Association between lifestyle factors and thyroid function in young euthyroid adults

Abstract

<p><strong>Purpose:</strong><br></p><p>The present work examines the associations of dietary habits, sedentarism, physical activity (PA) levels and sleep habits, with thyroid function in young euthyroid adults.</p><p><strong>Methods:</strong></p><p>A total of 105 young euthyroid adults participated in this cross-sectional study. Thyroid function was determined in fasting conditions (> 6 h). Dietary habits were measured by a food frequency questionnaire and three non-consecutive 24 h recalls, and different dietary intake and patterns were then estimated. The time spent in sedentary, PA levels and sleep habits were objectively measured using a wrist-worn accelerometer.</p><p><strong>Results: </strong></p><p>Energy and carbohydrate intake were positively associated with thyroid stimulating hormone (TSH) (<em>β</em> = 0.222; <em>R</em>² = 0.102; <em>P</em> = 0.022 and <em>β</em> = 0.425; <em>R</em>² = 0.129; <em>P</em> = 0.007 , respectively) whereas fat intake was negatively associated with TSH (<em>β</em> = −0.428; <em>R²</em> = 0.137; <em>P</em> = 0.004). Energy intake was also positively associated with free triiodothyronine (<em>β</em> = 0.277; <em>R²</em> = 0.137; <em>P</em> = 0.004). Further, adherence to the Mediterranean diet was negatively related to TSH and free thyroxine (FT4) (<em>β</em> = −0.221; <em>R</em>² = 0.113; <em>P</em> = 0.020 and <em>β</em> = −0.268; <em>R</em>² = 0.071; <em>P</em> = 0.007, respectively). Vigorous-intensity and overall PA were negatively associated with FT4 (<em>β</em> = −0.227; <em>R</em>² = 0.052; <em>P</em> = 0.022 and <em>β</em> = −0.204; <em>R</em>² = 0.042; <em>P</em> = 0.041, respectively). In contrast, no associations were found between sleep parameters and thyroid function.</p><p><strong>Conclusions:</strong></p><p>Lifestyle factors such as dietary intake and PA levels seems to be related to thyroid function even in young euthyroid adults.</p>