The Effect of High Dose Isoflavone Supplementation on Serum Reverse T3 in Euthyroid Men With Type 2 Diabetes and Post-menopausal Women
<h3>Background</h3><p dir="ltr">The health benefits of soy are widely reported but there are queries on the effect of soy isoflavones on thyroid function and the underlying mechanism of action.</p><h3>Materials and Methods</h3><p dir="ltr"&g...
محفوظ في:
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| مؤلفون آخرون: | , , , , , |
| منشور في: |
2018
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| الوسوم: |
إضافة وسم
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| الملخص: | <h3>Background</h3><p dir="ltr">The health benefits of soy are widely reported but there are queries on the effect of soy isoflavones on thyroid function and the underlying mechanism of action.</p><h3>Materials and Methods</h3><p dir="ltr"> We examined the effect of soy isoflavones on reverse tri-iodothyronine (or 3,3′,5′-tri-iodothyronine; rT<sub>3</sub>) in two studies comprising 400 patients: 200 men (study 1; 3 months) and 200 post-menopausal women (study 2; 6 months) who were randomized to consume 15 g soy protein with 66 mg of isoflavones (SPI) daily, or 15 g soy protein alone without isoflavones (SP) daily.</p><h3>Results</h3><p dir="ltr">SPI supplementation increased rT<sub>3</sub> serum concentration in both men 0.41 (0.12) vs. 0.45 (0.14) nmol/L and women 0.33 (0.12) vs. 0.37 (0.09) nmol/L at 3 months compared to SP that was not seen at 6 months. Thyroid stimulating hormone (TSH) serum concentrations increased while free thyroxine (fT<sub>4</sub>) concentrations decreased with 3 months of SPI compared to SP supplementation for both men and women. rT<sub>3</sub> correlated with TSH in both studies (<i>p</i> = 0.03) but not with either fT<sub>3</sub> or fT<sub>4</sub>. fT<sub>3</sub> levels did not differ between the SPI and SP preparations.</p><h3>Conclusion</h3><p dir="ltr">Soy isoflavones transiently increased rT3 levels within 3 months though reverted to baseline at 6 months. The mechanism for this would be either rT3 degrading deiodinase 1 and/or deiodinase 2 activities are transiently inhibited at 3 months, or inhibition of deiodinase 3, which generates rT3 from T4 is induced at 6 months. These changes were mirrored in the TSH concentrations, suggesting that short-term high dose isoflavone transiently impairs thyroid function in the first 3 months and may impact on general health during this period.</p><p dir="ltr"><b>ISRCTN Registry:</b> ISRCTN 90604927; ISRCTN34051237.</p><h2>Other Information</h2><p dir="ltr">Published in: Frontiers in Endocrinology<br>License: <a href="https://creativecommons.org/licenses/by/4.0/" target="_blank">https://creativecommons.org/licenses/by/4.0/</a><br>See article on publisher's website: <a href="https://dx.doi.org/10.3389/fendo.2018.00698" target="_blank">https://dx.doi.org/10.3389/fendo.2018.00698</a></p> |
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