2.5, 3.6)4.2 271 3.3
(2.8, 4.1)2.6 inland 814 211.4
(138.6, 295.4)814 2.7
(2.3, 3.3)1.6 239 2.5
(2.0, 2.9)2.1 367 2.8
(2.3, 3.4)1.6 209 3.0
(2.4, 3.7)1.0 Total 5,664 236.6
(155.6, 344.2)5,659 2.7
(2.2, 3.4)2.4 1,722 2.5
(2.0, 3.1)2.6 2,103 2.7
(2.2, 3.4)2.8 1,722 3.0
(2.4, 3.8)1.9 Note. Wilcoxon test was used to compare UIC and TVOL between genders, geographic area and economical level. Kruskal–Wallis test was used to compare UIC and TVOL among region and geographical features. P < 0.05 was considered statistically significant. MUIC, median of urine iodine concentration; TVOL, thyroid volume; TGR, thyroid goiter rate. Table 3. Iodine nutrition status, TVOL, and GR of SAC
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In Table 4, the effects of various iodine sources on iodine nutritional status and thyroid goiter and nodules in SAC were analyzed. The SIC correlated with UIC and TVOL (r = 0.999 and −0.933, respectively, P < 0.05), iodine intake from processed foods also showed a weak correlation with the TVOL (r = 0.080, P < 0.01). There was no significant correlation between other iodine sources and iodine nutritional status and between thyroid goiter and nodule in SAC. In Supplementary Table S2 (available in www.besjournal.com), the effects of various iodine sources on iodine nutritional status in children were analyzed by multiple linear regressions. Iodine from iodized salt and cooked food was significantly associated with UIC in children. The UIC increases with the iodine from salt (P < 0.001) and cooked foods (P < 0.001). After stratification by gender, age, and geographic area, trends also persisted. A significant positive correlation was found between iodine obtained from iodized salt and the TVOL at the total level (P = 0.033) and after controlling for age (P = 0.031 at 8 years, P = 0.040 at 9 years, and P = 0.047 at 10 years). In Supplementary Table S3 (available in www.besjournal.com), the effects of various iodine sources on thyroid disease were analyzed by binary logistic regression. The results showed that the iodine obtained from iodized salt was negatively related to thyroid goiter (P = 0.004, OR = 0.997, 95% CI = 0.994, 0.999). So, the iodine from iodized salt is a protective factor for thyroid goiter. The iodine from water and iodine-rich processed foods were related to thyroid nodules (water: P < 0.001, OR = 0.983, 95% CI = 0.974, 0.992; iodine-rich processed foods: P = 0.001, OR = 1.053, 95% CI = 1.022, 1.085). Therefore, we maintain that iodine from water is a protective factor, and iodine from iodine-rich processed food is a risk factor for thyroid nodules.
Iodine resource UIC (µg/L) TVOL (mL) TGR (%) Nodular detection rate (%) r P value r P value r P value r P value WIC −0.151 0.443 0.066 0.740 0.137 0.486 0.036 0.859 SIC 0.999* < 0.001 −0.933* 0.021 −0.272 0.162 − − Processed food iodine 0.001 0.940 0.080* < 0.001 0.074 0.720 −0.288 0.163 Cooking food iodine 0.205 0.296 0.197 0.315 −0.279 0.150 0.135 0.503 Note. UIC, urine iodine concentration; TVOL, thyroid volume; TGR, thyroid goiter rate; WIC, water iodine concentration; SIC, salt iodine concentration; *Correlation analysis was used to describe correlations between different variables. P < 0.05 was considered significant. Table 4. The influence of iodine intake from different source on iodine nutrition status and thyroid disease
Indicators
Iodine intakeUIC (µg/L) TVOL (mL) β t P value β t P value Genders Boys WIC 0.069 0.848 0.405 0.032 0.157 0.876 SIC 0.752 8.528 < 0.001 −0.025 −0.114 0.911 Processed food iodine 0.046 0.573 0.572 0.172 0.862 0.397 Cooking food iodine 0.903 10.249 < 0.001 0.236 1.087 0.288 Girls WIC −0.009 −0.096 0.924 −0.038 −0.217 0.830 SIC 0.774 7.470 < 0.001 −0.428 −2.208 0.037 Processed food iodine 0.071 0.763 0.453 0.083 0.476 0.638 Cooking food iodine 0.917 8.796 < 0.001 0.221 1.134 0.269 Geographic area Urban WIC −0.360 −1.044 0.317 0.095 0.278 0.786 SIC 0.854 2.344 0.037 −0.588 −1.626 0.130 Processed food iodine 0.696 1.588 0.138 0.124 0.284 0.781 Cooking food iodine 0.277 0.893 0.389 −0.083 −0.271 0.791 Rural WIC −0.004 −0.042 0.967 0.013 0.060 0.953 SIC 0.727 7.384 < 0.001 −0.479 −2.123 0.050 Processed food iodine 0.040 0.431 0.672 0.114 0.538 0.598 Cooking food iodine 0.922 9.107 < 0.001 0.139 0.599 0.557 Ages (years) 8 WIC 0.152 1.302 0.206 −0.134 −0.717 0.480 SIC 0.729 5.905 < 0.001 −0.454 −2.302 0.031 Processed food iodine 0.005 0.040 0.968 0.118 0.643 0.526 Cooking food iodine 0.719 5.816 < 0.001 0.056 0.282 0.781 9 WIC 0.040 0.335 0.741 0.043 0.248 0.806 SIC 0.727 5.483 < 0.001 −0.411 −2.175 0.040 Processed food iodine 0.140 1.180 0.250 0.114 0.673 0.507 Cooking food iodine 0.845 6.395 < 0.001 0.278 1.477 0.153 10 WIC 0.020 0.179 0.860 −0.087 −0.488 0.630 SIC 0.803 6.330 < 0.001 −0.435 −2.108 0.047 Processed food iodine 0.278 2.416 0.024 0.101 0.538 0.596 Cooking food iodine 0.899 7.171 < 0.001 0.168 0.824 0.419 Total WIC 0.037 0.461 0.649 −0.039 −0.225 0.824 SIC 0.782 8.992 < 0.001 −0.432 −2.265 0.033 Processed food iodine 0.064 0.811 0.425 0.103 0.593 0.559 Cooking food iodine 0.927 10.635 < 0.001 0.224 1.172 0.253 Note. UIC, urine iodine concentration; TVOL, thyroid volume; WIC, water iodine concentration; SIC, salt iodine concentration. Table S2. Effect of iodine source on iodine nutritional status of SAC
Indicators Iodine intake† TGR Nodular detection rate (%) β OR 95% CI P value β OR 95% CI P value Genders Boys WIC 0.004 1.004 0.994 1.014 0.479 −0.021 0.979 0.965 0.994 0.005 SIC −0.001 0.999 0.995 1.002 0.484 0.001 1.001 1.000 1.002 0.184 Processed food iodine 0.008 1.008 0.919 1.106 0.866 0.037 1.038 0.992 1.085 0.105 Cooking food iodine 0.001 1.001 1.000 1.002 0.173 0.000 1.000 0.999 1.000 0.447 Girls WIC −0.003 0.997 0.985 1.010 0.656 −0.014 0.986 0.975 0.997 0.016 SIC −0.005 0.995 0.992 0.998 0.001 0.000 1.000 0.999 1.002 0.523 Processed food iodine −0.046 0.955 0.876 1.042 0.299 0.064 1.066 1.023 1.110 0.002 Cooking food iodine −0.001 0.999 0.998 1.001 0.275 0.000 1.000 0.999 1.001 0.902 Geographic area Urban WIC 0.003 1.003 0.990 1.015 0.670 −0.014 0.986 0.975 0.997 0.016 SIC −0.003 0.997 0.993 1.001 0.185 0.000 1.000 0.999 1.002 0.523 Processed food iodine −0.101 0.904 0.802 1.019 0.100 0.064 1.066 1.023 1.110 0.002 Cooking food iodine 0.000 1.000 0.998 1.001 0.840 0.000 1.000 0.999 1.001 0.902 Rural WIC 0.000 1.000 0.990 1.010 0.987 −0.023 0.977 0.965 0.990 < 0.001 SIC −0.003 0.997 0.994 1.000 0.023 0.001 1.001 1.000 1.002 0.113 Processed food iodine 0.018 1.018 0.942 1.101 0.648 −0.002 0.998 0.958 1.040 0.923 Cooking food iodine 0.000 1.000 0.999 1.001 0.996 0.000 1.000 1.000 1.001 0.889 Ages (years) 8 WIC −0.001 0.999 0.983 1.015 0.906 −0.028 0.972 0.951 0.994 0.012 SIC −0.002 0.998 0.994 1.002 0.262 0.001 1.001 0.999 1.002 0.409 Processed food iodine −0.011 0.989 0.885 1.106 0.847 0.045 1.046 0.986 1.109 0.139 Cooking food iodine 0.001 1.001 0.999 1.002 0.314 0.000 1.000 0.999 1.001 0.941 9 WIC 0.003 1.003 0.994 1.012 0.534 −0.014 0.986 0.972 0.999 0.038 SIC −0.003 0.997 0.993 1.001 0.115 0.001 1.001 1.000 1.002 0.211 Processed food iodine −0.035 0.966 0.881 1.059 0.455 0.070 1.072 1.027 1.120 0.002 Cooking food iodine 0.000 1.000 0.998 1.001 0.774 0.000 1.000 0.999 1.001 0.671 10 WIC −0.006 0.994 0.971 1.018 0.640 −0.012 0.988 0.974 1.002 0.083 SIC −0.005 0.995 0.991 0.999 0.022 0.000 1.000 0.999 1.002 0.733 Processed food iodine 0.003 1.003 0.876 1.148 0.964 0.024 1.024 0.965 1.088 0.431 Cooking food iodine 0.000 1.000 0.998 1.001 0.731 −0.001 0.999 0.999 1.000 0.258 Total WIC 0.001 1.001 0.993 1.009 0.896 −0.017 0.983 0.974 0.992 < 0.001 SIC −0.003 0.997 0.994 0.999 0.004 0.001 1.001 1.000 1.001 0.185 Processed food iodine −0.020 0.980 0.920 1.044 0.535 0.051 1.053 1.022 1.085 0.001 Cooking food iodine 0.000 1.000 0.999 1.001 0.996 0.000 1.000 0.999 1.000 0.461 Note. TGR, thyroid goiter rate; WIC, water iodine concentration; SIC, salt iodine concentration. Table S3. Effect of iodine source on thyroid disease of SAC
Based on UIC, we calculated the children’s total iodine intake. Then, based on the frequency of processed foods, the amount of intake, and the iodine content of processed foods, we calculated the iodine intake of children through processed foods. We assumed that processed foods do not contain iodine, i.e., based on the presumption that all iodine in processed food comes from iodized salt during production and not from the food. Then, we recalculated the total iodine intake and compared its effect on UIC in children. As shown in Supplementary Table S4 (available in www.besjournal.com), when the processed food was presumed to be produced without using iodized salt, the proposed MUIC of SAC was lower than that in SAC when it was using iodized salt. However, the proposed MUIC was higher than 200 µg/L for all provinces except Liaoning (197.2 µg/L). We compared the effect on UIC when SAC ate out using non-iodized salt, and the results showed a significant difference. The proposed MUIC was 100–200 µg/L in all provinces except Xinjiang (213.0 µg/L) and Shanxi (200.9 µg/L).
Indicators Iodized salt
for processed
foodsProposed
non-iodized
salt for
processed
foodsz P Iodized salt
for dining outProposed
non-iodized
salt for dining
outz P Total
iodine
intakeMUIC Total
iodine
intakeMUIC Total
iodine
intakeMUIC Total
iodine
intakeMUIC Region Xinjiang 303.5 258.0 301.4 256.2 −23.935 < 0.001 303.5 258.0 250.6 213.0 −14.374 < 0.001 Sichuan 294.0 249.9 284.2 241.2 −24.579 < 0.001 294.0 249.9 175.2 148.9 −24.318 < 0.001 Shanxi 275.9 234.5 268.8 226 −24.791 < 0.001 274.9 234.5 236.3 200.9 −16.328 < 0.001 Liaoning 240.0 204.0 232.8 197.2 −24.090 < 0.001 240.0 204.0 176.9 150.4 −24.407 < 0.001 Fujian 251.4 213.7 239.5 203.9 −24.716 < 0.001 250.9 213.7 226.7 192.7 −13.0 < 0.001 Anhui 290.8 247.2 283.6 241.3 −24.457 < 0.001 290.5 247.2 213.7 181.7 −21.986 < 0.001 Hubei 296.1 251.7 273.8 234.4 −24.822 < 0.001 296.2 251.7 187.2 159.1 −23.757 < 0.001 Genders Boys 290.8 247.2 282.9 240.5 −45.576 < 0.001 290.7 247.2 215.5 183.2 −40.677 < 0.001 Girls 263.9 224.3 253.9 215.8 −46.018 < 0.001 263.5 224.3 200.6 170.5 −40.790 < 0.001 Age (years) 8 263.6 224.0 253.7 215.6 −35.586 < 0.001 263.1 224.0 196.7 167.2 −31.716 < 0.001 9 277.7 236.1 268.3 228.1 −39.454 < 0.001 277.6 236.1 213.6 181.6 −34.836 < 0.001 10 288.8 245.5 278.6 236.8 −36.306 < 0.001 288.7 245.5 210.0 178.5 −32.317 < 0.001 Geographic area Urban 273.1 232.2 263.2 223.7 −38.267 < 0.001 273.1 232.2 216.9 184.4 −33.135 < 0.001 Rural 282.5 240.1 271.7 230.9 −52.253 < 0.001 281.8 240.1 202.7 172.3 −47.121 < 0.001 Economical level High 268.9 228.6 255.1 216.8 −45.535 < 0.001 268.9 228.6 207.9 176.7 −39.588 < 0.001 Low 288.0 244.8 281.3 239.1 −46.059 < 0.001 287.7 244.8 209.9 178.4 −41.854 < 0.001 Geographical features Mountain 290.8 247.1 283.0 240.6 −38.919 < 0.001 290.5 247.1 205.4 174.6 −34.095 < 0.001 Plain 298.5 253.7 287.0 243.9 −36.604 < 0.001 298.4 253.7 221.9 188.6 −33.398 < 0.001 Coastal 244.5 207.8 233.0 198.1 −24.090 < 0.001 244.5 207.8 194.7 165.5 −22.075 < 0.001 Inland 245.3 208.5 240.1 204.1 −27.584 < 0.001 245.2 208.5 204.5 173.5 −22.621 < 0.001 Total 278.4 236.6 268.0 228.4 −64764 < 0.001 278.2 236.6 209.2 177.8 −57.606 < 0.001 Note. MUIC, median of urine iodine concentration. Table S4. Effects of using non-iodized salt for processed foods or eating out on urinary iodine in children
Through the questionnaire survey of the favorite snacks of SAC in each region, 16 favorite foods were found, including 1) puffed food, 2) candy, 3) dim sum, 4) cookies, 5) spicy strips, 6) chocolate, 7) instant noodles, 8) fruits, 9) seaweed, 10) dairy products, 11) drinks, 12) ice cream, 13) salty dried nuts, 14) jelly, 15) ham sausage, and 16) preserved fruit. In addition, two-thirds of them were iodine-rich processed foods, as shown in Supplementary Figure S1 (available in www.besjournal.com).
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Dining Place Analysis in Children
Iodine Source Analysis
Iodine Nutrition Status of SAC
Influence of Iodine Source on Iodine Nutrition Status and Thyroid Goiter and Nodule
22071Supplementary Materials.pdf |