The effect of fasting and energy restricting diets on markers of glucose and insulin controls: a systematic review and meta-analysis of randomized controlled trials.

Inconsistencies exist with regard to influence of fasting and energy-restricting diets on markers of glucose and insulin controls. To address these controversial, this study was conducted to determine the impact of fasting diets on fasting blood sugars (FBSs), insulin, homeostatic model assessment insulin resistance (HOMA-IR) and hemoglobin A1c (HbA1c) levels. A comprehensive systematic search was carried out in electronic databases, i.e., Scopus, PubMed, and Web of Science through June 2019 for RCTs that investigated the impact of fasting and energy-restricting diets on circulating FBS, insulin, HOMA-IR and HbA1c levels from. Weighted mean difference (WMD) with the 95% CI were used for estimating combined effect size. The subgroup analysis was applied to specify the source of heterogeneity among articles. Pooled results from 30 eligible articles with 35 arms demonstrated a significant decrease in FBS (WMD): -3.376 mg/dl, 95% CI: -5.159, -1.594, p < 0.001), insulin (WMD: -1.288 µU/ml, 95% CI: -2.385, -0.191, p = 0.021), HOMA-IR (WMD: -0.41 mg/dl, 95% CI: -0.71, -0.10, p = 0.01) levels following fasting or energy-restricting diets. Nevertheless, no significant changes were observed in serum HbA1c levels. The subgroup analyses showed that overweight or obese people with energy restricting diets and treatment duration >8 weeks had a greater reduction in FBS, insulin and HOMA-IR level compared with other subgroups. The evidence from available studies suggests that the fasting or energy-restricting diets leads to significant reductions in FBS, insulin and HOMA-IR level and has modest, but, non-significant effects on HbA1c levels.

The Influence of Fasting and Energy Restricting Diets on Blood Pressure in Humans: A Systematic Review and Meta-Analysis.

INTRODUCTION: To the best of our knowledge, no comprehensive meta-analysis has been carried out to investigate the effect of different approaches of fasting and calorie restriction on blood pressure.  AIM: Thus, the present systematic review and meta-analysis was designed to examine the effect of fasting and energy restricting diets on blood pressure in adult subjects. METHODS: We searched PubMed/Medline, Scopus, the Cochrane Library, and Google Scholar up to June 2019. The clinical trials that examined the effects of fasting and energy restricting diets on Blood Pressure was identified using MESH and non-MESH terms. RESULTS: 23 studies, including a total of 1397 participants, reported SBP and DBP as an outcome measure. Overall results from the random-effects model indicated that fasting and energy restricting administration elicited significant changes in SBP (weight mean difference (WMD): - 1.88 mmHg, 95% CI - 2.50, - 1.25) and DBP (WMD - 1.32 mmHg, 95% CI - 1.81, - 0.84, p = 0.000). Subgroup analyses displayed that intervention duration ≤ 12 weeks more effectively reduced SBP (WMD: -3.26 mmHg) and DBP (WMD - 1.32 mmHg). In addition, these analyses showed that fasting regimens (WMD - 3.26 mmHg) more effectively reduced SBP than energy restricting diets (WMD - 1.09 mmHg). CONCLUSION: The principal finding of this study was that fasting and energy restricting diets elicited, overall, significant reductions in SBP and DBP. Subsequent subgroup analyses revealed that intervention duration ≤ 12 weeks and fasting regimens more effectively reduced SBP and DBP.

Effects of walnut intake on anthropometric characteristics: A systematic review and dose-response meta-analysis of randomized controlled trials.

BACKGROUND & OBJECTIVE: Effects of walnut intake on anthropometric measurements have been inconsistent among clinical studies. Thus, we conducted a meta-analysis of randomized clinical trials (RCTs) to evaluate and quantify the effects of walnut intake on anthropometric characteristics. METHODS: We carried out a systematic search of all available RCTs up to June 2019 in the following electronic databases: PubMed, Scopus, Web of Science and Google Scholar. Pooled weight mean difference (WMD) of the included studies was estimated using random-effects model. RESULTS: A total of 27 articles were included in this meta-analysis, with walnuts dosage ranging from 15 to 108 g/d for 2 wk to 2 y. Overall, interventions with walnut intake did not alter waist circumference (WC) (WMD: -0.193 cm, 95 % CI: -1.03, 0.64, p = 0.651), body weight (BW) (0.083 kg, 95 % CI: -0.032, 0.198, p = 0.159), body mass index (BMI) (WMD: -0.40 kg/m,295 % CI: -0.244, 0.164, p = 0.703), and fat mass (FM) (WMD: 0.28 %, 95 % CI: -0.49, 1.06, p = 0.476). Following dose-response evaluation, reduced BW (Coef.= -1.62, p = 0.001), BMI (Coef.= -1.24, p = 0.041) and WC (Coef.= -5.39, p = 0.038) were significantly observed through walnut intake up to 35 g/day. However, the number of studies can be limited as to the individual analysis of the measures through the dose-response fashion. CONCLUSIONS: Overall, results from this meta-analysis suggest that interventions with walnut intake does not alter BW, BMI, FM, and WC. To date, there is no discernible evidence to support walnut intake for improving anthropometric indicators of weight loss.

The influence of green coffee bean extract supplementation on blood glucose levels: A systematic review and dose-response meta-analysis of randomized controlled trials.

Studies regarding the influence of green coffee extract (GCE) on blood glucose levels are conflicting. Thus, we sought to conduct a meta-analysis and systematic review of all available randomized controlled trials (RCTs) to quantify the effects of GCE and CGA intervention on blood glucose and insulin levels. We performed systematic online searches in Scopus, Web of science, and PubMed databases, from inception to July 2019. Data were combined analyzed using a random effects model (Der Simonian-Laird method) and reported as weighted mean differences (WMD). Ten trials reported the influences of GCE on FBS and insulin and were subsequently entered into the meta-analysis. Combined results highlighted that FBS was significantly altered after GCE consumption (WMD: -1.791 mg/dl, 95% CI -3.404, -0.177), with no significant heterogeneity among the studies (I2 = 35.0%, p = .128). However, overall results demonstrated that GCE administration did not result in any significant alteration in insulin levels (WMD: -0.925 µU/ml, 95% CI:-1.915, 0.064), with significant heterogeneity found across studies (I2 = 87.9%). In sub-group analysis, insulin levels were significantly reduced when GCE was supplemented in dosages of ≥400 mg/day (WMD:-1.942 mg/dl, 95% CI:-1.184, -0.975; I2 = 0.0%). The results of present study support the use of GCE for the enhancement of blood glucose, while subgroup analysis highlighted significant improvements in insulin levels when GCE is supplemented in doses ≥400 mg/day.

The effects of green coffee bean extract supplementation on lipid profile in humans: A systematic review and meta-analysis of randomized controlled trials.

BACKGROUND AND AIM: This systematic review and meta-analysis aimed to assess the effects of green coffee bean extract (GCBE) supplementation on lipid profile in adults. METHODS AND RESULTS: The PubMed/Medline, Scopus, Web of sciences, and Google Scholar were systematically searched for randomized controlled trials available in English and published before February 2019. The meta-analysis was conducted using fixed effects models, and between-study heterogeneity was assessed by Cochran's Q test and I2. A total of 17 effect sizes were included in the meta-analysis. Combined effect sizes on serum total cholesterol concentrations revealed significant effects of GCBE supplementation on serum total cholesterol [weighted mean difference (WMD): -4.51 mg/dL, 95% confidence interval (CI): -6.89, -2.12, p < 0.001], low density lipoprotein-cholesterol (LDL-C) (WMD: -4.38 mg/dL, 95% CI: -6.44, -2.31, p < 0.001), and high density lipoprotein-cholesterol (HDL-C) (WMD: 2.63 mg/dL, 95% CI: 2.20, 3.07, p < 0.001) compared to controls. Nevertheless, no significant changes were observed in serum triglycerides levels (WMD: -4.34 mg/dL, 95% CI: -9.00, 0.32, p = 0.068). CONCLUSION: The evidence from available studies suggests that the GCBE supplementation leads to significant reductions in total cholesterol, HDL-C, and LDL-C levels, and has modest, but, non-significant effects on triglycerides levels.

The effect of green coffee extract supplementation on blood pressure: A systematic review and meta-analysis of randomized controlled trials.

Given the proliferation in studies investigating green coffee bean extract (GCBE) supplementation, the purpose of this study was to determine the efficacy and effectiveness of GCBE supplementation on indices of blood pressure. The literature search was performed in four databases, namely, PubMed/Medline, Scopus, the Cochrane Library, and Google Scholar, to identify clinical trials that examined the effects of green coffee supplements on systolic blood pressure (SBP) and diastolic blood pressure (DBP) up to February 2019. Mean change and standard deviation (SD) of the outcome measures were used to estimate the mean difference between the intervention group and the control group at follow-up. Nine studies reported SBP and DBP as an outcome measure. Results revealed significant reduction in SBP (weighted mean difference: -3.093 mmHg, 95% confidence interval [CI]: -3.914, -2.273; I2 = 0.0%) and DBP (-2.170 mmHg, 95% CI: -2.749, -1.590; I2 = 46.5%) after green coffee supplementation with low heterogeneity among the studies. In addition, in subgroup analysis, a significant reduction in SBP and DBP in studies with hypertensive patients, green coffee dosage <400 mg, and administered for 4 weeks was identified. The results of the current meta-analysis study support the use of GCBE supplementation for the improvement of blood pressure indices, with subgroup analysis highlighting improvements in hypertensive patients.

The effect of green-coffee extract supplementation on obesity: A systematic review and dose-response meta-analysis of randomized controlled trials.

BACKGROUND: Given that the most recent systematic review investigating Green-Coffee Extract (GCE) as a weight loss facilitator was nearly a decade ago and that the authors reported there no consensus on the effect of GCE/CGA (Chlorogenic acids) on body composition indices, a comprehensive systematic review and dose-response meta-analysis of all available randomized controlled trial (RCTs) was undertaken to examine the effect of GCE and CGA intervention on body weight (BW), body mass index (BMI) and waist circumference (WC) in adults. METHODS: We conducted a systematic search of all available randomized controlled trials (RCTs) performed up to June 2019 in the following electronic databases: PubMed, Scopus and Google Scholar. RCTs that investigated the effect GCE/CGA Supplementation on BW, BMI and WC in adults were included for final analysis. The pooled weight mean difference (WMD) of included studies was estimated using a random-effects model. RESULTS: A total of 13 articles with 16 RCTs were included in the meta-analysis. Results revealed significant reduction in BMI (WMD: -0.403 kg/m2, 95% CI: -0.800, -0.005, p = 0.047) and no significant change in BW (WMD: -0.585 kg, 95% CI: -1.498, 0.329, p = 0.210) and WC (WMD: -0.847 cm, 95% CI: -1.764, 0.071, p = 0.070). In the subgroup analysis, studies that were conducted on baseline BMI ≥25 kg/m2 revealed a significant greater reduction in body weight and BMI than those performed on baseline BMI <25 kg/m2. Moreover, short supplementation periods of less than 4 weeks had no effect. CONCLUSION: The results of current meta-analysis study support the use of GCE supplementation for the improvement of obesity indices, with sub-group analysis highlighting greater improvements in individuals with a starting BMI ≥25 kg/m2.

The effect of L-carnitine supplementation on serum leptin concentrations: a systematic review and meta-analysis of randomized controlled trials.

PURPOSE: The actual effects of L-carnitine administration on leptin serum level is inconsistent. In order to assess the efficacy of L-carnitine supplementation on serum leptin we conducted a meta-analysis of randomized controlled trials (RCTs). METHODS: Seven studies with 325 cases and 330 controls were included. The pooled weighted mean difference (WMD) was calculated by random-effects model. The heterogeneity across studies was evaluated by using Cochrane's Q and I2 tests. In addition, we carried out the metaninf command to test the effect of each individual study on the overall result. RESULTS: L-carnitine supplementation seemed to have no significant effect on serum leptin concentrations (WMD: -0.565 ng/mL; 95% CI: -2.417 to 1.287, p = 0.550). However, between-study heterogeneity was higher across all studies (I2 = 84.3%, p < 0.0001). Subgroup analysis to find the sources of heterogeneity showed that L-carnitine dosage (g) ( < 2 g: I2 = 00.0%, p = 0.408), and study population (diabetes: I2 = 46.7%, p = 0.153, and non-diabetes: I2 = 15.1%, p = 0.317) were the potential sources of heterogeneity. Besides, a more significant reduction in serum leptin concentration was observed with a daily dose of ≥ 2 mg L-carnitine (WMD: -2.742 ng/mL; 95% CI: -3.039 to -2.444, p < 0.001), in diabetic patients (WMD: -2.946 ng/mL; 95% CI: -3.254 to -2.638, p < 0.001), and with intervention duration <12 weeks (WMD: -2.772 ng/mL; 95% CI: -3.073 to -2.471, p < 0.001). CONCLUSION: L-carnitine consumption does not reduce serum leptin significantly. However, a significant effect on leptin was observed in diabetic patients and patients who received doses more than 3 mg per day in the course of <12 weeks.