Evaluation of effect of isoflavone on thyroid economy & autoimmunity in oophorectomised women: a randomised, double-blind, placebo-controlled trial.
ABSTRACT 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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ABSTRACT: Soy isoflavones are commonly used to alleviate menopause-related symptoms. Postmenopausal women are at increased risk for hypothyroidism, and there are concerns that isoflavones may be detrimental to thyroid health. The aim of this study was to examine the effects of soy protein and isoflavones on thyroid function and the relationship between thyroid function and ovarian function. Adult female cynomolgus monkeys (Macaca fascicularis) were randomized to consume two diets differing only in protein source: casein-lactalbumin (n = 44) or soy protein with isoflavones (n = 41). After 34 months, all animals were ovariectomized via laparotomy. Half of the monkeys from each diet treatment group continued to consume their preovariectomy treatment phase diet (either isolated soy protein [n = 19] or casein-lactalbumin [n = 21]) for an additional 34 months. The remaining animals did not continue their diets and thus were not considered further. Circulating progesterone, triiodothyronine, thyroxine, and thyroid-stimulating hormone were measured at baseline. Thyroid hormones were remeasured during each treatment phase. Dietary soy increased triiodothyronine in preovariectomized monkeys and prevented a decline in thyroxine after surgical menopause (both P's < 0.05). Mean progesterone concentrations were positively correlated with triiodothyronine at baseline in preovariectomized monkeys (P < 0.01). Progesterone levels and triiodothyronine are positively correlated in macaques. Dietary soy increases triiodothyronine in preovariectomized monkeys and prevents a decline in thyroxine after surgical menopause. The outcomes observed in this study suggest that soy protein and isoflavone consumption does not adversely affect-and may even preserve-thyroid function in postmenopausal women.Menopause (New York, N.Y.) 03/2014; 21(10). DOI:10.1097/GME.0000000000000223 · 2.81 Impact Factor
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ABSTRACT: Genistein aglycone, one of the soy isoflavones, has been reported to be beneficial in the treatment of menopausal vasomotor symptoms, osteoporosis, and cardiovascular diseases, as well as in a variety of cancers. However, issues of potential harm on thyroid function resulting from soy isoflavones consumption have been raised. Much of the evidence for the goitrogenic effects of isoflavones is derived from experimental in vitro and in vivo studies. Goitrogenic effects were also noted in infants fed non-iodine-fortified, soy-based formula, a problem that was easily solved with iodine fortification. Recent studies suggest that genistein shows a good profile of safety on the thyroid although definitive conclusions have not reached. The aim of this brief review is to summarize and better clarify the effects of genistein on human thyroid health.Frontiers in Endocrinology 07/2012; 3:94. DOI:10.3389/fendo.2012.00094
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ABSTRACT: Background: Iodine requirements are increased during pregnancy to maintain maternal and fetal euthyroidism. There have been recent improvements in iodized salt coverage in India but whether iodized salt is enough to sustain iodine requirements during pregnancy providing adequate iodine to pregnant women remains uncertain. Our aims were to measure thyroid status in first trimester pregnant women in southern India and assess potential determinants of thyroid function, including iodine status, thyroid autoimmunity, dietary patterns, body weight and anemia. Methods: Cross-sectional study among 334 pregnant women ≤14 weeks of gestation, in Bangalore, India. We measured anthropometrics, urinary iodine concentration (UIC), maternal thyroid volume (by ultrasound) and thyroid function. We applied a TSH upper limit of 2.5 mIU/L to classify thyroid insufficiency. Using a questionnaire, we obtained socio-demographic and dietary data, obstetric history, and use of iodised salt and iodine supplements. Results: Among the women, mean (SD) gestational age was 10.3 (2.5) weeks, 67% were nulliparous, 21% were vegetarian, 19% were anemic and 23% were overweight or obese. Iodized salt was used by 98% of women and they were iodine sufficient: median UIC (range) was 184.2 (8.1-1152) µg/L median (range) UIC was 184 (97, 349) µg/L and all had normal thyroid volume. However, 18% of women had thyroid insufficiency: 3.7% had overt hypothyroidism (83% with positive TPO-Ab), 9.2% had subclinical hypothyroidism and 5.2% had hypothyroxinemia. Women consuming vegetarian diets did not have significantly lower iodine intakes or higher risk of hypothyroidism than those consuming mixed diets, but overweight/obesity and anemia predicted thyroid insufficiency. Conclusion: In this urban population of southern India, pregnant women have adequate iodine status in the first trimester. Despite this, many have thyroid insufficiency, and the prevalence of overt hypothyroidism is >5-fold higher than reported in other iodine-sufficient populations of pregnant women.Thyroid: official journal of the American Thyroid Association 06/2014; 24(9). DOI:10.1089/thy.2014.0071 · 3.84 Impact Factor