Causes of different goiter rates with the same iodine deficiency among the pastoral and agricultural populations of Tibet: a geographical comparison

Jing Xu; Shichuan Liu; Wei Ma; Xiuwei Li; Min Guo; Xiaoxiao Cao; Yunyou Gu; Haiyan Wang; Jianqiang Wang; Ying Zhang; Guangxiu Zhuang; Liejun Liu

doi:10.1186/s13044-022-00122-8

Causes of different goiter rates with the same iodine deficiency among the pastoral and agricultural populations of Tibet: a geographical comparison

Thyroid Res. 2022 Mar 19;15(1):4. doi: 10.1186/s13044-022-00122-8.

Authors

Jing Xu¹, Shichuan Liu^{1

2}, Wei Ma¹, Xiuwei Li¹, Min Guo³, Xiaoxiao Cao¹, Yunyou Gu¹, Haiyan Wang¹, Jianqiang Wang¹, Ying Zhang¹, Guangxiu Zhuang¹, Liejun Liu⁴

Affiliations

¹ Chinese Center for Disease Control and Prevention, Key Laboratory of Trace Element Nutrition of National Health Commission of China, National Institute for Nutrition and Health, 155 Changbai Road, Changping, Beijing, 102206, China.
² Hangzhou Center for Disease Control and Prevention, 568 Mingshi Road, Jianqiao Town, Hangzhou, 310021, Jianggan District, China.
³ Tibet Autonomous Region Center for Disease Control and Prevention, 71 Jinzhu Middle Road, Lhasa, 850002, China.
⁴ Chinese Center for Disease Control and Prevention, Key Laboratory of Trace Element Nutrition of National Health Commission of China, National Institute for Nutrition and Health, 155 Changbai Road, Changping, Beijing, 102206, China. liuliejun@icdc.cn.

Abstract

Background: The residents of both the agricultural and pastoral areas of Tibet share the same iodine deficiency and iodine nutrition, but the rate of thyroid goiter was significantly higher in the agricultural areas than in the pastoral areas. This project sought to determine why the populations in the iodine-deficient pastoral areas show a lower rate of thyroid goiter.

Methods: Food frequency questionnaires (FFQs) and 24 h history recalls were adopted to investigate the dietary patterns of the residents of the agricultural and pastoral areas. Meat and milk samples were collected to measure their inorganic iodine, total iodine and thyroid hormone contents using ICP-MS, As^III-Ce⁴⁺ catalytic spectrophotometry and the Siemens' chemiluminescence method, respectively. The intake of protein, and the microelements, selenium and iron, was calculated according to their content in the food.

Results: The per capita daily intake of meat, dairy, and cereal in the pastoral areas was 116.7, 216.7, and 433.3 g, respectively, which are significantly higher than those in the agricultural areas (50.0, 72.2, and 375.0 g, respectively) (p < 0.05). The content of thyroid hormone in dried beef and milk in the pastoral areas was 62.6 and 13.5 μg/kg, respectively, which was significantly higher than those in the agricultural areas (25.1 and 4.1 μg/kg, respectively) (p < 0.05). The daily intake of thyroid hormone, protein and microelements, selenium and iron from foods by the residents of the pastoral areas were 10.5 μg, 99.6 g, 30.0 μg and 15.8 mg respectively, which was significantly higher than those in the agricultural areas (1.79 μg, 56.5 g, 23.8 μg and 13.2 mg, respectively) (p < 0.05).

Conclusions: The significantly high intake of the food-borne thyroid hormone by the residents of the pastoral area could be the main reason the residents in the pastoral areas show a lower rate of thyroid goiter than those in the agricultural area. Moreover, the relatively high intake of protein and trace elements, selenium and iron by residents in the pastoral area could be another important factor for reducing the goiter rates.

Keywords: Iodine; Iodine deficiency; Thyroid goiter; Thyroid hormone; Tibet.