Evaluation of effect of isoflavone on thyroid economy & autoimmunity in oophorectomised women: A randomised, double-blind, placebo-controlled trial

Department of Pharmacology, Postgraduate Institute of Medical Education & Research, Chandigarh, India.
The Indian Journal of Medical Research (Impact Factor: 1.4). 06/2011; 133(6):633-40.
Source: PubMed


The potential of soy isoflavones to interfere with thyroid function has been reported. However, there are limited data regarding their effect on thyroid function and autoimmunity in surgical menopausal women. The present study aimed to evaluate the effect of isoflavones on thyroid function and autoimmunity, menopausal symptoms, serum follicle stimulating hormone (FSH) and estradiol levels in oophorectomised women.
A randomized, double blind, placebo-controlled trial was conducted in 43 oophorectomised women to evaluate the effect of soy isoflavones (75 mg/day for 12 wk) on serum thyroid profile (free T3, free T4, TSH, TBG and anti-TPO antibody titres) assessed at baseline, 6 and 12 wk after randomization. Assessment was also done for menopause symptom score (MSS) three weekly, and FSH and estradiol levels at baseline and at study completion.
There was a significant alteration in free T3 levels in the group receiving isoflavones (4.05 ± 0.36, 4.12 ± 0.69 and 3.76 ± 0.55 pmol/l at baseline, 6 and 12 wk, respectively; P=0.02). However, the mean change in various thyroid parameters at 12 wk from baseline was not significantly different between the two groups. MSS was also significantly decreased at 9 and 12 wk from baseline with isoflavones (12.47 ± 8.15, 9.35 ± 5.23 and 9 ± 5.14 at baseline, 9 and 12 wk respectively; P=0.004) with significant improvement in urogenital symptoms compared to placebo. Isoflavones did not significantly affect other parameters during study period. There were no serious adverse events reported and the proportion of patients experiencing adverse events was similar between the two groups.
Modest reduction in serum free T3 levels in the isoflavone group in the absence of any effect on other thyroid parameters might be considered clinically unimportant.

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    • "A 12-week duration randomized, double-blind and placebo-controlled trial in 43 oophorectomized Indian women, evaluated the effect of 75 mg/day soy isoflavones (genistein and genistin 25%; daidzein and daidzin 15%) on serum levels FT3, FT4, TSH, TBG, and anti-TPO antibodies (Mittal et al., 2011). The only variation found was a modest decrease in serum FT3. "
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