Interactive relationship between Trp metabolites and gut microbiota: The impact on human pathology of disease.

Tryptophan (Trp), an α-amino acid, is the precursor of serotonin (5-hydroxytryptamine, 5-HT), which is involved in a variety of features of metabolic function and human nutrition. Evidence highlights the role of Trp metabolites (exclusively 5-HT) in the gastrointestinal (GI) tract; however, the mechanisms of action involved in the release of 5-HT in the GI tract are still unknown. Considering the fact that variations of 5-HT may facilitate the growth of certain GI disorders, gaining a better understanding of the function and release of 5-HT in the GI tract would be beneficial. Additionally, investigating Trp metabolism may clarify the relationship between Trp and gut microbiota. It is believed that other metabolites of Trp (mostly that of the kynurenine pathway) may play a significant role in controlling gut microbiota function. In this review, we have attempted to summarize the current research investigating the relationship of gut microbiota, Trp and 5-HT metabolism (with particular attention paid to their metabolite type, as well as a discussion of the research methods used in each study). Taking together, regarding the role that Trp/5-HT plays in a range of physical and mental diseases, the gut bacterial types, as well as the related disorders, have been exclusively considered.

The interactive effect of vitamin D3 supplementation and vitamin D receptor polymorphisms on weight and body composition in overweight women with hypovitaminosis D: a randomized, double-blind, placebo-controlled clinical trial.

Different responses to vitamin D supplementation may be due to genes involved in vitamin D metabolism, including the vitamin D receptor (VDR) gene. The present study aimed to determine the interactive effect of vitamin D supplementation and VDR polymorphisms, including FokI (rs2228570) and BsmI (1544410) on weight and body composition in overweight women with hypovitaminosis D. This study comprised two phases: a double-blind, randomized and a before-after clinical trial. In the first phase, 50 healthy overweight women aged 20-45 years with hypovitaminosis D were randomly categorized into intervention and control groups and were given 50 000 IU/w vitamin D3 or placebo for 12 weeks. In the second phase, 75 women received 50 000 IU/w of vitamin D3 for 12 weeks. All variables were measured at baseline and after 12 weeks. Circulating 25(OH)D was measured using an ELISA kit. Anthropometric indices were calculated according to standard protocol (WHO-TRH-854). Body composition was determined using the body impedance analysis method. The VDR polymorphisms were detected using the PCR sequence. Supplementation resulted in a significant increase in the level of 25(OH)D in the intervention group but did not affect the anthropometric profile of the subjects. When considering FokI genotypes, carriers of the FF genotype had higher fat mass reduction than carriers of Ff + ff genotypes.

Is There Any Link between Cognitive Impairment and Gut Microbiota? A Systematic Review.

BACKGROUND: Symptoms of cognitive impairments vary from mild without clinical manifestation to severe with advanced signs of dementia or Alzheimer's disease (AD). Growing evidence in recent years has indicated the association between the brain and gut microbiota, which has been described as the "gut-brain axis." This systematic review seeks to summarize the primary results from recent human and animal studies regarding the alteration of gut microbiota composition in cognitive disorders. METHODS: A systematic literature search was conducted on PubMed, Scopus, and Web of Science databases up to August 2020. The full texts of the papers were analyzed to retrieve the relevant information. RESULTS: Totally, 24 observational studies (14 animal and 13 human studies) were included. Most of the animal studies were performed on mouse models of AD. Human studies were conducted on patients with Parkinson's disease (3 studies), AD (4 studies), poststroke cognitive impairment patients (1 study), and patients with mild to severe cognitive impairment without mention to the cause of disease (5 studies). More recent evidence suggests that throughout aging Firmicutes and Bifidobacteria decrease but Proteobacteria increases. CONCLUSIONS: The gut microbiota may alter brain function or trigger various psychiatric conditions through the gut-brain axis. Prospective studies are needed in order to explore the role of the gut microbiota in the etiology of dementia and to achieve clinical recommendations.

Determinants of life satisfaction and self-rated health in Iranian children and adolescents: a structure equation model.

BACKGROUND: Life satisfaction (LS) and self-rated health (SRH) are related with health outcomes. It is expected that these items are also related to healthy behaviors. Therefore, this study was conducted in order to find out the main determinants of LS and SRH in nationwide representative sample of Iranian children and adolescents. METHODS: This study was performed on 13,834 students aged 7-18 years who were selected by multistage, stratified cluster sampling method from 30 provinces of Iran. Life satisfaction and SRH were assessed through a questionnaire based on World Health Organization-Global School-based Student Health Survey protocols. Path analysis was applied to evaluate the relationships among the study variables using the structural modeling. RESULTS: Life satisfaction was directly affected by age (- 0.037 in boys & -0.028 in girls); sedentary time (0.055 in boys & 0.048 in girls); school satisfaction (0.249 in boys & 0.250 in girls); and well-being (0.186 in boys & 0.176 in girls). Self-rated health was directly affected by LS (0.28 in boys & girls) and school satisfaction (0.21 in boys & 0.22 in girls); and indirectly affected by age (- 0.046 in boys & -0.017 in girls); sedentary time (- 1.99 in boys & -0.145 in girls); family size (- 0.005 in boys & -0.014 in girls); and socio-economic status (0.015 in boys & 0.058 in girls). CONCLUSIONS: This study indicated that school satisfaction had the greatest positive direct effect on both LS and SRH.

A comparison between body mass index and waist circumference for identifying continuous metabolic syndrome risk score components in Iranian school-aged children using a structural equation modeling approach: the CASPIAN-V study.

PURPOSE: The purpose of this study was to investigate the association of anthropometric indices with continuous metabolic syndrome (cMetS) risk score components in a large population-based sample of children and adolescents. METHODS: This multi-centric study was performed on 3843 students aged 7-18 years who were selected by multistage, stratified cluster sampling method from 30 provinces of Iran. Demographic, anthropometric and biochemical factors were obtained and standardized residuals (z-scores) were calculated for MetS components. A structural equation modeling approach was applied to evaluate the relationships among the study variables and to implement the subsequent structural modeling. RESULTS: The mean age of the participants (52.3% boys) was 12.4 ± 3.05 years. Standardized scores of body mass index (ZBMI) and waist circumference (ZWC) had a direct effect on standardized scores of mean arterial pressure (ZMAP) (0.23 and 0.24 in boys and 0.22 and 0.23 in girls, respectively) and triglyceride (ZTG) (0.07 and 0.04 in boys and 0.02 and 0.06 in girls, respectively), but the effect of ZWC was stronger than ZBMI on these variables. Age, socioeconomic status and sedentary behaviors showed a positive direct effect on ZWC (0.01, 0.05 and 0.07 in boys and 0.05, 0.08 and 0.002 in girls, respectively). These variables induced indirect effects on cMets risk score components through ZWC. CONCLUSION: The magnitude of association between WC and continuous metabolic syndrome risk score components was higher compared to BMI in school-aged children, emphasizing on paying more attention to central obesity in childhood. LEVEL OF EVIDENCE: Level V, cross-sectional descriptive study.

Determinants of childhood blood pressure using structure equation model: the CASPIAN-V study.

BACKGROUND: Childhood hypertension is a predictor of later diseases, increases the risk for cardiovascular morbidity and mortality in adulthood and results in major economic burdens. The purpose of this study was to investigate the direct and indirect effect of anthropometric, socioeconomic and lifestyle factors on blood pressure (BP) in a large population-based sample of children and adolescents using a path analysis. METHODS: This multi-centric nationwide study was performed on students aged 7-18 years. Anthropometric indices and blood pressure were measured by standard methods and demographic data, socioeconomic status, dietary habits and health related behaviors were obtained using validated questionnaires. Path analysis was applied to evaluate the relationships among the study variables and to implement the subsequent structural modeling. RESULTS: Totally, 7235 students (50.6% boys; the mean age 12.3 ± 3.1 years) were assessed. Systolic and diastolic BP positively correlated with age (r = 0.35 and 0.26; respectively), BMI (r = 0.06 and 0.04; respectively) and WC (r = 0.05 and 0.03; respectively). According to path analysis, age had significant direct effect on BMI, WC, and BP (ß = 0.035, 0.043 and 0.345; respectively), which was greater for BP. BMI and WC had the greatest direct effect on BP (ß = 0.05 and 0.03; respectively). Education level, subjective health complaints, health-related behaviors and dietary habits had positive direct effects on BP (ß = 0.036, 0.030, 0.018 and 0.017; respectively). Socioeconomic status and positive changes in diet had negative indirect effect on BP (ß = - 0.001 for both). CONCLUSION: Our findings strengthen the importance of weight and body composition in BP control. It is suggested to improve diet and health related behaviors especially in families with low socioeconomic position.

Utility of waist circumference-to-height ratio as a screening tool for generalized and central obesity among Iranian children and adolescents: The CASPIAN-V study.

BACKGROUND: Waist-to-height ratio (WHtR) is regarded as a simple anthropometric index for evaluating central adiposity because of its independence of age, gender, and ethnicity. OBJECTIVE: The purpose of this study was to determine the optimal WHtR cutoff value in screening obesity and to compare it with other obesity indicators including body mass index (BMI) and waist circumference (WC) in Iranian children and adolescents. METHODS: This large survey was conducted on 14 274 Iranian children and adolescents as a national school-based surveillance study (CASPIAN) in 2015. The receiver operating characteristic curve analysis was performed to estimate the optimal cut-off points of WHtR for the prediction of general and central obesity. The area under curve (AUC) was used to compare the ability of WHtR cut-off points, BMI and WC percentiles to discriminate students with and without obesity according to age and sex. RESULTS: The optimal WHtR cutoff value for predicting general obesity was 0.49 and 0.48 for boys and girls, respectively and for central obesity according to WC ≥ 90th percentile was 0.50 for both genders. AUC values of WHtR for predicting general and central obesity were 87% and 96%, which indicates its strong predictive ability. For central obesity, the AUCs of WHtR were superior to those of WC percentiles. The kappa agreement coefficient was 0.55 between WC ≥ 90th percentile and WHtR ≥ 0.5. CONCLUSIONS: The WHtR ≥ 0.5 as a simple and useful screening tool is better than WC, for predicting general and central obesity in different age and sex groups of Iranian children and adolescents.

Adaptation of human gut microbiota to bariatric surgeries in morbidly obese patients: A systematic review.

BACKGROUND: Bariatric surgeries have turned to be a popular therapeutic option for morbid obesity nowadays. Gut microbiota is supposed to be responsible as a part of the bariatric surgeries success. In this systematic review, we detailed the human studies which investigated the effect of different bariatric surgeries on the composition of gut microbiota. METHODS: We did a comprehensive search in PubMed, Web of Science, and Scopus for all clinical trials and longitudinal observational studies documented up to December 2015. RESULTS: Our initial search yielded 1423 articles. After screening abstracts and full texts, 7 articles were included. In 6 studies, the type of surgical intervention was Roux-en-Y gastric bypass (RYGB) where one study assessed vertical banded gastroplasty (VBG), too. Only in one study the effect of laparoscopic sleeve gastrectomy (LSG) had been investigated. RYGB caused an increase in Proteobacteria and a decrease in Firmicutes. LSG led to less severe intestinal microbiota alteration compared to RYGB. Fecalibacterium prausnitzii species with anti-inflammatory properties increased after LSG. However, inconsistent alterations have been shown in abundance of Fecalibacterium species after RYGB. CONCLUSION: Weight loss after bariatric surgeries are associated with microbiota modifications caused by surgical procedures.

Are non-high-density lipoprotein fractions associated with pediatric metabolic syndrome? The CASPIAN-V study.

BACKGROUND: Non-high-density lipoprotein cholesterol (non-HDL-C) is considered as a valuable predictor for dyslipidemia and subclinical atherosclerosis which can be an appropriate index for identifying individuals with metabolic syndrome (MetS). OBJECTIVE: To evaluate the association between non-HDL-C MetS and determine the optimal cut-points of non-HDL-C fractions for identifying MetS in Iranian children and adolescents. METHODS: This nationwide study was conducted in the framework of the fifth survey of a national school-based surveillance program on children and adolescents aged 7-18 years. MetS was defined by the Adult Treatment Panel III (ATP III) criteria modified for the pediatric age group. The analysis of receiver operating characteristic (ROC) curve was applied to determine the optimal cut-points of non-HDL-C, difference between non-HDL-C and LDL-C (Diff-C) and triglycerides (TG) to HDL-C ratio (TG/HDL-C) for the prediction of MetS. RESULTS: Overall, the study participants consisted of 3843 students (52.3% boys) with mean (±SD) age of 12.28 (3.1) years. The odds of high LDL-C, low HDL-C and MetS were increased in subjects with higher non-HDL-C, Diff-C and TG/HDL-C (P < 0.05). Non-HDL-C, Diff-C and TG/HDL-C cut-off points for predicting MetS were 120.5 mg/dl (sensitivity: 44%, specificity: 73%), 19.9 mg/dl (sensitivity: 85%, specificity: 75%) and 2.53 (sensitivity: 82%, specificity: 79%), respectively. CONCLUSIONS: This study revealed a strong association between surrogates for serum lipid profile including non-HDL-C, TG/HDL-C and Diff-C and pediatric MetS. Our findings suggest that age- and gender-specific reference values of these markers were appropriate for both risk classification and long-term control of cardiovascular events in clinical assessments.

Association of anthropometric indices with continuous metabolic syndrome in children and adolescents: the CASPIAN-V study.

PURPOSE: This study aims to examine the association of anthropometric indices with continuous metabolic syndrome (cMetS) among Iranian children and adolescents. METHODS: This multicentric study was conducted on 14138 students aged 7-18 years, who participated in a national surveillance program. Fasting blood sample was obtained from a subsample of 3843 randomly selected students. Physical examination including the measurement of anthropometric indices and blood pressure was conducted; fasting blood glucose and lipid profile were measured; and cMetS score was computed. Standardized residuals (z-scores) were calculated for MetS components. A higher cMetS score indicates a less favorable metabolic profile. Linear regression models were applied to determine the association between cMetS and anthropometric indices. RESULTS: The study participants consisted of 3843 children and adolescents (52.3% boys) with mean (SD) age of 12.45 ± 3.04 years. All anthropometric indices had positive correlation with standardized scores of mean arterial pressure, waist circumference and cMetS (P < 0.05). Standardized scores of triglycerides were positively correlated with weight and body mass index (P < 0.05). In multivariate model, general and abdominal obesity, as well as high circumferences of neck, wrist, and hip circumferences increased the standardized cMetS risk score to 1.8, 1.9, 1.6, 1.5 and 1.5, respectively (P < 0.05 for all variables). CONCLUSION: The results demonstrated that higher anthropometric indices are associated with higher cMetS risk score in children and adolescents. This information could be valuable for screening and prevention of MetS at population level. LEVEL OF EVIDENCE: V, cross-sectional descriptive study (National surveillance study).

Validity of triglyceride-glucose index as an indicator for metabolic syndrome in children and adolescents: the CASPIAN-V study.

PURPOSE: The purpose of this study was to determine the cut-off values of triglycerides and glucose (TyG) index as one of the indirect indices for metabolic syndrome (MetS) in a pediatric population. METHODS: This national study was conducted in 2015 on 14400 students, aged 7-18 years. They were selected by random cluster sampling from 30 provinces of our country during the fifth survey of a national school-based surveillance program. MetS was defined based on the Adult Treatment Panel III (ATP III) criteria modified for the pediatric age group. The cut-off values of TyG index for MetS were obtained using the receiver operation characteristic (ROC) curve analysis by gender and age groups. RESULTS: Totally, 3843 students (52.3% boys) with mean (SD) age of 12.45 (3.04) years were assessed. The area under the ROC curve of TyG index for MetS was 0.83 in total participants. According to the ATP III criteria the cut-off values of the TyG index were 8.33 (8.21-8.45) in total students, 8.47 (8.36-8.58) in boys, and 8.33 (8.18-8.48) in girls. In the 7-12 and 13-18 years' age groups, these values were 8.47 (8.32-8.63) and 8.34 (8.22-8.45) in total, 8.39 (8.26-8.52) and 8.47 (8.33-8.61) in boys, 8.33 (8.11-8.55) and 8.35 (8.22-8.47) in girls, respectively. CONCLUSION: The findings of this study can be clinically helpful for screening MetS in children and adolescents but the effectiveness of these criteria needs to be evaluated by further longitudinal surveys. LEVEL OF EVIDENCE: Level V, cross-sectional descriptive study (National surveillance study).

Effects of pomegranate juice consumption on oxidative stress in patients with type 2 diabetes: a single-blind, randomized clinical trial.

Increased free radicals production due to hyperglycemia produces oxidative stress in patients with diabetes. Pomegranate juice (PJ) has antioxidant properties. This study was conducted to determine the effects of PJ consumption in oxidative stress in type 2 diabetic patients. This study was a randomized clinical trial performed on 60, 40-65 years old diabetic patients. The patients were randomly allocated either to PJ consumption group or control. Patients in PJ group consumed 200 ml of PJ daily for six weeks. Sex distribution and the mean age were not different between two groups. After six weeks intervention, oxidized LDL and anti-oxidized LDL antibodies decreased and total serum antioxidant capacity and arylesterase activity of paraoxonase increased significantly in the PJ-treated group compared to the control group. Our data have shown that six weeks supplementation of PJ could have favorable effects on oxidative stress in patients with type 2 diabetes (T2D).

Dietary Advanced Glycation End Products and Risk of Chronic Kidney Disease.

OBJECTIVES: To evaluate the longitudinal association between dietary advanced glycation end products (AGEs) and risk of chronic kidney disease (CKD) in a population-based study. DESIGN AND SETTING: In a longitudinal design study, participants were evaluated after approximately 3 years. Daily consumption of carboxymethyl lysine, a major type of dietary AGEs, was determined using a validated semiquantitative food frequency questionnaire. Estimated glomerular filtration rate in this study was calculated by the Modification of Diet in Renal Disease formula. CKD was defined as estimated glomerular filtration rate <60 mL/min/1.73 m(2) based on the national kidney foundation guidelines. SUBJECTS: A total of 1,692 participants, free of baseline CKD with complete follow-up data, out of 3,462 subjects, age ≥27 years of the third phase of Tehran Lipid and Glucose Study. MAIN OUTCOME MEASURES: The association between dietary AGEs and CKD was assessed using the multivariate logistic regression models. RESULTS: The mean age of participants was 43.4 ± 11.4 years. The mean dietary intake of energy-adjusted AGEs was 8,336 ± 1,532 kU/day. By increasing trend of AGE consumption, the percentage of fat intake increased (P < .001), whereas the percentage of carbohydrates and total fiber intake decreased (P < .001). Longitudinal analysis indicated that compared to the first quartile category of AGE intakes from fat, in participants of the fourth quartile category, the risk of CKD increased (odds ratio: 2.02; 95% confidence interval: 1.16-3.54). The odds of CKD had increasing trends across increasing categories of AGE intakes from fat (P for trend <.05). CONCLUSION: Higher consumption of AGEs through dietary fat was associated with higher risk of CKD incidence.

Dietary consumption of advanced glycation end products and risk of metabolic syndrome.

Metabolic syndrome (MetS) is a complex disorder which has become one of the major public health challenges worldwide. This study was conducted to evaluate the association between dietary advanced glycation end products (AGEs) and risk of MetS and its components. This cross-sectional study was conducted in a representative sample of 5848 adults, aged 19-70 years. Daily consumption of carboxymethyl lysine, a major type of AGEs, was determined using a validated semi-quantitative food frequency questionnaire. Across increasing trend of AGEs consumption, the percentage of fat intake increased and that of carbohydrate significantly decreased (p < 0.001). Subjects in the highest (>10,506 kU/d) compared to the lowest (<6673 kU/d) quartile category of AGEs had higher risk of abdominal obesity (OR: 1.19, 95% CI: 1.01-1.39) and hypertriglyceridemia (OR: 1.26, 95% CI: 1.07-1.49). Therefore, recommendation on restriction of AGEs intake could be a practical approach to prevent metabolic abnormalities.

Adherence to the Mediterranean diet can beneficially affect the gut microbiota composition: a systematic review.

AIM: Dietary patterns could have a notable role in shaping gut microbiota composition. Evidence confirms the positive impact of the Mediterranean diet (MD), as one of the most studied healthy dietary patterns, on the gut microbiota profile. We conducted this systematic review to investigate the results of observational studies and clinical trials regarding the possible changes in the gut microbiota composition, metabolites, and clinical outcomes following adherence to MD in healthy cases or patients suffering from metabolic disorders. METHODS: A systematic literature search was conducted on PubMed, Web of Science, and Scopus databases until October 2023. Two researchers separately screened the titles, abstracts, and then full-text of the articles and selected the relevant studies. Quality assessment of observational and interventional studies was performed by Newcastle-Ottawa and Cochrane checklists, respectively. RESULTS: A total of 1637 articles were obtained during the initial search. Ultimately, 37 articles, including 17 observational and 20 interventional studies, were included in this systematic review. Ten observational and 14 interventional studies reported a correlation between MD adherence and microbiota diversity. Faecalibacterium and Prevotella were the most frequent bacterial genera with increased abundance in both observational and interventional studies; an Increment of Bacteroides genus was also reported in observational studies. Better glycemic control, lowering fat mass, better bowel movement, decreased bloating, inflammation, and hospitalization risk were the reported clinical outcomes. CONCLUSION: Adherence to the MD is associated with significant beneficial changes in the gut microbiota diversity, composition, and functions and major clinical improvements in most populations.

The effects of probiotics, prebiotics, and synbiotics on polycystic ovarian syndrome: an overview of systematic reviews.

Introduction: Accumulating evidence has highlighted the critical role of the gut microbiota and its potential action as a regulator of metabolic disorders including insulin resistance, obesity, and systemic inflammation in polycystic ovarian syndrome (PCOS). Microbiota-modulating interventions, such as probiotics, prebiotics, and synbiotics, could be effective in PCOS management. Methods: We conducted an overview of systematic reviews (SRs) and meta-analyses to summarize reviews regarding the effectiveness of probiotics/prebiotics/synbiotics on the management of PCOS through a systematic literature search in PubMed, Web of Science, and Scopus databases until September 2021. Results: Eight SRs and meta-analyses were included in this study. Our overview confirmed that probiotic supplementation had a potentially beneficial effect on some PCOS-related parameters including body mass index (BMI), fasting plasma glucose (FPG), and lipid profiles. Evidence shows that synbiotics in comparison with probiotics were less effective on these parameters. The methodological quality of SRs was assessed using the AMSTAR-2 assessment tool and was determined as high for four SRs, low for two SRs, and critically low for one SR. Due to limited evidence and high heterogeneity of the studies, it remains difficult to identify optimal probiotics strains, prebiotics types, length of duration, and doses. Discussion: Future clinical trials with higher quality are recommended to clarify the efficacy of probiotics/prebiotics/synbiotics on the management of PCOS and provide more accurate evidence.

Gut microbiota modulation as a possible mediating mechanism for fasting-induced alleviation of metabolic complications: a systematic review.

BACKGROUND: Intermittent fasting has been reported to have positive effects on obesity, diabetes, cardiovascular diseases, hypertension, and several neurodegenerative diseases through different mechanisms such as alteration in the gut microbiota. This systematic review was conducted with the aim of providing an overview of the existing animal and human literature regarding the gut microbiota alterations in various fasting regimens. METHOD: A systematic literature search was conducted on PubMed, Scopus and Web of Science databases up to May 2021 to find all relevant studies examining the gut microbiota alteration during the fasting. Original researches on animal models or human patients were included in this study. RESULTS: The search fulfilled 3072 documents from which 31 studies (20 animal and 11 human studies) were included. Upon fasting, abundance of several beneficial bacteria including Lactobacillus and Bifidobacterium shifted significantly. Moreover, some taxa, including Odoribacter which negatively associated with blood pressure bloomed during fasting. Ramadan fasting, as a kind of intermittent fasting, improves health parameters through positive changes in gut microbiota including upregulation of A. muciniphila, B. fragilis, Bacteroides and butyric acid-producing Lachnospiraceae. CONCLUSION: The findings suggest that different fasting regimens including alternate-day fasting, calorie- and time-restricted fasting programs and Ramadan fasting could promote health maybe through the modulation of gut microbiome. However, further studies are needed to explore properly the connection between gut microbiota and meal frequency and timing.

Our Little Friends with Big Roles: Alterations of the Gut Microbiota in Thyroid Disorders.

BACKGROUND: The thyroid gland influences the metabolic processes in our body by producing thyroid hormones, and thyroid disorders can range from a harmless goiter to life-threatening cancer. A growing number of evidence support the link between gut microbiota composition and thyroid homeostasis. Gut dysbiosis can disrupt the normal gut barrier function, leading to immunologic and metabolic disorders. OBJECTIVE: The aim of this review was to discuss the main features of gut dysbiosis associated with different thyroid disorders. RESULTS: Gut microbiota contributes to thyroid hormone synthesis and hydrolysis of thyroid hormones conjugates. It has been shown that microbial metabolites may play a role in autoimmune thyroid diseases via modulating the immune system. Intestinal microbiota can contribute to the thyroid malignancies via controlling DNA damage and apoptosis and influencing inflammatory reactions by the microbiota- derived metabolites. However, the pathogenic role of altered gut microbiota in different thyroid disorders has not yet fully elucidated. CONCLUSION: Further research is needed to assess the role of alterations of the gut microbiota in disease onset and development in order to achieve novel strategies for the prevention and treatment of these diseases.

Gut microbiota-derived metabolites in obesity: a systematic review.

Recent evidence suggests that gut microbiota-derived metabolites affect many biological processes of the host, including appetite control and weight management. Dysbiosis of the gut microbiome in obesity influences the metabolism and excretion of gut microbiota byproducts and consequently affects the physiology of the host. Since identification of the gut microbiota-host co-metabolites is essential for clarifying the interactions between the intestinal flora and the host, we conducted this systematic review to summarize all human studies that characterized the gut microbiota-related metabolites in overweight and obese individuals. A comprehensive search of the PubMed, Web of Science, and Scopus databases yielded 2,137 articles documented up to July 2018. After screening abstracts and full texts, 12 articles that used different biosamples and methodologies of metabolic profiling and fecal microbiota analysis were included. Amino acids and byproducts of amino acids, lipids and lipid-like metabolites, bile acids derivatives, and other metabolites derived from degradation of carnitine, choline, polyphenols, and purines are among the gut microbiota-derived metabolites which showed alterations in obesity. These metabolites play an important role in metabolic complications of obesity, including insulin resistance, hyperglycemia, and dyslipidemia. The results of this study could be useful in development of therapeutic strategies with the aim of modulating gut microbiota and consequently the metabolic profile in obesity.

Discriminatory ability of visceral adiposity index as an indicator for modeling cardio-metabolic risk factors in pediatric population: the CASPIAN-V study.

Introduction: The purpose of this study was to obtain the cutoff points of visceral adiposity index (VAI), a new marker of indirect evaluation of visceral fat, to assess its association with metabolic syndrome (MetS) in a population of children and adolescents. Methods: This cross sectional study was conducted on children and adolescents aged 7-18 years attended in the fifth phase of a national school-based surveillance survey. The odds ratio (OR) of cardiometabolic risk factors across tertile categories of VAI was determined using the logistic regression models and the valid cut-off values of VAI for predicting MetS was obtained using the receiver operation characteristic (ROC) curve analysis. Results: A total of 3843 students (52.3% boys, 12.3 [12.2-12.4] years) were included in the analysis. The mean of VAI was significantly higher in participants who had MetS (2.60 [2.42-2.78] vs 1.22 [1.19-1.25]; P <0.001). Participants in the third tertile compared to the first tertile category of VAI had higher odds of abdominal obesity (OR: 1.77, 95% CI: 1.43-2.20), impaired fasting blood glucose (OR: 2.00, 95% CI: 1.28-3.13) and low high-density lipoprotein cholesterol (OR: 15.93, 95% CI: 12.27-20.66). The cut-off points of the VAI for predicting MetS were 1.58, 1.30 and 1.78 in total population, boys and girls, respectively. Conclusion: We determined the cut-off points of VAI as an easy tool for detecting MetS in children and adolescents and demonstrated that VAI is strongly associated with MetS. Prospective longitudinal studies are suggested to show the possible efficiency of the VAI as a predictor of MetS in pediatrics.