The Effect of Green Coffee Bean Extract on Cardiovascular Risk Factors: A Systematic Review and Meta-analysis

BACKGROUND AND AIM

Cardiovascular disease remains the primary cause of noncommunicable disease- related death. The present systematic review and meta-analysis was performed to assess the possible benefit of the green coffee bean extract on cardio-metabolic markers.

METHODS

PubMed, Scopus, Web of Science, and Cochrane Library were systematically searched to identify clinical trials that examined the effect of green coffee bean extract on cardio-metabolic risk factors including serum lipid profiles, glycemic status-related markers, blood pressure, and anthropometric indices. Since the included RCTs were carried out in different settings, random effect models were used to conduct all meta-analyses.

RESULTS

Fifteen studies (19 arms) consisting of 637 participants were included. The results indicated that green coffee bean extract significantly reduced levels of total cholesterol (-5.93 mg/dl; 95% CI: -9.21, -2.65; I²: 0%), fasting plasma glucose (-2.21 mg/dl; 95% CI: -3.94, -0.48; I²: 32%), systolic blood pressure (-3.08 mmHg; 95% CI: -4.41, -1.75; I²: 26%), diastolic blood pressure (-2.27 mmHg; 95% CI: -3.82, -0.72; I²: 61%), body weight (-1.24 kg; 95% CI: -1.82, -0.66; I²: 15%), and BMI (-0.55 kg/m²; 95% CI: -0.88, -0.22; I²: 73%). Although the pooled effect size of LDL-C, fasting insulin, and waist circumstance were significant, the results were significantly influenced by individual studies. No significant effect was detected for triglycerides, HDL-C, HbA1C, and HOMA-IR. However, the nonsignificant pooled effect size for triglyceride levels was influenced by one individual study.

CONCLUSION

The present study suggests that green coffee been extract consumption can improve total cholesterol, triglycerides, body weight, blood pressure, and fasting plasma glucose.

Effect of green coffee bean extract supplementation on liver function and inflammatory biomarkers: A meta-analysis of randomized clinical trials

Inflammation is considered a major contributor to non-alcoholic fatty liver disease (NAFLD) and several chronic diseases such as, cardiovascular disease and type two diabetes. Green coffee bean extract (GCBE) supplementation has been suggested to enhancing antioxidant capacity in people with obesity but results across studies are mixed. We conducted a meta-analysis of randomized controlled trials of GCBE supplementation in overweight/obese with normal liver function and NAFLD adults with ALT, AST, γ-GTP, ALP, LDH, CRP, IL-6, and TNF-α as outcomes by searching PubMed and other databases. Eight studies were included, totaling 330 participants randomized to GCBE supplementation or placebo ranging from 50 mg/day to 1200 mg/day for 8-12 weeks. GCBE supplementation resulted in lower levels of TNF-α (mean difference = 1.37 pg/mL [95% CI = 0.97-1.76]; p < 0.00001). No significant difference was found in the remaining markers. In conclusion, GCBE supplementation attenuated TNF-α, a circulating inflammatory marker mediator which may be linked with lower systemic inflammation. However, potential cellular and molecular mechanisms by which GCBE exerts this positive effect warrants further investigations in human model studies.

The effects of green coffee extract supplementation on glycemic indices and lipid profile in adults: a systematic review and dose-response meta-analysis of clinical trials

Background

The role of coffee consumption in the risk of cardiovascular diseases has been debated for many years. The current study aimed to summarize earlier evidence on the effects of green coffee extract (GCE) supplementation on glycemic indices and lipid profile.

Methods

We searched available online databases for relevant clinical trials published up to October 2019. All clinical trials investigating the effect of GCE supplementation, compared with a control group, on fasting blood glucose (FBG), serum insulin, total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL), and high-density lipoprotein (HDL) were included. Overall, 14 clinical trials with a total sample size of 766 participants were included in the current meta-analysis.

Results

We found a significant reducing effect of GCE supplementation on FBG (weighted mean difference (WMD): -2.35, 95% CI: − 3.78, − 0.92 mg/dL, P = 0.001) and serum insulin (WMD: -0.63, 95% CI: − 1.11, − 0.15 μU/L, P = 0.01). With regard to lipid profile, we observed a significant reduction only in serum levels of TC following GCE supplementation in the overall meta-analysis (WMD: -4.51, 95% CI: − 8.39, − 0.64, P = 0.02). However, subgroup analysis showed a significant reduction in serum TG in studies enrolled both genders. Also, such a significant reduction was seen in serum levels of LDL and HDL when the analyses confined to studies with intervention duration of ≥8 weeks and those included female subjects. In the non-linear dose-response analyses, we found that the effects of chlorogenic acid (CGA) dosage, the main polyphenol in GCE, on FBG, TG and HDL were in the non-linear fashions.

Conclusion

In conclusion, we found that GCE supplementation improved FBG and serum levels of insulin and TC. Also, there was a significant improvement in other markers of lipid profile in some subgroups of clinical trials.

The effect of green coffee extract supplementation on cardio metabolic risk factors: a systematic review and meta-analysis of randomized controlled trials

Purpose

Considering the present controversies on the association between green coffee supplementation and cardio metabolic risk factors, this systematic review and meta-analysis was conducted to evaluate the effect of green coffee supplementation on cardio metabolic risk factors.

Method

A systematic literature search was performed throughout the PubMed, Embase, Scopus, and Web of Science databases up to October 2019. As a result, all randomized controlled trials over the effect of green coffee supplementation on fasting blood sugar (FBS), insulin, triglyceride, high-density lipoprotein (HDL), low-density lipoprotein (LDL), C - reactive protein (CRP), and homeostatic model assessment for insulin resistance (HOMA-IR) in adults were examined. Data were extracted from the relevant studies and analyzed using the random-effect or pooled model and standardized mean difference (SMD) with 95% confidence interval (CI).

Results

After excluding the irrelevant articles, 27 studies were included in the final analysis. Pooled results revealed that green coffee supplementation significantly reduced FBS (WMD = -2.28, 95% CI: -4.49 to -0.07, P = 0.043), insulin (WMD = -0.53, 95% CI: -0.93 to -0.14, P = 0.008), and triglyceride (WMD = -9.28, 95% CI: -14.93 to - 3.63, P = 0.001). Furthermore, green coffee supplementation increased the HDL levels (WMD = 1.33, 95% CI: 0.08 to 2.58, P = 0.037). However, the changes in HOMA-IR, LDL, and CRP levels were not significant (P > 0.05).

Conclusion

This meta-analysis indicated that green coffee supplementation significantly decreased FBS, insulin, and triglyceride, but improved HDL. No statistically significant improvement was found in HOMA-IR, LDL, and CRP indices following the green coffee supplementation.

The effect of green coffee extract supplementation on anthropometric measures in adults: A comprehensive systematic review and dose-response meta-analysis of randomized clinical trials

BACKGROUND AND AIM

Two meta-analyses summarized data on the effects of green coffee extract (GCE) supplementation on anthropometric measures. However, the accuracy of those meta-analyses is uncertain due to several methodological limitations. Therefore, we aimed to conduct a comprehensive systematic review and dose-response meta-analysis to summarize all available evidence on the effects of GCE supplementation on anthropometric measures by considering the main limitations in the previous meta-analyses.

METHODS

We searched available online databases for relevant publications up to January 2020, using relevant keywords. All randomized clinical trials (RCTs) investigating the effects of GCE supplementation, compared with a control group, on anthropometric measures [including body weight, body mass index (BMI), body fat percentage, waist circumference (WC) and waist-to-hip ratio (WHR)] were included.

RESULTS

After identifying 1871 studies from our initial search, 15 RCTs with a total sample size of 897 participants were included in the systematic review and meta-analysis. We found a significant reducing effect of GCE supplementation on body weight (weighted mean difference (WMD): -1.23, 95 % CI: -1.64, -0.82 kg,P < 0.001), BMI (WMD: -0.48, 95 % CI: -0.78, -0.18 kg/m², P = 0.001), and WC (WMD: -1.00, 95 % CI: -1.70, -0.29 cm, P = 0.006). No significant effect of GCE supplementation on body fat percentage and WHR was seen. In the dose-response analyses, there was no significant association between chlorogenic acid (CGA) dosage, as the main polyphenol in green coffee, and changes in anthropometric measures.

CONCLUSION

We found that GCE supplementation had a beneficial effect on body weight, BMI and WC. It provides a cost-effective and safe alternative for the treatment of obesity. Additional well-designed studies are required to further confirm our findings.

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 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.

Effect of Coffee Consumption on the Progression of Type 2 Diabetes Mellitus among Prediabetic Individuals

BACKGROUND

A previous large-scale cohort study investigated the relationship between coffee intake and the progression of diabetes mellitus in the United States. However, studies on the effects of coffee on diabetes are rare in South Korea. Therefore, this study assessed the amount and method of coffee intake in Koreans in order to determine if coffee intake has a prophylactic effect on diabetes progression.

METHODS

This study included 3,497 prediabetic patients from a single medical institution, with glycated hemoglobin levels ranging from 5.7% to 6.4%. Cross-tabulation and Kaplan-Meier survival analyses were performed to compare patients with and without diabetes progression based on the frequency and method of coffee intake. Cox proportional hazard analysis was performed to correct for confounding variables.

RESULTS

The observation period (mean±standard deviation) was 3.7±2.3 years. Kaplan-Meier survival analysis revealed that the risk of diabetes progression was lowest in patients who drank black coffee three or more times per day (P=0.036). However, correction for confounding variables in Cox proportional hazard analysis revealed that, while the risk was lower for the patients who typically consumed black coffee than for those who mixed creamer and sugar into their coffees, the difference was not significant.

CONCLUSION

The results of this study suggest that drinking coffee without sugar and creamer at least three times daily has the greatest preventive effect on diabetes onset.