Effects of three medical nutrition therapies on nutritional metabolism and intestinal flora in overweight/obese with polycystic ovary syndrome (PCOS): Study protocol for a randomised controlled trial.

BACKGROUND AND OBJECTIVES: Observational studies have shown that energy restriction could be beneficial for controlling bodyweight in patients with polycystic ovary syndrome (PCOS). We aim to compare the effects of a high-protein diet (HPD), a high-protein and high-dietary fiber diet (HPHFD), and a calorie-restricted diet (CRD) on metabolic health and gut microbiota in overweight/obese PCOS patients. METHODS AND STUDY DESIGN: We will enroll a total of 90 overweight/obese PCOS patients into this eight-week open-label randomised controlled trial. Participants will be randomly assigned to three groups: CRD group (energy coefficient 20 kcal/kg.day, water ≥1500 mL, 0.8-1.2 g/kg protein, carbohydrate energize 55-60%, and fat energize 25-30%), HDP group (energy coefficient 20 kcal/kg.day, water ≥1500 mL, and 1.5-2.0 g/kg protein) and HPHFD group (based on the high protein diet with 15 g more dietary fiber supplement). The primary outcome is body weight, body fat percentage, and lean body mass. The secondary outcomes will include changes in blood lipids, inflammation, glucose tolerance, blood pressure, and gut microbiota compositions. Between-group differences in adiposity measurements at baseline will be compared using one-way analysis of variance (ANOVA) or Kruskal-Wallis test when appropriate. Within-group difference after 8-week intervention will be compared using paired t-test or Wilcoxon signed rank test. Between-group differences in adiposity measurements after 8-week diet intervention will be compared using linear mixed model and ANCOVA. The gut microbiota will be analyzed using 16S amplicon sequencing and the sequencing data will be analyzed using the standardized QIIME2 piperline.

Assessment of causal direction between thyroid function and cardiometabolic health: a Mendelian randomization study.

BACKGROUND: Growing evidence have demonstrated that thyroid hormones have been involved in the processes of cardiovascular metabolism. However, the causal relationship of thyroid function and cardiometabolic health remains partly unknown. METHODS: The Mendelian randomization (MR) was used to test genetic, potentially causal relationships between instrumental variables and cardiometabolic traits. Genetic variants of free thyroxine (FT4) and thyrotropin (TSH) levels within the reference range were used as instrumental variables. Data for genetic associations with cardiometabolic diseases were acquired from the genome-wide association studies of the FinnGen, CARDIoGRAM and CARDIoGRAMplusC4D, CHARGE, and MEGASTROKE. This study was conducted using summary statistic data from large, previously described cohorts. Association between thyroid function and essential hypertension (EHTN), secondary hypertension (SHTN), hyperlipidemia (HPL), type 2 diabetes mellitus (T2DM), ischemic heart disease (IHD), myocardial infarction (MI), heart failure (HF), pulmonary heart disease (PHD), stroke, and non-rheumatic valve disease (NRVD) were examined. RESULTS: Genetically predicted FT4 levels were associated with SHTN (odds ratio = 0.48; 95% CI = 0.04-0.82,P = 0.027), HPL (odds ratio = 0.67; 95% CI = 0.18-0.88,P = 0.023), T2DM (odds ratio = 0.80; 95% CI = 0.42-0.86,P = 0.005), IHD (odds ratio = 0.85; 95% CI = 0.49-0.98,P = 0.039), NRVD (odds ratio = 0.75; 95% CI = 0.27-0.97,P = 0.039). Additionally, genetically predicted TSH levels were associated with HF (odds ratio = 0.82; 95% CI = 0.68-0.99,P = 0.042), PHD (odds ratio = 0.75; 95% CI = 0.32-0.82,P = 0.006), stroke (odds ratio = 0.95; 95% CI = 0.81-0.97,P = 0.007). However, genetically predicted thyroid function traits were not associated with EHTN and MI. CONCLUSIONS: Our study suggests FT4 and TSH are associated with cardiometabolic diseases, underscoring the importance of the pituitary-thyroid-cardiac axis in cardiometabolic health susceptibility.

Assessment of causal association between thyroid function and lipid metabolism: a Mendelian randomization study.

BACKGROUND: Thyroid dysfunction is associated with cardiovascular diseases. However, the role of thyroid function in lipid metabolism remains partly unknown. The present study aimed to investigate the causal association between thyroid function and serum lipid metabolism via a genetic analysis termed Mendelian randomization (MR). METHODS: The MR approach uses a genetic variant as the instrumental variable in epidemiological studies to mimic a randomized controlled trial. A two-sample MR was performed to assess the causal association, using summary statistics from the Atrial Fibrillation Genetics Consortium (n = 537,409) and the Global Lipids Genetics Consortium (n = 188,577). The clinical measures of thyroid function include thyrotropin (TSH), free triiodothyronine (FT3) and free thyroxine (FT4) levels, FT3:FT4 ratio and concentration of thyroid peroxidase antibodies (TPOAb). The serum lipid metabolism traits include total cholesterol (TC) and triglycerides, high-density lipoprotein, and low-density lipoprotein (LDL) levels. The MR estimate and MR inverse variance-weighted method were used to assess the association between thyroid function and serum lipid metabolism. RESULTS: The results demonstrated that increased TSH levels were significantly associated with higher TC (ß = 0.052, P = 0.002) and LDL (ß = 0.041, P = 0.018) levels. In addition, the FT3:FT4 ratio was significantly associated with TC (ß = 0.240, P = 0.033) and LDL (ß = 0.025, P = 0.027) levels. However, no significant differences were observed between genetically predicted FT4 and TPOAb and serum lipids. CONCLUSION: Taken together, the results of the present study suggest an association between thyroid function and serum lipid metabolism, highlighting the importance of the pituitary-thyroid-cardiac axis in dyslipidemia susceptibility.