Juanjuan Zhang1, Yeqing Gu2, Ge Meng3,4, Qing Zhang5, Li Liu5, Hongmei Wu1, Shunming Zhang1, Yawen Wang1, Tingjing Zhang1, Xuena Wang1, Xu Zhang1, Xing Wang5, Shaomei Sun5, Ming Zhou5, Qiyu Jia5, Kun Song5, Kaijun Niu6,7,8,9,10. 1. Nutritional Epidemiology Institute and School of Public Health, Tianjin Medical University, Tianjin, China. 2. Institute of Radiation Medicine, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin, China. 3. Nutritional Epidemiology Institute and School of Public Health, Tianjin Medical University, Tianjin, China. mengge@tmu.edu.cn. 4. Department of Toxicology and Sanitary Chemistry, School of Public Health, Tianjin Medical University, Tianjin, China. mengge@tmu.edu.cn. 5. Health Management Centre, Tianjin Medical University General Hospital, Tianjin, China. 6. Nutritional Epidemiology Institute and School of Public Health, Tianjin Medical University, Tianjin, China. nkj0809@gmail.com. 7. Institute of Radiation Medicine, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin, China. nkj0809@gmail.com. 8. Health Management Centre, Tianjin Medical University General Hospital, Tianjin, China. nkj0809@gmail.com. 9. Tianjin Key Laboratory of Environment, Nutrition and Public Health, Tianjin, China. nkj0809@gmail.com. 10. Center for International Collaborative Research on Environment, Nutrition and Public Health, Tianjin, China. nkj0809@gmail.com.
Abstract
PURPOSE: The protective effect of onion against thyroid hypofunction has been reported in animal studies. However, in humans, the association between onion consumption and subclinical hypothyroidism (SCH) are unclear. The study sought to explore the association between habitual onion intake and SCH among adult population from an iodine-replete area. METHODS: A cross-sectional study (6515 men and 5290 women) was performed in Tianjin, China. Frequency of onion consumption was assessed using a valid self-administered food frequency questionnaire. Serum free triiodothyronine (FT3), free thyroxine (FT4), and thyroid-stimulating hormone (TSH) were determined by chemiluminescence immunoassay. SCH was diagnosed with TSH > 4.78 mIU/L. Multiple logistic regression was used to evaluate the association of onion intake with SCH. RESULTS: The prevalence of SCH was 2.56% in men and 7.18% in women, respectively. In women, the fully adjusted odds ratios [95% confidence interval (CI)] of having SCH across increasing frequency of onion intake were 1.00 (reference) for <1 time/week, 0.99 (0.73, 1.34) for 1-3 times/week, 0.74 (0.53, 1.03) for 4-6 times/week, and 0.67 (0.47, 0.97) for ≥7 times/week (P for trend <0.01). However, we observed no significant association between onion intake and SCH in men. Stratified analyses suggested a potential effect modification by age: the odds ratios (95% CI) across extreme quartiles was 0.37 (0.17, 0.80) in <40 women and 1.11 (0.51, 2.47) in >60 women. CONCLUSIONS: Frequent consumption of onion is inversely associated with SCH in adult women from an iodine-replete area. Further studies are needed to explore the casual relationship. TRIAL REGISTRATION WEBSITE: https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000031137.
PURPOSE: The protective effect of onion against thyroid hypofunction has been reported in animal studies. However, in humans, the association between onion consumption and subclinical hypothyroidism (SCH) are unclear. The study sought to explore the association between habitual onion intake and SCH among adult population from an iodine-replete area. METHODS: A cross-sectional study (6515 men and 5290 women) was performed in Tianjin, China. Frequency of onion consumption was assessed using a valid self-administered food frequency questionnaire. Serum free triiodothyronine (FT3), free thyroxine (FT4), and thyroid-stimulating hormone (TSH) were determined by chemiluminescence immunoassay. SCH was diagnosed with TSH > 4.78 mIU/L. Multiple logistic regression was used to evaluate the association of onion intake with SCH. RESULTS: The prevalence of SCH was 2.56% in men and 7.18% in women, respectively. In women, the fully adjusted odds ratios [95% confidence interval (CI)] of having SCH across increasing frequency of onion intake were 1.00 (reference) for <1 time/week, 0.99 (0.73, 1.34) for 1-3 times/week, 0.74 (0.53, 1.03) for 4-6 times/week, and 0.67 (0.47, 0.97) for ≥7 times/week (P for trend <0.01). However, we observed no significant association between onion intake and SCH in men. Stratified analyses suggested a potential effect modification by age: the odds ratios (95% CI) across extreme quartiles was 0.37 (0.17, 0.80) in <40 women and 1.11 (0.51, 2.47) in >60 women. CONCLUSIONS: Frequent consumption of onion is inversely associated with SCH in adult women from an iodine-replete area. Further studies are needed to explore the casual relationship. TRIAL REGISTRATION WEBSITE: https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000031137.