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Effect of probiotics or prebiotics on thyroid function: A meta-analysis of eight randomized controlled trials.
Shu, Q, Kang, C, Li, J, Hou, Z, Xiong, M, Wang, X, Peng, H
PloS one. 2024;19(1):e0296733
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The gut microbiome is thought to play a role in thyroid disorders, mediated by regulating iodine uptake, degradation and enterohepatic cycling of thyroid hormones, and differences in microbiome composition between patients with thyroid disorders and healthy individuals have been observed. The aim of this systematic review and meta-analysis was to evaluate the effect of pro-, pre- and synbiotics on thyroid function (thyroid stimulating hormone (TSH), free thyroxine (fT4) and free triiodothyronine (fT3) and thyroid stimulating hormone receptor antibody (TRAb)) in patients with and without thyroid disorders. 8 randomised controlled trials including 367 participants were included in the review and meta-analysis. Neither pro-, pre- nor synbiotics had a significant effect on TSH, fT4 or fT3 but pre- and probiotics lead to a significant reduction in TRAb in patients with Graves’ disease.
Abstract
BACKGROUND Microbiome-directed therapies are increasingly utilized to optimize thyroid function in both healthy individuals and those with thyroid disorders. However, recent doubts have been raised regarding the efficacy of probiotics, prebiotics, and synbiotics in improving thyroid function. This systematic review aimed to investigate the potential relationship between probiotics/prebiotics and thyroid function by analyzing the impact on thyroid hormone levels. METHODS We conducted a comprehensive systematic review and meta-analysis of randomized controlled trials that investigated the effects of probiotics, prebiotics, and synbiotics on free triiodothyronine (fT3), free thyroxine (fT4), thyroid stimulating hormone (TSH), and thyroid stimulating hormone receptor antibody (TRAb) levels. We searched for articles from PubMed, Scopus, Web of Science, and Embase up until April 1st, 2023, without any language restriction. Quantitative data analysis was performed using a random-effects model, with standardized mean difference (SMD) and 95% confidence interval as summary statistics. The methods and results were reported according to the PRISMA2020 statement. RESULTS A total of eight articles were included in this review. The meta-analysis showed no significant alterations in TSH (SMD: -0.01, 95% CI: -0.21, 0.20, P = 0.93; I2: 0.00%), fT4 (SMD: 0.04, 95% CI: -0.29, 0.21, P = 0.73; I2: 0.00%) or fT3 (SMD: 0.45, 95% CI: -0.14, 1.03, P = 0.43; I2: 78.00%), while a significant reduction in TRAb levels was observed (SMD: -0.85, 95% CI: -1.54, -0.15, P = 0.02; I2: 18.00%) following probiotics/prebiotics supplementation. No indication of publication bias was found. CONCLUSIONS Probiotics/prebiotics supplementation does not influence thyroid hormone levels, but may modestly reduce TRAb levels in patients with Graves' disease.
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Associations between Dynamic Vitamin D Level and Thyroid Function during Pregnancy.
Wang, H, Wang, HJ, Jiao, M, Han, N, Xu, J, Bao, H, Liu, Z, Ji, Y
Nutrients. 2022;14(18)
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Thyroid hormones play a vital role in regulating metabolism. Adequate thyroid hormone levels are also critical during pregnancy for optimal fetal growth and development. The foetus is dependent on maternal thyroid hormones until its own thyroid gland matured in the second half of pregnancy. Furthermore, pregnancy impacts thyroid function leading to an increased demand for thyroid hormones. Thyroid disease has been associated with Vitamin D deficiency. During pregnancy, both thyroid disorders and Vitamin D deficiency can have adverse effects on pregnancy and pregnancy outcomes, hence a potential link between Vitamin D status and thyroid function has been postulated. To fill the gaps in previous research, this retrospective cohort study aimed to explore the associations between Vitamin D status and thyroid function throughout the pregnancy, in each trimester. The analysis of hospital data collected in Beijing demonstrated an association between Vitamin D levels and thyroid function throughout pregnancy. Such interlink appeared to be dynamic and changed depending on the stage of pregnancy. The author's findings affirmed that maintenance of adequate Vitamin D levels supports normal thyroid function which is an important nutritional strategy for a healthy pregnancy.
Abstract
Optimal Vitamin D (VitD) status and thyroid function are essential for pregnant women. This study aimed to explore associations between dynamic VitD status and thyroid function parameters in each trimester and throughout the pregnancy period. Information on all 8828 eligible participants was extracted from the Peking University Retrospective Birth Cohort in Tongzhou. Dynamic VitD status was represented as a combination of deficiency/sufficiency in the first and second trimesters. Thyroid function was assessed in three trimesters. The associations between VitD and thyroid function were assessed by multiple linear regression and generalized estimating equation models in each trimester and throughout the pregnancy period, respectively. The results indicated that both free thyroxine (fT4; β = 0.004; 95%CI: 0.003, 0.006; p < 0.001) and free triiodothyronine (fT3; β = 0.009; 95%CI: 0.004, 0.015; p = 0.001) had positive associations with VitD status in the first trimester. A VitD status that was sufficient in the first trimester and deficient in the second trimester had a lower TSH (β = -0.370; 95%CI: -0.710, -0.031; p = 0.033) compared with the group with sufficient VitD for both first and second trimesters. In conclusion, the associations between VitD and thyroid parameters existed throughout the pregnancy. Maintaining an adequate concentration of VitD is critical to support optimal thyroid function during pregnancy.
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The correlation between selenium levels and autoimmune thyroid disease: a systematic review and meta-analysis.
Zuo, Y, Li, Y, Gu, X, Lei, Z
Annals of palliative medicine. 2021;10(4):4398-4408
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Autoimmune thyroid disease (AITD) encompasses several autoimmune conditions affecting the thyroid gland. Genetics, environmental and lifestyle factors influence the condition. Part of the clinical presentation is an abnormal function of the thyroid and the presence of antibodies against thyroid proteins, such as antithyroglobulin antibody (TGAb) and anti-thyroid peroxidase antibody (TPOAb). Selenium is a trace mineral essential to the human body and an important building block for a particular family of proteins called Selenoproteins. This protein family exerts enzymatic functions and plays a major role in thyroid health, furthermore, also in hormone synthesis and managing oxidative stress. Previous research noted that supplemental selenium had beneficial effects on thyroid hormones and antibodies. This systematic review and meta-analysis sought to collectively examine the effect of selenium supplementation on hormone and antibody levels in people with AITD. Blood values investigated were TSH (thyroid stimulating hormone), FT3 (free triiodothyronine), FT4 (Thyroxine), TPOAb, and TGAb. The review included 17 randomised controlled trials, with a total of 1,095 subjects with AITD, plus controls. The cumulated results demonstrated that selenium can notably decrease blood levels of FT3, FT4, and TPOAb in patients with AITD. However, levels of TSH and TGAb seemed not to be significantly affected by selenium supplementation. The authors highlighted that the review was not specific to a particular AITD and that there was limited literature available concerning TGAb levels. More research is needed to clarify the benefits of selenium in AITD.
Abstract
BACKGROUND This investigation systematically evaluated the selenium levels and the effects of selenium supplementation in patients with autoimmune thyroid disease (AITD). METHODS Randomized controlled trials (RCTs) related to selenium supplementation in patients with AITD were selected from the PubMed, Medline, Web of Sciences, Embase, Cochrane Library, and Spring databases. All related literature published between January 2000 and November 2020 were included. The RCT bias risk assessment was conducted according to the Cochrane Handbook 5.0.2. The Review Manager 5.3 software was applied for meta-analysis of the included literature. RESULTS A total of 17 articles meeting the requirements were selected, including a total of 1,911 subjects. Meta-analysis results showed that the serum free triiodothyronine (FT3) levels in patients was greatly reduced after selenium supplementation compared to placebo treatment (MD =-0.40; 95% confidential interval (CI): -0.70--0.10; Z=2.61; P=0.009). Serum free thyroxine (FT4) levels and anti-thyroid peroxidase antibody (TPOAb) levels were also significantly reduced (MD = -0.76; 95% CI: -1.58--0.07; Z=1.79; P=0.07), and anti-thyroid peroxidase antibody (TPOAb) level was decreased observably (MD =-150.25; 95% CI: -04.06--96.43; Z=5.47; P<0.00001). The thyroid stimulating hormone (TSH) levels (MD =0.06; 95% CI: -0.53-0.66; Z=0.21; P=0.83) and anti-thyroglobulin antibody (TGAb) levels (MD =17.19; 95% CI: -254.86-289.25; Z=0.12; P=0.90) were not significantly different between the experimental group and the control group. CONCLUSIONS Selenium-containing drugs were effective in treating AITD patients, and greatly reduced the levels of FT3, FT4, and TPOAb in AITD patients. These results suggested that selenium level had a great effect on AITD and selenium supplementation showed a very important effect on AITD.
