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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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Effects of Intermittent Energy Restriction Compared with Those of Continuous Energy Restriction on Body Composition and Cardiometabolic Risk Markers - A Systematic Review and Meta-Analysis of Randomized Controlled Trials in Adults.
Schroor, MM, Joris, PJ, Plat, J, Mensink, RP
Advances in nutrition (Bethesda, Md.). 2024;15(1):100130
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Intermittent energy restriction (IER) diets, such as the 5:2 diet, time-restricted eating (TRE), and alternate-day fasting (ADF), are gaining popularity. According to previous research, IER protocols effectively manage obesity and may have many other health benefits, including improving metabolic health. This systematic review and meta-analysis of twenty-eight parallel-design randomised controlled trials looked at the benefits of IER protocols, such as ADF, TRE, and the 5:2 diet, and the effects of continuous energy restriction (CER) on anthropometric and cardiometabolic outcomes. The results of this systematic review and meta-analysis showed that both the IER and CER are equally beneficial. However, IER protocols showed greater but clinically insignificant improvements in fat-free mass and waist circumference in healthy adults. IER and CER protocols were not different in improving the lipid profile, glucose and insulin levels and blood pressure. Different IER diets showed different positive effects on metabolic parameters. Future robust studies are required to assess the effects of these energy-restriction diets on metabolic and anthropometric parameters because of the high variability in the included studies. However, healthcare professionals can use the results of this review to understand the potential clinical utility of various energy-restriction diets.
Abstract
The interest in intermittent energy restriction (IER) diets as a weight-loss approach is increasing. Different IER protocols exist, including time-restricted eating (TRE), alternate-day fasting (ADF), and the 5:2 diet. This meta-analysis compared the effects of these IER diets with continuous energy restriction (CER) on anthropometrics and cardiometabolic risk markers in healthy adults. Twenty-eight trials were identified that studied TRE (k = 7), ADF (k = 10), or the 5:2 diet (k = 11) for 2-52 wk. Energy intakes between intervention groups within a study were comparable (17 trials), lower in IER (5 trials), or not reported (6 trials). Weighted mean differences (WMDs) were calculated using fixed- or random-effects models. Changes in body weight [WMD: -0.42 kg; 95% confidence interval (CI): -0.96 to 0.13; P = 0.132] and fat mass (FM) (WMD: -0.31 kg; 95% CI: -0.98 to 0.36; P = 0.362) were comparable when results of the 3 IER diets were combined and compared with those of CER. All IER diets combined reduced fat-free mass (WMD: -0.20 kg; 95% CI: -0.39 to -0.01; P = 0.044) and waist circumference (WMD: -0.91 cm; 95% CI: -1.76 to -0.06; P = 0.036) more than CER. Effects on body mass index [BMI (kg/m2)], glucose, insulin, homeostatic model assessment for insulin resistance (HOMA-IR), serum lipid and lipoprotein concentrations, and blood pressure did not differ. Further, TRE reduced body weight, FM, and fat-free mass more than CER, whereas ADF improved HOMA-IR more. BMI was reduced less in the 5:2 diet compared with CER. In conclusion, the 3 IER diets combined did not lead to superior improvements in anthropometrics and cardiometabolic risk markers compared with CER diets. Slightly greater reductions were, however, observed in fat-free mass and waist circumference. To what extent differences in energy intakes between groups within studies may have influenced these outcomes should be addressed in future studies.
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Effect of Calorie Restriction and Intermittent Fasting Regimens on Brain-Derived Neurotrophic Factor Levels and Cognitive Function in Humans: A Systematic Review.
Alkurd, R, Mahrous, L, Zeb, F, Khan, MA, Alhaj, H, Khraiwesh, HM, Faris, ME
Medicina (Kaunas, Lithuania). 2024;60(1)
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Brain-derived neurotrophic factor (BDNF) is a protein that plays a crucial role in brain development, cognition and metabolism. Intermittent fasting (IF) is a promising therapeutic strategy for managing metabolic disorders and improving cognitive function. Therefore, this systematic review of sixteen experimental and observational studies investigated the effect of IF on BDNF production and improvements in cognition through the BDNF pathway in healthy adults and people with metabolic disorders. Included studies focused on different IF regimens such as calorie restriction (CR), alternate-day fasting (ADF), time-restricted eating (TRE) and Ramadan model of intermittent fasting (RIF) Future, well-controlled, long-term, robust studies are required to assess the effect of different IF regimens on the production of BDNF and cognitive function in people with metabolic disorders, as the current research is inconclusive. However, healthcare professionals can use the review to understand the potential beneficial effects of IF on cognition and metabolic health in humans.
Abstract
Background: The potential positive interaction between intermittent fasting (IF) and brain-derived neurotrophic factor (BDNF) on cognitive function has been widely discussed. This systematic review tried to assess the efficacy of interventions with different IF regimens on BDNF levels and their association with cognitive functions in humans. Interventions with different forms of IF such as caloric restriction (CR), alternate-day fasting (ADF), time-restricted eating (TRE), and the Ramadan model of intermittent fasting (RIF) were targeted. Methods: A systematic review was conducted for experimental and observational studies on healthy people and patients with diseases published in EMBASE, Scopus, PubMed, and Google Scholar databases from January 2000 to December 2023. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis statements (PRISMA) for writing this review. Results: Sixteen research works conducted on healthy people and patients with metabolic disorders met the inclusion criteria for this systematic review. Five studies showed a significant increase in BDNF after the intervention, while five studies reported a significant decrease in BDNF levels, and the other six studies showed no significant changes in BDNF levels due to IF regimens. Moreover, five studies examined the RIF protocol, of which, three studies showed a significant reduction, while two showed a significant increase in BDNF levels, along with an improvement in cognitive function after RIF. Conclusions: The current findings suggest that IF has varying effects on BDNF levels and cognitive functions in healthy, overweight/obese individuals and patients with metabolic conditions. However, few human studies have shown that IF increases BDNF levels, with controversial results. In humans, IF has yet to be fully investigated in terms of its long-term effect on BDNF and cognitive functions. Large-scale, well-controlled studies with high-quality data are warranted to elucidate the impact of the IF regimens on BDNF levels and cognitive functions.
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Selenium Supplementation in Patients with Hashimoto Thyroiditis:A Systematic Review and Meta-Analysis of Randomized Clinical Trials.
Huwiler, VV, Maissen-Abgottspon, S, Stanga, Z, Mühlebach, S, Trepp, R, Bally, L, Bano, A
Thyroid : official journal of the American Thyroid Association. 2024
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Hashimoto Thyroiditis (HT) is a disease of the thyroid gland, which can result in insufficient production of thyroid hormone. Thyroid hormone is responsible for numerous functions within the body, such as weight regulation and energy production. Selenium is a nutrient that is used in the body to make thyroid hormones and low levels have been seen in patients with HT. Selenium supplementation has been researched previously, but inconsistent results have been shown. This systematic review and meta-analysis of 35 and 32 randomised control trials respectively, aimed to determine the effect of selenium supplementation on HT. The results showed that selenium supplementation favourably influenced thyroid hormones and oxidative stress, without affecting inflammation, but only if individuals were not receiving thyroid hormone replacement therapy. Adverse events were similar between the supplementation and control groups. It was concluded that selenium supplementation is a safe and effective therapy for individuals with HT who are not receiving hormone replacement therapy. This study could be used by healthcare professionals to recommend selenium supplementation as a way to balance thyroid hormones and alleviate the effects of HT.
Abstract
Background: Hashimoto thyroiditis (HT) is the most common cause of hypothyroidism in iodine-sufficient areas. Selenium is an essential trace element required for thyroid hormone synthesis and exerts antioxidant effects. Therefore, it may be of relevance in the management of HT. Methods: We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to evaluate the effect of selenium supplementation on thyroid function (thyrotropin [TSH], free and total thyroxine [fT4, T4], free and total triiodothyronine [fT3, T3]), thyroid antibodies (thyroid peroxidase antibodies [TPOAb], thyroglobulin antibodies [TGAb], thyrotropin receptor antibody [TRAb]), ultrasound findings (echogenicity, thyroid volume), immune markers, patient-reported outcomes, and adverse events in HT. The study protocol was registered on PROSPERO (CRD42022308377). We systematically searched MEDLINE, Embase, CINHAL, Web of Science, Google Scholar, and the Cochrane CENTRAL Register of Trials from inception to January 2023 and searched citations of eligible studies. Two independent authors reviewed and coded the identified literature. The primary outcome was TSH in patients without thyroid hormone replacement therapy (THRT); the others were considered secondary outcomes. We synthesized the results as standardized mean differences (SMD) or odds ratio (OR), assessed risk of bias using the Cochrane RoB 2 tool, and rated the evidence using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. Results: We screened 687 records and included 35 unique studies. Our meta-analysis found that selenium supplementation decreased TSH in patients without THRT (SMD -0.21 [confidence interval, CI -0.43 to -0.02]; 7 cohorts, 869 participants; I2 = 0%). In addition, TPOAb (SMD -0.96 [CI -1.36 to -0.56]; 29 cohorts; 2358 participants; I2 = 90%) and malondialdehyde (MDA; SMD -1.16 [CI -2.29 to -0.02]; 3 cohorts; 248 participants; I2 = 85%) decreased in patients with and without THRT. Adverse effects were comparable between the intervention and control groups (OR 0.89 [CI 0.46 to 1.75]; 16 cohorts; 1339 participants; I2 = 0%). No significant changes were observed in fT4, T4, fT3, T3, TGAb, thyroid volume, interleukin (IL)-2, and IL-10. Overall, certainty of evidence was moderate. Conclusions: In people with HT without THRT, selenium was effective and safe in lowering TSH, TPOAb, and MDA levels. Indications for lowering TPOAb were found independent of THRT.
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Incidence and Determinants of Spontaneous Normalization of Subclinical Hypothyroidism in Older Adults.
van der Spoel, E, van Vliet, NA, Poortvliet, RKE, Du Puy, RS, den Elzen, WPJ, Quinn, TJ, Stott, DJ, Sattar, N, Kearney, PM, Blum, MR, et al
The Journal of clinical endocrinology and metabolism. 2024;109(3):e1167-e1174
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With increasing age, circulating levels of thyroid stimulating hormone (TSH) generally rise, accompanied by a higher prevalence of subclinical hypothyroidism. Subclinical hypothyroidism is defined as an elevated TSH level while the serum free T4 (fT4) concentration is within the normal range. The aim of this study was to investigate the incidence of spontaneous normalisation of TSH levels and identify determinants of normalisation in a large group of adults aged 65 years and older with (persistent) subclinical hypothyroidism. This study was a longitudinal study that pooled data from 2 randomised, double-blind, placebo-controlled parallel-group clinical trials. Results showed that 60.8% of the older adults with biochemical subclinical hypothyroidism based on at least 1 elevated TSH measurement, TSH levels had returned to the normal range without intervention after a median follow-up of 1 year. Subsequently, TSH levels had still normalised after 1 year in 39.9% of older adults with persistent subclinical hypothyroidism. Younger age, female sex, lower initial TSH level, higher normal initial fT4 level, the absence of thyroid peroxidase antibodies, and a second measurement in summer were independent determinants for TSH normalisation. Authors concluded that since TSH levels spontaneously normalised in a large proportion of older adults with subclinical hypothyroidism, a third measurement is recommended before considering treatment.
Abstract
CONTEXT With age, the prevalence of subclinical hypothyroidism rises. However, incidence and determinants of spontaneous normalization remain largely unknown. OBJECTIVE To investigate incidence and determinants of spontaneous normalization of TSH levels in older adults with subclinical hypothyroidism. DESIGN Pooled data were used from the (1) pretrial population and (2) in-trial placebo group from 2 randomized, double-blind, placebo-controlled trials (Thyroid Hormone Replacement for Untreated Older Adults With Subclinical Hypothyroidism Trial and Institute for Evidence-Based Medicine in Old Age thyroid 80-plus thyroid trial). SETTING Community-dwelling 65+ adults with subclinical hypothyroidism from the Netherlands, Switzerland, Ireland, and the United Kingdom. PARTICIPANTS The pretrial population (N = 2335) consisted of older adults with biochemical subclinical hypothyroidism, defined as ≥1 elevated TSH measurement (≥4.60 mIU/L) and a free T4 within the laboratory-specific reference range. Individuals with persistent subclinical hypothyroidism, defined as ≥2 elevated TSH measurements ≥3 months apart, were randomized to levothyroxine/placebo, of which the in-trial placebo group (N = 361) was included. MAIN OUTCOME MEASURES Incidence of spontaneous normalization of TSH levels and associations between participant characteristics and normalization. RESULTS In the pretrial phase, TSH levels normalized in 60.8% of participants in a median follow-up of 1 year. In the in-trial phase, levels normalized in 39.9% of participants after 1 year of follow-up. Younger age, female sex, lower initial TSH level, higher initial free T4 level, absence of thyroid peroxidase antibodies, and a follow-up measurement in summer were independent determinants for normalization. CONCLUSION Because TSH levels spontaneously normalized in a large proportion of older adults with subclinical hypothyroidism (also after confirmation by repeat measurement), a third measurement may be recommended before considering treatment. TRIAL REGISTRATION ClinicalTrials.gov, NCT01660126 and Netherlands Trial Register, NTR3851.
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Synbiotic as an ameliorating factor in the health-related quality of life in women with polycystic ovary syndrome. A randomized, triple-blind, placebo-controlled trial.
Hariri, Z, Yari, Z, Hoseini, S, Abhari, K, Sohrab, G
BMC women's health. 2024;24(1):19
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Polycystic ovary syndrome (PCOS), as a chronic endocrine disorder, can affect many aspects of young women’s lives. Apart from physical complications, women with polycystic ovary syndrome are more likely to suffer from mental and behavioural disorders. The aim of this study was to examine whether synbiotic supplementation could improve the health quality of life of women with PCOS. This study was a triple-blind, randomised clinical trial which recruited women with polycystic ovary syndrome. Participants were randomly divided into synbiotic or placebo groups for 12 weeks. Results showed that synbiotic supplementation improved the scores of emotional, body hair, weight and infertility domains of PCOSQ-26 compared to placebo group. Authors concluded that 12-week supplementation with synbiotics could noticeably improve the emotional, body hair, weight, infertility and general physical health status of women with polycystic ovary syndrome.
Abstract
BACKGROUND There are complicated mechanisms that link the disruption of the gut microbiome to the symptoms and complications of polycystic ovary syndrome (PCOS). In this study, an attempt was made to assess the effects of synbiotics on the health-related quality of life (HRQoL) in women with PCOS . METHODS Fifty-six women with PCOS were enrolled in a triple-blind controlled trial for 12 weeks. They were randomly assigned to receive a daily 2-gram synbiotic sachets (containing Bacillus coagulans (GBI-30), Lactobacillus rhamnosus, Lactobacillus helveticus, and fructooligosaccharide) (n = 28) or placebo (n = 28). To evaluate the impact on the HRQoL, participants were required to fill 26-Item Polycystic Ovary Syndrome Health-Related Quality of Life Questionnaire (PCOSQ-26), 12-Item Short-Form Health Survey (SF-12) and Perceived Stress Scale (PSS-10) pre and post the intervention. RESULTS Finally, statistical analyses were performed on 52 participants who finished the trial. Synbiotic supplementation improved the scores of emotional (P = 0.044), body hair (P = 0.016), weight (P = 0.033) and infertility domains (P = 0.027) of PCOSQ-26 compared to placebo group. The physical score within SF-12 also had a significant enhancement (P = 0.035). No significant improvement was seen in the PSS-10 score at the end of the trial. CONCLUSION This study illustrated the advantageous effects of synbiotics on the health-related quality of life in women with PCOS. Further studies are required to confirm our findings. TRIAL REGISTRATION http://www.irct.ir : IRCT20211108053007N1; date of registration: 14/02/2023.
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A systematic review and meta-analysis of the correlation between polycystic ovary syndrome and irritable bowel syndrome.
Wei, Z, Chen, Z, Xiao, W, Wu, G
Gynecological endocrinology : the official journal of the International Society of Gynecological Endocrinology. 2023;39(1):2239933
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The pathophysiology of polycystic ovarian syndrome (PCOS) and irritable bowel syndrome (IBS) remains elusive, the correlation between IBS and PCOS has been validated. This study's aim was to quantify the relationship between IBS and PCOS by estimating the odds ratio of IBS in PCOS patients. This study was a systematic review and meta-analysis of six studies in qualitative synthesis and five studies in quantitative synthesis. Results showed approximately 2.2 times elevated IBS risk in PCOS patient. Among six studies involved in this systematic review, a case-control study reported a negative relationship between IBS and PCOS, while most studies reported a positive association, which confirmed the pooled estimates results. Authors concluded that their study found a significant association between increased odds of IBS and PCOS.
Abstract
BACKGROUND Research on the prevalence of irritable bowel syndrome (IBS) among polycystic ovary syndrome (PCOS) patients has gained significant momentum over the years. However, it remains unclear whether PCOS is related to a higher prevalence of IBS. The objective of this systematic review and meta-analysis was to fully study IBS correlation with PCOS. METHODS From inception until October 16th, 2022, all observational studies documenting IBS prevalence in PCOS patients were collected from the China national knowledge infrastructure(CNKI), China Science and Technology Journal Database(VIP), Wanfang database, PubMed, Embase, Web of Science, and Cochrane databases. The quality of case-control studies was assessed with Newcastle-Ottawa Scale. Review Manager 5.3 was used to determine the pooled odds ratio (OR) and 95% confidence interval (CI). RESULTS 5 case-control studies involving 1268 individuals and one cross-sectional study involving 291 participants were included in our qualitative analysis. The quantitative analysis was conducted based on five case-control studies. Four case-control studies involving 1063 participants showed a higher prevalence of IBS in PCOS This meta-analysis revealed an almost twice higher risk of IBS in comparison with controls (OR = 2.23, 95%CI:1.58-3.14, p < 0.001; I2=41%, p = 0.150). Four sensitivity analyses validated the consistency of the aggregated findings. CONCLUSION This meta-analysis and systematic review demonstrated a significant association between PCOS and increased odds of IBS. However, more high-quality and well-controlled research is essential to increase the robustness of our conclusions.
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The effects of probiotics supplementation on glycaemic control among adults with type 2 diabetes mellitus: a systematic review and meta-analysis of randomised clinical trials.
Li, G, Feng, H, Mao, XL, Deng, YJ, Wang, XB, Zhang, Q, Guo, Y, Xiao, SM
Journal of translational medicine. 2023;21(1):442
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Type 2 diabetes mellitus (T2DM), an endocrine and metabolic disease, is influenced by host physiology and environmental factors. Recent studies have shown that the gut microbiota plays a key role in the maintenance of host homeostasis and pathogenesis of T2DM. The aim of this study was to evaluate the effects of a probiotic intervention on glycaemic control in T2DM patients and to evaluate the variations in these effects due to participant characteristics and intervention characteristics. This study was a systematic review and meta-analysis of thirty randomised-controlled studies including a total of 1,827 individuals. Results showed that probiotic supplementation had favourable effects on glycaemic control in T2DM patients. Bifdobacterium and food-type probiotics had greater glucose-lowering effects than other probiotic genera and types of vehicles used to deliver the probiotics. Authors concluded that the administration of probiotics may be a promising adjuvant therapy for glycaemic control in T2DM patients.
Abstract
OBJECTIVE This systematic review and meta-analysis study aimed to evaluate the effectiveness of probiotics supplementation on glycaemic control in patients with type 2 diabetes mellitus (T2DM) based on the data from the randomised clinical trials (RCTs). METHODS PubMed, Web of Sciences, Embase, and Cochrane Library were searched from the inception to October 2022, and RCTs about probiotics and T2DM were collected. The standardised mean difference (SMD) with 95% confidence interval (CI) was used to estimate the effects of probiotics supplementation on glycaemic control related parameters, e.g. fasting blood glucose (FBG), insulin, haemoglobin A1c (HbA1c), and homeostasis model of assessment of insulin resistance (HOMA-IR). RESULTS Thirty RCTs including 1,827 T2MD patients were identified. Compared with the placebo group, the probiotics supplementation group had a significant decrease in the parameters of glycaemic control, including FBG (SMD = - 0.331, 95% CI - 0.424 to - 0.238, Peffect < 0.001), insulin (SMD = - 0.185, 95% CI - 0.313 to - 0.056, Peffect = 0.005), HbA1c (SMD = - 0.421, 95% CI - 0.584 to - 0.258, Peffect < 0.001), and HOMA-IR (SMD = - 0.224, 95% CI - 0.342 to - 0.105, Peffect < 0.001). Further subgroup analyses showed that the effect was larger in the subgroups of Caucasians, high baseline body mass index (BMI ≥ 30.0 kg/m2), Bifidobacterium and food-type probiotics (Psubgroup < 0.050). CONCLUSION This study supported that probiotics supplementation had favourable effects on glycaemic control in T2DM patients. It may be a promising adjuvant therapy for patients with T2DM.
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Effect of supplementation with probiotics or synbiotics on cardiovascular risk factors in patients with metabolic syndrome: a systematic review and meta-analysis of randomized clinical trials.
Chen, T, Wang, J, Liu, Z, Gao, F
Frontiers in endocrinology. 2023;14:1282699
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Metabolic syndrome (metS) is characterised by insulin resistance, dyslipidaemia, central obesity and/or high blood pressure and is a significant risk factor for cardiovascular disease and type 2 diabetes mellitus. MetS is associated with an imbalanced microbiome and some but not all studies have shown benefits of supplementation with probiotics. The aim of this systematic review and meta-analysis of randomised controlled trials was to evaluate the effects of pro- or synbiotics on cardiovascular risk factors (body mass index, LDL cholesterol, fasting blood glucose and systolic blood pressure) in patients with metS. 11 studies were included in the review of which 7 were judged to have a low risk of bias, whilst risk of bias was unclear in 4 articles. The meta-analysis found that pro- or synbiotics have a positive effect on body mass index, LDL cholesterol and fasting blood glucose but not on systolic blood pressure. Subgroup analysis of pro- and synbiotics separately also found no effects on systolic blood pressure.
Abstract
PURPOSE The effectiveness of probiotics or synbiotics in adults with metabolic syndromes (MetS) remains controversial, this meta-analysis will further analyze the effects of probiotics or synbiotics on cardiovascular factors in adults with MetS. METHODS We searched Web of Science, PubMed, Embase, Cochrane Library and other databases for randomized controlled trials (RCTs) on the effects of probiotics or synbiotics on MetS in adults up to July 2023, and used RevMan 5.4.0 software for statistical analysis. RESULTS This analysis included eleven RCTs (n = 608 participants), and the results showed that compared with the control group, supplementation with probiotics or synbiotics reduced body mass index (weighted mean difference, WMD = -0.83, 95% CI = [-1.21, -0.44], P <0.0001, n = 9), low-density lipoprotein (LDL-c) (standard mean difference, SMD = -0.24, 95% CI = [-0.41, -0.08], P = 0.004, n = 10), fasting blood glucose (FBG)(SMD = -0.17, 95% CI = [-0.33, -0.01], P = 0.03, n = 11), but had no beneficial effect on systolic blood pressure (SBP) (WMD = 1.24, 95% CI = [-2.06, 4.54], P = 0.46, n = 8) in MetS patients. CONCLUSION Supplementation with probiotics or synbiotics can reduce BMI, LDL-c, FBG in patients with MetS, but our findings did not demonstrate a favorable effect on reducing SBP. Future studies with larger samples and longer intervention periods are needed.
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Are probiotics, prebiotics, and synbiotics beneficial in primary thyroid diseases? A systematic review with meta-analysis.
Zawadzka, K, Kałuzińska, K, Świerz, MJ, Sawiec, Z, Antonowicz, E, Leończyk-Spórna, M, Abadi, AK, Trofimiuk-Müldner, M, Bała, MM
Annals of agricultural and environmental medicine : AAEM. 2023;30(2):217-223
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Irregularities in intestinal microbial composition are thought to be correlated with thyroid dysfunction. Supplementation of prebiotics, probiotics and synbiotics are gaining momentum in recent times in improving health in general. This systematic review of randomised controlled trials was conducted to summarise the up-to-date evidence on the therapeutic potential of prebiotics, probiotics and synbiotics in the treatment of thyroid disease. The meta-analysis did not show beneficial effects on thyroid hormone balance, BMI or levothyroxine dosage reduction. Supplementation with Lactobacillus and Bifidobacterium resulted in improvement in constipation and a statistically non-significant reduction in thyroid-stimulating hormone in adult participants with hypothyroidism. Further robust long-term studies are required to evaluate the efficacy of prebiotics, probiotics and synbiotics in thyroid disease treatment as the availability of the number of studies included in this systematic review was limited. However, healthcare professionals can use the review to understand the current evidence in this area and the correlation between gut microbial alterations and thyroid disease.
Abstract
INTRODUCTION AND OBJECTIVE A number of studies indicate the presence of a thyroid-gut axis and the important influence of the gut microbiota on thyroid function. As prebiotics, probiotics and synbiotics show therapeutic potential in the treatment of intestinal dysbiosis, the aim of this review is to evaluate the efficacy of their supplementation in primary thyroid diseases. REVIEW METHODS Electronic databases (Ovid MEDLINE, Embase, CENTRAL), registers of clinical trials, and grey literature up to 6 October 2022 were searched for randomised controlled trials (RCTs) meeting pre-specified inclusion criteria. The protocol was registered in PROSPERO (CRD42021235054). BRIEF DESCRIPTION OF THE STATE OF KNOWLEDGE After screening 1,721 references, two RCTs were identified, which included 136 hypothyroid participants in total. Meta-analysis of the results after eight weeks of supplementation with predominantly Lactobacillus and Bifidobacterium strains indicated a clinically and statistically nonsignificant decrease in TSH (MD -0.19 mIU/L; 95% CI -0.43 to 0.06; I2= 0%), and no effect on fT3 levels (MD 0.01 pg/mL; 95% CI-0.16 to 0.18; I2= 0%). Data from single studies indicated no significant change in the levels of fT4, thyroid auto-antibodies, BMI, levothyroxine doses, and severity of symptoms measured with validated scales. Only constipation scores showed significant improvement (MD -8.71 points in the Faecal Incontinence Questionnaire; 95% CI -15.85 to -1.57; I2= 0%). SUMMARY Low-certainty evidence from two randomised trials, suggests that routine administration of probiotics, prebiotics or synbiotics may result in little to no benefit in patients with primary hypothyroidism.