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

Protective Role of Dietary Polyphenols in the Management and Treatment of Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM), a serious metabolic disorder, is a worldwide health problem due to the alarming rise in prevalence and elevated morbidity and mortality. Chronic hyperglycemia, insulin resistance, and ineffective insulin effect and secretion are hallmarks of T2DM, leading to many serious secondary complications. These include, in particular, cardiovascular disorders, diabetic neuropathy, nephropathy and retinopathy, diabetic foot, osteoporosis, liver damage, susceptibility to infections and some cancers. Polyphenols such as flavonoids, phenolic acids, stilbenes, tannins, and lignans constitute an extensive and heterogeneous group of phytochemicals in fresh fruits, vegetables and their products. Various in vitro studies, animal model studies and available clinical trials revealed that flavonoids (e.g., quercetin, kaempferol, rutin, epicatechin, genistein, daidzein, anthocyanins), phenolic acids (e.g., chlorogenic, caffeic, ellagic, gallic acids, curcumin), stilbenes (e.g., resveratrol), tannins (e.g., procyanidin B2, seaweed phlorotannins), lignans (e.g., pinoresinol) have the ability to lower hyperglycemia, enhance insulin sensitivity and improve insulin secretion, scavenge reactive oxygen species, reduce chronic inflammation, modulate gut microbiota, and alleviate secondary complications of T2DM. The interaction between polyphenols and conventional antidiabetic drugs offers a promising strategy in the management and treatment of T2DM, especially in advanced disease stages. Synergistic effects of polyphenols with antidiabetic drugs have been documented, but also antagonistic interactions that may impair drug efficacy. Therefore, additional research is required to clarify mutual interactions in order to use the knowledge in clinical applications. Nevertheless, dietary polyphenols can be successfully applied as part of supportive treatment for T2DM, as they reduce both obvious clinical symptoms and secondary complications.

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.

Clinical Evaluation of a Novel, Patented Green Coffee Bean Extract (GCB70®), Enriched in 70% Chlorogenic Acid, in Overweight Individuals

OBJECTIVE

Obesity and overweight are challenging health problems of the millennium that lead to diabetes, hypertension, dyslipidemia, nonalcoholic fatty liver disease (NAFLD), and atherosclerosis. Green coffee bean exhibited significant promise in healthy weight management, potentiating glucose-insulin sensitization and supporting liver health. The safety and efficacy of a novel, patented water-soluble green coffee bean extract (GCB70® enriched in 70% total chlorogenic acid and <1% caffeine) was investigated in 105 participants for 12 consecutive weeks. An institutional review board and Drugs Controller General (India) (DCGI) approvals were obtained, and the study was registered at ClinicalTrials.gov.

METHOD

Body weight, body mass index (BMI), waist circumference, lipid profile, plasma leptin, glycosylated hemoglobin (HbA1c), and total blood chemistry were assessed over a period of 12 weeks of treatment. Safety was affirmed.

RESULTS

GCB70 (500 mg BID) supplementation significantly reduced body weight (approximately 6%; p = 0.000**) in approximately 97% of the study population. About a 5.65% statistically significant reduction (p = 0.000**) in BMI was observed in 96% of the study volunteers. Waist circumference was significantly reduced by 6.77% and 6.62% in 98% of the male and female participants, respectively. Plasma leptin levels decreased by 13.6% in 99% of the study population as compared to the baseline value. Upon completion of 12 weeks' treatment, fasting glucose levels decreased by 13.05% (p = 0.000**) in 79% of the study population. There was a statistically significant decrease in HbA1c levels in both male and female participants (p = 0.000**), while 86.7% of the study participants showed a statistically significant decrease in thyroid-stimulating hormone (TSH) levels (p = 0.000**). The mean decrease in TSH levels on completion of the treatment was 14.07% in the study population as compared to baseline levels. Total blood chemistry analysis exhibited broad-spectrum safety.

CONCLUSIONS

This investigation demonstrated that GCB70 is safe and efficacious in healthy weight management.

Effects of decaffeinated green coffee extract supplementation on anthropometric indices, blood glucose, leptin, adiponectin and neuropeptide Y (NPY) in breast cancer survivors: a randomized clinical trial

Objective: This study aimed to evaluate the effects of decaffeinated green coffee extract (DGCE) supplementation on anthropometric indices, blood glucose, leptin, adiponectin, and neuropeptide Y (NPY) in breast cancer survivors with obesity. Method: A total of 44 breast cancer survivors with obesity aged between 18 and 70 years and with a mean body mass index (BMI) of 31.62 ± 4.97 kg m^-2 participated in this double-blind randomized clinical trial. Eligible patients were randomized to the intervention (n = 22) and control (n = 22) groups. They received two 400 mg capsules of DGCE or two identical placebos daily for 12 weeks. Serum concentrations of leptin, adiponectin, NPY, fasting blood sugar, insulin, and homeostatic model assessment for insulin resistance (HOMA-IR) were measured at the baseline and after completion of the intervention. Also, weight, waist circumference, fat percentage, muscle percentage, and visceral fat were measured. Results: There were no significant differences in terms of changes of anthropometric indices and concentrations of leptin, adiponectin, NPY, and blood sugar between the two studied groups. Conclusion: Supplementation with DGCE in breast cancer survivors with obesity had no significant effect on anthropometric indices and blood glucose, leptin, adiponectin, and NPY levels.

Dietary Supplements for Weight Management: A Narrative Review of Safety and Metabolic Health Benefits

Dietary supplements for weight management include myriad ingredients with thermogenic, lipotropic, satiety, and other metabolic effects. Recently, the safety of this product category has been questioned. In this review, we summarize the safety evidence as well as relevant clinical findings on weight management and metabolic effects of six representative dietary supplement ingredients: caffeine, green tea extract (GTE), green coffee bean extract (GCBE), choline, glucomannan, and capsaicinoids and capsinoids. Of these, caffeine, GTE (specifically epigallocatechin gallate [EGCG]), and choline have recommended intake limits, which appear not to be exceeded when used according to manufacturers’ instructions. Serious adverse events from supplements with these ingredients are rare and typically involve unusually high intakes. As with any dietary component, the potential for gastrointestinal intolerance, as well as possible interactions with concomitant medications/supplements exist, and the health status of the consumer should be considered when consuming these components. Most of the ingredients reviewed also improved markers of metabolic health, such as glucose, lipids, and blood pressure, although the data are limited for some. In summary, weight management supplements containing caffeine, GTE, GCBE, choline, glucomannan, and capsaicinoids and capsinoids are generally safe when taken as directed and demonstrate metabolic health benefits for overweight and obese people.

Insulin-Related Liver Pathways and the Therapeutic Effects of Aerobic Training, Green Coffee, and Chlorogenic Acid Supplementation in Prediabetic Mice

Background

The liver controls blood glucose levels via regulation of anabolic (glycogen synthesis and gluconeogenesis) and catabolic (glycolysis and glycogenolysis) processes through activation of the PI3K-AKT signalling pathway. The aim of this study was to assess the effect of aerobic training, green coffee, and chlorogenic acid supplementation on glucose metabolism-regulating pathways in prediabetic mice.

Methods

C57BL/6 mice were exposed to a high-fat diet and physical activity limitation to induce a state of prediabetes. After 12 weeks, mice were fed a high-fat diet compared to the control mice. The prediabetic mice were further treated with either green coffee, chlorogenic acid, or training or combinations of the same for 10 weeks. At the end of the experimental period, metabolic data (FBG, GTT, HOMA for IR, plasma level of insulinfrom systematic, AST, and ALT assessed into blood), histopathologic, and analysis of gene and protein expressions were obtained for target tissues.

Results

Training along with green coffee and chlorogenic acid supplementation improved complications of prediabetes including weight gain and elevated fasting blood glucose and plasma insulin levels. These effects were associated with the changes in mRNA levels of genes important in hepatic glycogen synthesis (GYS2), glucogenesis (PCK and G6PC2), and glycolysis (GK, PK, and PFKL).

Conclusion

The training in conjunction with green coffee or chlorogenic acid is effective in the prevention of prediabetes in mice. As these interventions are relatively inexpensive and safe application to individuals with prediabetes appears warranted.

Phytonutrient supplements and metabolic biomarkers of cardiovascular disease: An umbrella review of meta-analyses of clinical trials

Phytonutrients exert several pharmacological effects on humans. In this study, we performed an umbrella review of the association of phytonutrient supplements (PNSs) with biomarkers of cardiovascular disease. Relevant published systematic reviews and meta-analyses of clinical trials were identified by searching PubMed, Embase, and Cochrane Library until July 4, 2020. Weighted mean differences (WMDs) and 95% confidence intervals (CIs) for summarized effects and I2 statistics of heterogeneity were extracted from individual studies or reanalyzed using a random-effects model. Of the 50 included studies, pooled effects of PNSs on blood pressure, lipid profiles, and glycemic control were reported in 16, 25, and 14 articles, respectively. The findings appeared to be highly heterogeneous among individual trials of included systematic reviews and meta-analyses. Ginger (WMD = -6.36 mmHg, 95% CI = -11.27, -1.46) and Hibiscus sabdariffa (WMD = -7.58 mmHg, 95% CI = -9.69, -5.46) were associated with lowered systolic blood pressure, whereas Aloe vera, Nigella sativa, and spirulina were associated with beneficial effects on both lipid profiles and glycemic control. In summary, this umbrella review has provided up-to-date evidence for the effect of PNSs on biomarkers related to hypertension, dyslipidemia, and diabetes. The results must be interpreted with caution due to potential heterogeneity.