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

Plant-Derived Natural Products for Dietary Intervention in Overweight and Obese Individuals: A Systematic Review and Network Meta-Analysis

Growing rates of overweight and obesity worldwide call for novel approaches to treatment, and plant-derived natural products present a promising therapeutic option. Evaluate the efficacy of plant-derived natural products as dietary interventions for overweight and obesity through a systematic review and network meta-analysis. We conduct a systematic review and network meta-analysis following PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines. We searched from five databases and registries up to March 2024, selecting randomized controlled trials examining dietary interventions with plant-derived natural products for adults with obesity or overweight. The frequentist approach was used for the network meta-analysis, assessing 13 metabolic and obesity-related outcomes. Our review included 39 studies with 2513 participants with PROSPERO registration ID CRD42024520305. African Mango emerged as the most effective intervention, reducing body weight (MD: -10.00 kg, 95% CI: -16.74 to -3.26), waist circumference (MD: -11.70 cm, 95% CI: -17.15 to -6.25), total cholesterol (MD: -44.01 mg/dL, 95% CI: -58.95 to -29.08), triglycerides (MD: -42.65 mg/dL, 95% CI: -79.70 to -5.60), and random blood glucose (MD: -14.95 mg/dL, 95% CI: -18.60 to -11.30). Green coffee led to the largest reduction in body fat percentage (MD: -2.90%, 95% CI: -4.88 to -0.92) and BMI (MD: -3.08 kg/m2, 95% CI: -6.35 to 0.19). Ephedra was most effective in reducing fasting blood glucose (MD: -4.60 mg/dL, 95% CI: -5.49 to -3.71) and HOMA-IR (MD: -16.20, 95% CI: -18.66 to -13.74). There were too few direct comparisons between various metabolites; thus, most of the comparisons were indirect comparisons through placebo. Plant-derived natural products significantly impact obesity management, notably in body weight, waist circumference, and lipid profile reduction; however, further high-quality and rigorous studies were needed to establish the clinical efficacy of the plant-derived natural products.

Effects of green coffee supplementation on paraoxonase-1 activity and malondialdehyde levels in Iranian women with polycystic ovary syndrome: a randomized clinical trial

BACKGROUND

Polycystic ovary syndrome (PCOS) is a common, heterogeneous clinical syndrome affecting women. Investigating oxidative stress in women is crucial, as it is linked to insulin resistance and endothelial dysfunction. Chlorogenic acid, a bioactive component found in green coffee, has numerous documented health benefits. This study aimed to assess the beneficial effects of green coffee consumption on paraoxonase-1 (PON-1) activity and malondialdehyde (MDA) levels in women with PCOS.

METHODS

This study was a double-blind randomized clinical trial that included 44 patients with PCOS. Participants were randomly assigned to either the intervention or control group. For 6 weeks, the intervention group (n=22) received 400 mg of green coffee supplements, while the control group (n=22) received 400 mg of a starch-based placebo. Anthropometric indices, dietary assessments, and physical activity levels were evaluated before and after the 6-week intervention period. Additionally, blood samples were collected for laboratory analysis.

RESULTS

Supplementation with green coffee increased PON-1 levels by 3.5 units, a significant finding (p=0.038). Additionally, the intake of green coffee supplements significantly reduced blood cholesterol levels by 18.8 units (p=0.013) and triglyceride levels by 6.1 units (p=0.053). However, no significant differences were observed in the levels of MDA, high-density lipoprotein, low-density lipoprotein, fasting blood sugar, insulin, or homeostatic model assessment of insulin resistance as a result of the intervention.

CONCLUSION

Supplementation with green coffee alters PON-1 activity and cholesterol levels in women with PCOS. However, it has no significant impact on MDA levels or glycemic status.

The impact of coffee consumption on human health

Coffee consumption is a key aspect of modern lifestyle. Caffeine, the major component of coffee, has an impact on various human tissues and organs after being absorbed in the gastrointestinal tract. Its beneficial effects on reducing both the incidence of many diseases, including cancer, and overall mortality has been described. According to most cohort studies, coffee has a positive impact on cardiovascular diseases as it lowers the risk of cardiovascular diseases and does not increase blood pressure. Meta-analyses suggest a protective effect of caffeine contained in coffee on neurological disorders such as migraines, dementia, and slowing the progression of Alzheimer’s disease and Parkinson’s disease. However, research on malignant tumour development in humans is inconsistent. On the one hand, caffeine contained in coffee has been shown to significantly reduce the risk of breast cancer, endometrial cancer and prostate cancer. On the other hand, most meta-analyses have shown an association between coffee intake and an increased prevalence of lung cancer. In some cases, it can even lead to significant rise in morbidity. The positive impact of chlorogenic acid (a polyphenol in coffee) administered with doxorubicin has been described in in vitro and in vivo lung cancer studies.

The effects of green coffee bean extract on blood pressure and heart rate: A systematic review and dose-response meta-analysis of randomized controlled trials

BACKGROUND AND AIMS

The existing literature on the effects of green coffee bean extract (GCBE) consumption on systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) is equivocal. This study aimed to summarize the effects of GCBE consumption on SBP, DBP and HR in adults.

METHODS

Data were pooled using a random-effects model and expressed as weighted mean difference (WMD) and 95 % confidence intervals (95 % CIs).

RESULTS

Out of 1624 records, 10 studies that enrolled 563 participants were included. GCBE consumption significantly decreased SBP (WMD: -2.95 mmHg; 95 % CI: -4.27 to -1.62; p < 0.001) and DBP (WMD: -2.15 mmHg; 95 % CI: -2.59 to -1.72; p < 0.001). However, there was no significant effect on HR (WMD: -1.20 bpm; CI: -2.93 to 0.51; p = 0.170). Subgroup analysis showed that GCBE consumption had a more significant effect on SBP and DBP in participants with high SBP and DBP and had no effect on blood pressure in females. Linear and non-linear dose-response analyses were conducted to find the optimum GCBE dosage and duration of intervention. However, no significant associations were observed for SBP, DBP, and HR in linear meta-regression and non-linear dose-response based on the dose and duration of the intervention.

CONCLUSION

GCBE has the potential as a hypertension-reducing supplement in hypertensive patients. However, GCBE did not significantly change HR.

Associations between Chronic Medical Conditions and Persistent Dietary Supplement Use: The US Military Dietary Supplement Use Study

This longitudinal study examined associations between chronic medical conditions (CMCs) and persistent dietary supplement (DS) use. On two separate occasions, 1.3 ± 0.2 years apart, military service members (SMs) (n = 5778) completed identical questionnaires concerning their DS use in the past 6 months and their demographic and lifestyle characteristics. Medical conditions were obtained from a medical surveillance system six months before the first questionnaire and during the period between questionnaires. Diagnoses were grouped into 19 major (largely systemic) and 9 specific CMCs. Conditions diagnosed in both periods (CMCs) were examined in relation to DS use reported on both questionnaires (persistent DS use). After adjustment for demographic and lifestyle factors, higher odds of persistent DS use were found in 7 of the 19 major CMCs and 5 of the 9 specific CMCs. SMs with a CMC had 1.25 (95% confidence interval [95%CI] = 1.10-1.41) higher adjusted odds of persistent DS use. The three specific CMCs with the highest adjusted odds of persistent DS use were anxiety (odds ratio [OR] = 2.30, 95%CI = 1.36-3.89), depression (OR = 2.12, 95%CI = 1.20-3.73), and gastroesophageal reflux disease (OR = 2.02, 95%CI = 1.02-4.04). Among DS categories, participants with a CMC had higher adjusted odds of persistent vitamins or mineral use (OR = 1.31, 95% CI = 1.12-1.53). Participants with CMCs had a higher prevalence of persistent DS use, especially individual vitamin and mineral use.

Dietary supplements: clinical cholesterol-lowering efficacy and potential mechanisms of action

This review aims to analyse the efficacy of dietary supplements in reducing plasma cholesterol levels. Focusing on evidence from meta-analyses of randomised controlled clinical trials, with an emphasis on potential mechanisms of action as supported by human, animal, and cell studies. Certain dietary supplements including phytosterols, berberine, viscous soluble dietary fibres, garlic supplements, soy protein, specific probiotic strains, and certain polyphenol extracts could significantly reduce plasma total and low-density lipoprotein (LDL) cholesterol levels by 3-25% in hypercholesterolemic patients depending on the type of supplement. They tended to be more effective in reducing plasma LDL cholesterol level in hypercholesterolemic individuals than in normocholesterolemic individuals. These supplements worked by various mechanisms, such as enhancing the excretion of bile acids, inhibiting the absorption of cholesterol in the intestines, increasing the expression of hepatic LDL receptors, suppressing the activity of enzymes involved in cholesterol synthesis, and activating the adenosine monophosphate-activated protein kinase signalling pathway.

The effect of phytosterol supplementation on lipid profile: A critical umbrella review of interventional meta-analyses

Despite multiple investigations assessing the impact of phytosterol supplementation on serum lipid levels, there is still a great deal of debate regarding the benefits of this intervention in the management of dyslipidemia. Therefore, we aimed at clarifying this dilemma by conducting the present umbrella review of interventional meta-analyses. Scopus, PubMed, Web of Science, and EMBASE were used to search for pertinent publications on the effect of phytosterol supplementation on the lipid profile in humans up to June 2023. To compute the overall effect size (ES) and confidence intervals (CI), the random-effects model was used. The I2 statistic and Cochrane's Q-test were applied to estimate the heterogeneity among the studies. Seventeen meta-analyses with 23 study arms were included in the umbrella meta-analysis. Data pooled from the 23 eligible arms revealed that phytosterol supplementation reduces low-density lipoprotein cholesterol (LDL-C) (ES = -11.47 mg/dL; 95% CI: -12.76, -10.17, p < 0.001), total cholesterol (TC) (ES = -13.02 mg/dL; 95% CI: -15.68, -10.37, p < 0.001), and triglyceride (TG) (ES = -3.77 mg/dL; 95% CI: -6.04, -1.51, p = 0.001). Subgroup analyses showed that phytosterol administration with dosage ≥2 g/day and duration over 8 weeks and in hypercholesterolemic subjects was more likely to decrease LDL-C, TC, and TG. Phytosterol administration did not significantly modify HDL-C (ES = 0.18 mg/dL; 95% CI: -0.13, -0.51, p = 258) levels when compared to controls. The present umbrella meta-analysis confirms that phytosterol administration significantly reduces LDL-C, TC, and TG, with a greater effect with doses of ≥2 g/day and treatment duration >8 weeks, suggesting its possible application as a complementary therapy for cardiovascular risk reduction. Further studies are needed to determine the efficacy of phytosterols in patients with specific health conditions, as well as to ascertain the adverse effects, the maximum tolerable dose, and the maximum recommended duration of phytosterol administration.

Chlorogenic acid in green bean coffee on body weight: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Supplemental green bean coffee extract (GBCE) with caffeine has been shown to prevent weight gain. There are different dosages of GBCE that contain chlorogenic acid (CGA), and the data for their effectiveness in preventing weight gain (500 mg/day) is currently out of date. To better understand the effects of GBCE containing CGA on body weight, the present study sets out to perform a systematic review and meta-analysis of these studies.

METHODS

Using electronic databases, including Scopus, Embase, PubMed, and Cochrane Library databases, literature was searched up to October 13, 2022. For the meta-analysis examining the impact of GBCE containing CGA (500 mg/day) on body weight with a random-effects model, the randomized controlled trials (RCTs) were considered. We calculated weighted mean differences and 95% confidence intervals (CIs). To gauge study heterogeneity, the Cochran Q statistic and I-squared tests (I2) were employed.

RESULTS

The meta-analysis includes three RCTs with 103 individuals (case = 51, control = 52). The combined findings of GBCE with CGA at least 500 mg/day result in body weight reduction (WMD: - 1.30 and 95% CI: - 2.07 to - 0.52, p = 0.001) without study heterogeneity (I2 = 0%, p = 0.904) and without publication bias estimated using Egger's and Begger's test (p = 0.752 and p = 0.602, respectively).

CONCLUSIONS

According to the meta-analysis, GBCE with CGA 500 mg/day lowers body weight. Nevertheless, despite its limited sample size and short-term study, this study was successful. Long-term research on the effectiveness and safety of GBCE and CGA on body weight require more clinical trials.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42021254916.

The effects of green tea supplementation on cardiovascular risk factors: A systematic review and meta-analysis

Purpose

A bulk of observational studies have revealed the protective role of green tea supplementation in cardiovascular diseases. The current systematic review and meta-analysis study aimed to establish the effects of green tea supplementation on cardiovascular risk factors including lipid profile, blood pressure, glycemic control markers and CRP.

Methods

A systematic literature search of randomized clinical trials (RCTs) that investigated the effects of green tea supplementation and cardiovascular risk factors was undertaken in online databases including PubMed/Medline, Scopus, Web of Science, and Embase using a combination of green tea and cardiovascular risk factors search terms. Meta-analyses were carried out using a random-effects model. The I2 index was used to assess the heterogeneity of RCTs.

Results

Among the initial 11,286 studies that were identified from electronic databases search, 55 eligible RCTs with 63 effect sizes were eligible. Results from the random effects meta-analysis showed that GTE supplementation significantly reduced TC (WMD = -7.62; 95% CI: -10.51, -4.73; P = < 0.001), LDL-C (WMD = -5.80; 95% CI: -8.30, -3.30; P = < 0.001), FBS (WMD = -1.67; 95% CI: -2.58, -0.75; P = < 0.001), HbA1c (WMD = -0.15; 95% CI: -0.26, -0.04; P = 0.008), DBP (WMD = -0.87; 95% CI: -1.45, -0.29; P = 0.003), while increasing HDL-C (WMD = 1.85; 95% CI: 0.87, 2.84; P = 0.010). Subgroup analyses based on the duration of supplementation (≥ 12 vs. < 12 weeks), dose of green tea extract (GTE) (≥1,000 vs. < 1,000 mg/d), sex (male, female, and both), baseline serum levels of lipid profile, and glycemic control factors demonstrated different results for some risk factors.

Conclusion

The current study suggests improvements in the lipid and glycemic profiles following green tea supplementation. These findings support previous evidence showing the health benefits of green tea supplementation on cardiometabolic risk factors.

Interactive deciphering electron-shuttling characteristics of Coffea arabica leaves and potential bioenergy-steered anti-SARS-CoV-2 RdRp inhibitor via microbial fuel cells

Due to the pandemics of COVID-19, herbal medicine has recently been explored for possible antiviral treatment and prevention via novel platform of microbial fuel cells. It was revealed that Coffea arabica leaves was very appropriate for anti-COVID-19 drug development. Antioxidant and anti-inflammatory tests exhibited the most promising activities for C. arabica ethanol extracts and drying approaches were implemented on the leaf samples prior to ethanol extraction. Ethanol extracts of C. arabica leaves were applied to bioenergy evaluation via DC-MFCs, clearly revealing that air-dried leaves (CA-A-EtOH) exhibited the highest bioenergy-stimulating capabilities (ca. 2.72 fold of power amplification to the blank). Furthermore, molecular docking analysis was implemented to decipher the potential of C. arabica leaves metabolites. Chlorogenic acid (-6.5 kcal/mol) owned the highest binding affinity with RdRp of SARS-CoV-2, showing a much lower average RMSF value than an apoprotein. This study suggested C. arabica leaves as an encouraging medicinal herb against SARS-CoV-2.

Neuroprotective effect of green and roasted coffee bean extracts on cerebral ischemia-induced injury in rats

Stroke is a lethal event with a high incidence in Egypt. Quick early intervention can be lifesaving. Transient global ischemia (TGI), a type of ischemic stroke, is mainly instigated by cardiac arrest. Ischemia followed by reperfusion causes further neuronal cell damage. In this study, we aimed to evaluate the potential apoptotic, anti-inflammatory, and neuroprotective effects of green (GCBE) and roasted (RCBE) coffee bean water extract against transient global ischemia-induced via a bilateral common carotid artery occlusion (CAO) in rats. Before CAO, 1.5 ml/kg body weight/day of GCBE or RCBE was administered for 14 days by oral gavage. Ischemia/reperfusion (I/R) and sham groups were treated with a vehicle. Oxidative stress biomarkers and antioxidant enzyme activities, such as MDA, NO, GSH, SOD, CAT, GR, GPx, inflammatory markers TNF-α, IL-1β, and NF-κB, and BDNF were investigated. Quantitative real-time PCR analysis of mitogen-activated protein kinase pathways, in addition to heme oxygenase 1, and nuclear factor erythroid 2-related factor 2 were determined. Apoptotic markers, including Bcl-2, Bax, and caspase 3, in addition to the vascular endothelial growth factor-a, were investigated, followed by an examination of hippocampal histopathology. Pre-administration of GCBE and RCBE improved neurological function and neuronal survival, suppressed the spread of oxidative stress, inflammation, and apoptosis, and reversed most of the pathological changes. However, green coffee bean extract was more effective than roasted coffee bean extract, perhaps due to the roasting process, which may affect active compounds. In conclusion, GCBE and RCBE represent a potential clinical strategy for pre-ischemic conditioning.

Effects of Flaxseed on Blood Lipids in Healthy and Dyslipidemic Subjects: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

To address hyperlipidemia, flaxseed demonstrates a great impact on experimental and clinical trials. Therefore, the effects of flaxseed on lipid profiles of healthy and dyslipidemic subjects were assayed. The literature search was performed based on English reports of randomized control trials (RCTs) up to April 2021 to seek the effect of flaxseed on lipid profiles of healthy and dyslipidemic subjects. A total of 14 RCTs with 1107 participants were evaluated. Based on results, flaxseed significantly improves the lipid profile in dyslipidemic patients comprising total cholesterol (TC), low-density lipoprotein (LDL-C) and triglyceride (TG) in comparison with the control group. Nevertheless, no significant changes were observed in high-density lipoprotein (HDL-C). Although in healthy individual flaxseed significantly increased HDL-C, LDL-C and TG. Subgroup analysis on healthy subjects showed that flaxseed improved LDL-C on overweight subjects with BMI>25. The evidence suggests that flaxseed significantly improved TC, LDL-C and TG in dyslipidemic subjects and additionally improved the HDL-C on healthy subjects.

The effect of tibolone treatment on lipid profile in women: A systematic review and dose-response meta-analysis of randomized controlled trials

Inconsistencies exist with regard to influence of tibolone treatment on the lipid profile. The reasons for these inconsistencies might derive from several factors, i.e., differences in baseline variables, intervention duration, participants' health status or baseline body mass index (BMI). To address these inconsistencies, based on a systematic search in Scopus, PubMed/Medline, Web of Science, and Embase for papers published until 21 December 2020, we conducted the current dose-response meta-analysis of randomized controlled trials (RCTs) to determine the impact of tibolone treatment on the lipid profile. The overall findings were derived from 26 RCTs. Tibolone administration decreased total cholesterol (TC) (weighted mean difference, WMD: -18.55 mg/dL, CI: -25.95 to -11.16, P < 0.001), high-density lipoprotein-cholesterol (HDL-C) (WMD: -9.42 mg/dL, CI: -11.83 to -7.01, P < 0.001) and triglyceride (TG) (WMD: -21.43 mg/dL, CI: -27.15 to -15.70, P < 0.001) levels. A significant reduction in LDL-C occurred when tibolone was prescribed for ≤ 26 weeks (WMD: -7.64 mg/dL, 95% CI: -14.58 to -0.70, P = 0.031) versus > 26 weeks (WMD: -8.84 mg/dL, 95% CI: -29.98, 12.29, P = 0.412). The decrease in TG (WMD: -22.64 mg/dL) and TC (-18.55 mg/dL) concentrations was more pronounced in patients with BMI ≥ 25 kg/m2versus BMI < 25 kg/m2. This systematic review and meta-analysis discovered that tibolone decreases TC, HDL-C and TG levels. LDL-C concentrations are significantly reduced when tibolone administration lasts for ≤ 26 weeks.

The Impact of Chromium Supplementation on Blood Pressure: A Systematic Review and Dose-Response Meta‑Analysis of Randomized‑Controlled Trials

INTRODUCTION

Potential effects of chromium supplementation on blood pressure (BP) have been examined in several interventional studies. Nevertheless, findings in this context are controversial.

AIM

Therefore, the current systematic review and meta-analysis aimed to comprehensively assess the impact of chromium supplementation on BP.

METHODS

Five online databases including Web of Science, Scopus, Embase, Google Scholar, and PubMed were systematically searched from inception to March 2020. We included all randomized clinical trials (RCTs) evaluating the effects of chromium supplementation on systolic blood pressure (SBP) and/or diastolic blood pressure (DBP) in humans.

RESULTS

The random-effects meta-analysis of 11 eligible RCTs with 637 participants demonstrated the significant decline in both SBP (WMD - 2.51 mmHg; 95% CI - 4.97 to - 0.05, p = 0.04) and DBP (WMD - 1.04 mmHg; 95% CI - 1.96 to - 0.12, p = 0.026) following supplementation with chromium. In subgroup analysis, studies that were administered chromium yeast and brewer's yeast, showed greater decrease in SBP. Also, in stratification based on participants' health status, significant reduction in SBP only was seen in diabetic patients with chronic heart disease (CHD). Nonlinear dose-response analysis revealed a significant influence of chromium dosage on SBP changes.

CONCLUSION

The current meta-analysis, indicated that supplementation with chromium significantly decrease SBP and DBP. In subgroup analysis, administration of chromium yeast and brewer's yeast resulted in greater reduction in SBP. Further large-scale RCTs with better design are needed to confirm these findings.

Green coffee VS dietary supplements: A comparative analysis of bioactive compounds and antioxidant activity

The aim of this work was to assess and compare both the antioxidant potential and content of the selected biologically active substances in green coffee samples and dietary supplements based on green coffee extracts. The newly developed method using HPLC coupled with Corona detector (HPLC-CAD) allowed the analysis of chlorogenic acid, caffeine, caffeic acid, coumaric acid, and ferulic acid in a single run. The method was validated and characterized by a wide concentration range (5-75 μg/mL), sensitivity, accuracy (92.7-112%), repeatability (RSD <5.32%), and precision (1.80-4.04%). The assessment of antioxidant potential was done by the spectrophotometric Folin-Ciocalteu method. Green coffee samples and extract characterized by comparable or, in the case of some samples, even higher antioxidant properties than dietary supplements. There was found a great variety of CGA levels in dietary supplements (0.33-329 mg/g) compared to the green coffee samples (32.7 mg/g - 47.6 mg/g). The highest caffeine content (156 mg/tablet) was determined in one dietary supplement, while green coffee samples contained its lower levels (20.9 mg/g). The quality of some supplements is not satisfactory as their composition does not comply with the manufacturer's declaration. There were found discrepancies between the value determined and declared by the producer (<243%).

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.

The effect of black tea supplementation on blood pressure: a systematic review and dose-response meta-analysis of randomized controlled trials

The main goal of this work was to clarify the effects of black tea supplementation on blood pressure (BP) by performing a systematic review according to the PRISMA (preferred reporting items for systematic reviews and meta-analyses) guidelines, followed by a dose-response meta-analysis of randomized controlled trials (RCTs). Electronic search was carried out in PubMed, Embase and the Cochrane Library databases published up to March 2020. To be included, RCTs had to report the effect of black tea supplementation on systolic blood pressure (SBP) or diastolic blood pressure (DBP) in adults. A total of 13 trials, including 22 study arms were eligible for inclusion in the final quantitative analysis. It was observed that black tea supplementation significantly reduced SBP (WMD - 1.04 mmHg; 95% CI - 2.05 to -0.03; and P = 0.04) and DBP (WMD - 0.59 mmHg; 95% CI - 1.05 to -0.13; and P = 0.01) compared to the control. However, nonlinear analysis failed to indicate a significant influence of black tea flavonoid supplementation dose or duration on both SBP and DBP. Sensitivity analysis showed that no individual study had a significant impact on our results. In addition, we found no evidence for the presence of small-study effects among studies for both SBP and DBP. Thus, the favorable effect of black tea supplementation emerging from the current meta-analysis suggests the possible use of this tea as an active compound in order to promote cardiovascular health, mostly when used for longer duration (>7 days) and in men. Furthermore RCTs using different doses of black tea and various durations may contribute to confirming our conclusion.

The effect of zinc supplementation on blood pressure: a systematic review and dose-response meta-analysis of randomized-controlled trials

PURPOSE

Despite previous investigations on the effects of zinc supplementation on blood pressure, inconsistent findings are available in this regard. Therefore, we conducted a systematic review and meta-analysis of randomized clinical trials on the effects of zinc supplementation on blood pressure (BP) in adults.

METHODS

Relevant studies published up to September 2019 were searched through PubMed/Medline, Scopus, ISI Web of Science, and Google Scholar using suitable keywords. All randomized clinical trials (RCTs) that examined the effect of oral zinc supplementation on systolic blood pressure (SBP) or diastolic blood pressure (DBP) in adults were included.

RESULTS

Overall, nine trials were included in our study. Zinc supplementation significantly reduced SBP compared to the control [weighted mean differences (WMD) - 1.49 mmHg; 95% CI - 2.85 to - 0.13; P = 0.03]. However, zinc supplementation had no significant effects on DBP (WMD - 0.88 mmHg; 95% CI - 2.04 to 0.29; P = 0.14). Nonlinear analysis failed to indicate a significant influence of supplementation dosage or duration on both SBP and DBP. Sensitivity analysis showed that no individual study had a significant impact on our final results. In addition, we found no evidence for the presence of small-study effects among studies for both SBP and DBP.

CONCLUSION

We found a significant reduction in SBP following zinc supplementation. However, zinc supplementation had no significant effect on DBP. In addition, no nonlinear association was found between supplementation dosage and duration with changes in both SBP and DBP. Further RCTs using different dosages of zinc in various durations are required to confirm our conclusion.

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.