Low selenium status is associated with increased risk of thyroid disease. - GreenMedInfo Summary
Low population selenium status is associated with increased prevalence of thyroid disease.
J Clin Endocrinol Metab. 2015 Aug 25:jc20152222. Epub 2015 Aug 25. PMID: 26305620
CONTEXT: Epidemiological studies have supported the premise that an adequate selenium intake is essential for thyroid-gland function Objective: To investigate whether the prevalence of thyroid disease differed in two areas, similar except for very different soil/crop selenium concentrations.
DESIGN: Cross-sectional observational study.
SETTING: Two counties of Shaanxi Province, China, here defined as adequate- and low-selenium.
PARTICIPANTS: 6152 participants selected by stratified cluster-sampling.
MAIN OUTCOME MEASURES: Participants completed demographic and dietary questionnaires and underwent physical and thyroid-ultrasound examinations. Serum samples were analysed for thyroid-function parameters and selenium concentration. Serum selenium was compared between different demographic, dietary and lifestyle categories in the two counties. The relationship between selenium status, dietary factors and pathological thyroid conditions was explored by logistic regression.
RESULTS: Complete data sets were available from 3,038 adequate-selenium and 3,114 low-selenium participants in whom median (IQR) selenium concentrations differed almost two-fold [103.6 (79.7, 135.9) vs. 57.4 (39.4, 82.1)μg/L; P=0.001]. The prevalence of pathological thyroid conditions (hypothyroidism, subclinical hypothyroidism, autoimmune thyroiditis, enlarged thyroid) was significantly lower in the adequate-selenium than in the low-selenium county (18.0% vs. 30.5%; P<0.001). Higher serum selenium was associated with lower odds (OR; 95% CI) of autoimmune thyroiditis (0.47; 0.35, 0.65), subclinical hypothyroidism (0.68; 0.58, 0.93), hypothyroidism (0.75; 0.63, 0.90) and an enlarged thyroid (0.75; 0.59, 0.97).
CONCLUSIONS: Low selenium status is associated with increased risk of thyroid disease. Increased selenium intake may reduce the risk in areas of low selenium intake which exist not only in China but in many other parts of the world.