Is Propolis a Potential Anti-Obesogenic Agent for Obesity?

PURPOSE OF REVIEW

Propolis is a bee product that has been used for thousands of years. The chemical composition and biological activity of propolis, which has been investigated in the twentieth century, may vary according to location. Propolis polyphenols can induce thermogenesis in brown and beige fat tissue via the uncoupled protein-1 and creatinine kinase metabolic pathways. This review provides a comprehensive investigation of the structural and biological properties of propolis and provides insights into their promising potential strategies in body weight management.

RECENT FINDINGS

By raising overall energy expenditure, it might lead to body weight management. Furthermore, the phenolic components artepillin C, quercetin, catechin, and chlorogenic acid found in its composition may have anti-obesogenic effect by stimulating the sympathetic nervous system, enhancing browning in white adipose tissue, and triggering AMP-activated protein kinase activation and mitochondrial biogenesis. Propolis, a natural product, is effective in preventing obesity which is a contemporary pandemic.

New Insights on Dietary Polyphenols for the Management of Oxidative Stress and Neuroinflammation in Diabetic Retinopathy

Diabetic retinopathy (DR) is a neurodegenerative and vascular pathology that is considered one of the leading causes of blindness worldwide, resulting from complications of advanced diabetes mellitus (DM). Current therapies consist of protocols aiming to alleviate the existing clinical signs associated with microvascular alterations limited to the advanced disease stages. In response to the low resolution and limitations of the DR treatment, there is an urgent need to develop more effective alternative therapies to optimize glycemic, vascular, and neuronal parameters, including the reduction in the cellular damage promoted by inflammation and oxidative stress. Recent evidence has shown that dietary polyphenols reduce oxidative and inflammatory parameters of various diseases by modulating multiple cell signaling pathways and gene expression, contributing to the improvement of several chronic diseases, including metabolic and neurodegenerative diseases. However, despite the growing evidence for the bioactivities of phenolic compounds, there is still a lack of data, especially from human studies, on the therapeutic potential of these substances. This review aims to comprehensively describe and clarify the effects of dietary phenolic compounds on the pathophysiological mechanisms involved in DR, especially those of oxidative and inflammatory nature, through evidence from experimental studies. Finally, the review highlights the potential of dietary phenolic compounds as a prophylactic and therapeutic strategy and the need for further clinical studies approaching the efficacy of these substances in DR management.

The association between dietary diabetic risk reduction score with anthropometric and body composition variables in overweight and obese women: a cross-sectional study

Dietary diabetes risk reduction score (DDRRs) is inversely associated with a lower risk of type 2 diabetes. Given the importance of the association between body fat and insulin resistance and the effect of diet on these parameters, this study aimed to investigate the association between DDRRS and body composition parameters, including the visceral adiposity index (VAI), lipid accumulation product (LAP), and skeletal muscle mass (SMM). This study was conducted on 291 overweight and obese women aged 18-48 years old recruited from 20 Tehran Health Centers in 2018. The anthropometric indices, biochemical parameters, and body composition were measured. A semi-quantitative food frequency questionnaire (FFQ) was used to calculate DDRRs. Linear regression analysis was used to examine the association between DDRRs and body composition indicators. The mean (SD) age of participants was 36.67 (9.10) years. After adjustment for potential confounders, VAI (β = 0.27, 95% CI = - 0.73, 1.27, Ptrend = 0.052), LAP (β = 8.14, 95% CI = - 10.54, 26.82, Ptrend = 0.069), TF (β = - 1.41, 95% CI = 11.45, 17.30, Ptrend = 0.027), trunk fat percent (TF%) (β = - 21.55, 95% CI = - 44.51, 1.61, Ptrend = 0.074), body fat mass (BFM) (β = - 3.26, 95% CI = - 6.08, - 0.44, Ptrend = 0.026), visceral fat area (VFA) (β = - 45.75, 95% CI = - 86.10, - 5.41, Ptrend = 0.026), waist-to-hip ratio (WHtR) (β = - 0.014, 95% CI = - 0.031, 0.004, Ptrend = 0.066), visceral fat level (VFL) (β = - 0.38, 95% CI = - 5.89, 5.12, Ptrend = 0.064), fat mass index (FMI) (β = - 1.15, 95% CI = - 2.28, - 0.02, Ptrend = 0.048) decreased significantly over tertiles of DDRRs, and also there was no significant association between SMM and DDRRs tertiles (β = - 0.57, 95% CI = - 1.69, 0.53, Ptrend = 0.322). The findings of this study demonstrated that participants with higher adherence to the DDRRs had lower VAI (β = 0.78 vs 0.27) and LAP (β = 20.73 vs 8.14). However, there was no significant association between DDRRs and VAI, LAP and SMM, which are mentioned as the primary outcomes. Future studies with larger sample of both genders are needed to investigate our findings.

Oxidative Stress and Cognitive Decline: The Neuroprotective Role of Natural Antioxidants

Free- radicals (Oxygen and Nitrogen species) are formed in mitochondria during the oxidative phosphorylation. Their high reactivity, due to not-engaged electrons, leads to an increase of the oxidative stress. This condition affects above all the brain, that usually needs a large oxygen amount and in which there is the major possibility to accumulate "Reacting Species." Antioxidant molecules are fundamental in limiting free-radical damage, in particular in the central nervous system: the oxidative stress, in fact, seems to worsen the course of neurodegenerative diseases. The aim of this review is to sum up natural antioxidant molecules with the greatest neuroprotective properties against free radical genesis, understanding their relationship with the Central Nervous System.

Black soybean improves the vascular function through an increase in nitric oxide and a decrease in oxidative stress in healthy women

Vascular dysfunction and injurious stimuli such as oxidative stress is closely related to the risk of cardiovascular diseases (CVD). Dietary polyphenols is reported to exert the beneficial effects on reducing the risk of CVD. Black soybean is rich in polyphenols, including isoflavones, anthocyanidins and flavan-3-ols, and its prevention effects on CVD risk were reported in the animal experiments. In this study, we investigated the effect of black soybean consumption on the vascular function and oxidative stress associating with the polyphenol concentrations in healthy women. Lowered vascular age was observed in 33 out of 44 volunteers who completed the 8-week trial. It was observed that improvement of the vascular stiffness, increasing in the urinary NO2 and NO3 level, and decreasing in the oxidative stress markers, 8-hydroxy-2'-deoxyguanosine, hexanoyl-lysine and myeloperoxidase. In addition, concentration of 12 polyphenols in black soybean increased in the plasma and urine. Increased concentration of polyphenols would be involved in the decreased oxidative stress. Thus, black soybean consumption improved the vascular function through an increase in nitric oxide and a decrease in oxidative stress accompanied by increasing the polyphenol concentrations in healthy women.

Daily Coffee and Green Tea Consumption Is Inversely Associated with Body Mass Index, Body Fat Percentage, and Cardio-Ankle Vascular Index in Middle-Aged Japanese Women: A Cross-Sectional Study

This study aimed to investigate the links between coffee (CF)/green tea (GT) consumption and body composition/cardiovascular parameters in middle-aged Japanese women. We conducted a cross-sectional study of 232 Japanese women aged 40-65 years who had been referred to the menopause clinic of Tokyo Medical and Dental University Hospital between November 2007 and August 2017. Body composition, cardiovascular parameters, and CF/GT consumption frequency were evaluated on their initial visits, using a body composition analyzer, vascular screening system, and brief-type self-administered diet history questionnaire, respectively. We investigated the associations between variables using multivariate logistic regression. After adjustment for age, menopausal status, and other factors, daily CF consumption was inversely associated with high body mass index (BMI) (adjusted odds ratio, 0.14; 95% confidence interval, 0.14-0.96) and body fat percentage (BF%) (0.33; 0.14-0.82), and daily GT consumption with high BF% (0.36; 0.14-0.96). Daily CF + GT consumption was also inversely associated with high BMI (0.15; 0.05-0.50) and BF% (0.30; 0.12-0.74). In pre- and perimenopausal women, daily CF + GT consumption was inversely associated with high cardio-ankle vascular index (CAVI) (0.05; 0.003-0.743). In conclusion, daily CF/GT consumption was inversely associated with high BMI, BF%, and CAVI in middle-aged Japanese women.

Safety Pharmacological Evaluation of the Coffee Component, Caffeoylquinic Acid, and Its Metabolites, Using Ex Vivo and In Vitro Profiling Assays

Although coffee components have gained interest for use as pharmaceuticals, little is known about their safety pharmacological effects. Hence, we aimed to evaluate the safety pharmacological effects of a chlorogenic acid (CGA)-related compound contained in coffee, 5-O-caffeoylquinic acid (5-CQA), and its metabolites, 5-O-feruloylquinic acid (5-FQA), caffeic acid (CA), and ferulic acid (FA). Langendorff perfused heart assay, electrophysiological assay of acute rat hippocampal slices, and in vitro Magnus assay of gastrointestinal tracts were conducted at 1–100 µM. Moreover, in vitro profiling assays against 38 major targets were conducted. In the Langendorff assay, no significant adverse effects were observed. In the electrophysiological assay, although epileptiform discharge rates were increased at 10 µM CA with 4-aminopyridine, and area under the curve (AUC) and number of population spike were increased at 10 µM FA with bicuculline, dose dependency was not confirmed, and no significant changes were observed at 1 µM and by CGAs alone. In the Magnus assay, a slight increase in contraction activity was observed at >1 µM FA in the stomach fundi and 100 µM 5-CQA in the ileum, suggesting enterokinesis promotion. No significant interactions were observed in the in vitro profiling assays. Therefore, CGAs could have a fundamental function as safe pharmaceuticals.

Coffee Abundant in Chlorogenic Acids Reduces Abdominal Fat in Overweight Adults: A Randomized, Double-Blind, Controlled Trial

The components of roasted or green coffee beans that promote abdominal fat reduction are not clear. We investigated the effects of daily consumption of coffee enriched in chlorogenic acids (CGA) on abdominal fat area in a randomized, double-blind, parallel controlled trial. Healthy, overweight men and women (n = 150, body mass index (BMI) ≥25 to <30 kg/m²) were randomly allocated to high-CGA (369 mg CGA/serving) or control (35 mg CGA/serving) coffee groups. Instant coffee was consumed once daily for 12 weeks, with four-week pre- and post-observation periods. Abdominal fat area and anthropometric measurements were analyzed at baseline and at four, eight, and 12 weeks, and 142 subjects completed the trial. Visceral fat area (VFA), total abdominal fat area (TFA), body weight, and waist circumference significantly decreased in the CGA group compared with the control group, with a group × time interaction (p < 0.001, p = 0.001, p = 0.025, and p = 0.001, respectively). Changes in VFA and TFA from baseline to 12 weeks were significantly greater in the CGA group than in the control group (−9.0 ± 13.9 cm² vs. −1.0 ± 14.3 cm², p < 0.001; −13.8 ± 22.9 cm² vs. −2.0 ± 16.2 cm², p < 0.001). No severe adverse events occurred. Consumption of high-CGA coffee for 12 weeks by overweight adults might lower VFA, TFA, BMI, and waist circumference.

Miso (Fermented Soybean Paste) Suppresses Visceral Fat Accumulation in Mice, Especially in Combination with Exercise

We investigated whether the difference in miso consumption between the Japanese diets of 1975 and 2010 has influenced the observed increase in diet-induced obesity. To recreate the 2010 and 1975 Japanese high-fat diets with the corresponding proportions of miso, freeze-dried miso was added to high-fat mouse feed at 1.6% and 2.6%, respectively. When 5-week-old male Institute of Cancer Research (ICR) mice were provided each of these diets ad libitum for 8 weeks, it was found that the white adipose tissue weight and adipocyte area were lower in mice receiving the 1975 diet than in those receiving the 2010 diet. Therefore, high miso consumption is one reason why the 1975 Japanese diet tended to not lead to obesity. Next, the combined effects of treadmill exercise and miso consumption were investigated. The mice were divided into three groups, which were provided either a high-fat diet (group C), a high-fat diet with exercise (group C + E), or a miso-supplemented high-fat diet with exercise (group M + E) for 8 weeks. In this experiment, the white adipose tissue weight and adipocyte area in group M + E were lower than in group C. When the mRNA expression of lipid metabolism-associated genes in adipose tissue was measured, we found that expression of Hsl (lipase, hormone sensitive), which is involved in lipolysis, and Pparγ (peroxisome proliferator activated receptor gamma), which regulates adipocyte differentiation upstream of Hsl, was increased in group M + E. These results clearly demonstrated that lipid accumulation in the adipose tissues is suppressed by miso consumption in combination with exercise.

Ingestion of coffee polyphenols suppresses deterioration of skin barrier function after barrier disruption, concomitant with the modulation of autonomic nervous system activity in healthy subjects

The aim of this study was to evaluate the effect of consumption of coffee polyphenols (CPPs) on the autonomic nervous system activity and decreased skin barrier function caused by sodium dodecyl sulfate (SDS) treatment. In this single-blind, placebo-controlled study, ten healthy male subjects consumed either a beverage containing CPPs or a placebo beverage for four weeks. CPPs significantly suppressed the deterioration in skin barrier function and skin moisture content induced by SDS treatment after the third week. Furthermore, in the heart rate variability analysis, CPPs significantly produced an increase in parasympathetic nervous activity, and a decrease in sympathetic nervous activity after the four weeks of beverage consumption. These results suggest that CPPs might influence the regulation of the autonomic nervous system and contribute to the suppressive effect on deterioration of skin barrier function.

Effects of Chlorogenic Acid-Enriched and Hydroxyhydroquinone-Reduced Coffee on Postprandial Fat Oxidation and Antioxidative Capacity in Healthy Men: A Randomized, Double-Blind, Placebo-Controlled, Crossover Trial

Chlorogenic acids (CGAs) reduce blood pressure and body fat, and enhance fat metabolism. In roasted coffee, CGAs exist together with the oxidant component hydroxyhydroquinone (HHQ). HHQ counteracts the antihypertensive effects of CGA, but its effects on CGA-induced fat oxidation (FOX) are unknown. Here we assessed the effects of CGA-enriched and HHQ-reduced coffee on FOX. Fifteen healthy male volunteers (age: 38 ± 8 years (mean ± SD); BMI: 22.4 ± 1.5 kg/m²) participated in this crossover study. Subjects consumed the test beverage (coffee) containing the same amount of CGA with HHQ (CGA-HHQ(+)) or without HHQ (CGA-HHQ(−)) for four weeks. Postprandial FOX and the ratio of the biological antioxidant potential (BAP) to the derivatives of reactive oxygen metabolites (d-ROMs) as an indicator of oxidative stress were assessed. After the four-week intervention, postprandial FOX and the postprandial BAP/d-ROMs ratio were significantly higher in the CGA-HHQ(−) group compared with the CGA-HHQ(+) group (4 ± 23 mg/min, group effect: p = 0.040; 0.27 ± 0.74, group effect: p = 0.007, respectively). In conclusion, reducing the amount of HHQ facilitated the postprandial FOX effects of CGA in coffee. Our findings also suggest that the mechanism underlying the inhibition of FOX by HHQ is related to postprandial oxidative stress.

Effect of Chlorogenic Acid Intake on Cognitive Function in the Elderly: A Pilot Study

Objective

To evaluate the effect of chlorogenic acids (CGAs) intake on cognitive function.

Methods

In this pilot study, the Cogstate and CNS Vital Signs test batteries were used to evaluate cognitive function in 8 healthy elderly men and women complaining of subjective memory loss after a 6-month intake of a test beverage containing 330 mg of CGAs just before bedtime.

Results

After a 6-month CGA intake period, significant improvement was observed in the One Back Test of the Cogstate, the Shifting Attention Test, and Finger Tapping Test as well as in the composite memory, verbal memory, complex attention, cognitive flexibility, executive function, and motor speed domains of the CNS Vital Signs test battery.

Conclusion

A 6-month intake of CGAs may improve attentional, executive, and memory functions in the elderly with complaints of subjective memory loss.

Effects of subacute ingestion of chlorogenic acids on sleep architecture and energy metabolism through activity of the autonomic nervous system: a randomised, placebo-controlled, double-blinded cross-over trial

Chlorogenic acids (CGA) are the most abundant polyphenols in coffee. Continuous consumption of CGA reduces body fat and body weight. Since energy metabolism and sleep are controlled by common regulatory factors, consumption of CGA might modulate sleep. Lack of sleep has been identified as a risk factor for obesity, hypertension and type 2 diabetes. The aim of this study was to determine the effects of ingesting CGA over 5 d on energy metabolism and sleep quality in humans. A total of nine healthy subjects (four male and five female) completed a placebo-controlled, double-blinded, cross-over intervention study. Subjects consumed a test beverage containing 0 or 600 mg of CGA for 5 d. On the fifth night, subjects stayed in a whole-room metabolic chamber to measure energy metabolism; sleep was evaluated using polysomnographic recording. It was found that CGA shortened sleep latency (9 (sem 2) v. 16 (sem 4) min, P<0·05) compared with the control, whereas no effect on sleep architecture, such as slow-wave sleep, rapid eye movement or waking after sleep onset, was observed. Indirect calorimetry revealed that consumption of CGA increased fat oxidation (510 (sem 84) kJ/8 h (122 (sem 20) kcal/8 h) v. 331 (sem 79) kJ/8 h (81 (sem 19) kcal/8 h), P<0·05) but did not affect energy expenditure during sleep. Consumption of CGA enhanced parasympathetic activity assessed from heart-rate variability during sleep (999 (sem 77) v. 919 (sem 54), P<0·05). A period of 5-d CGA consumption significantly increased fat oxidation during sleep, suggesting that beverages containing CGA may be beneficial to reduce body fat and prevent obesity. Consumption of CGA shortened sleep latency and did not adversely affect sleep quality.

Reduction in hydroxyhydroquinone from coffee increases postprandial fat utilization in healthy humans: a randomized double-blind, cross-over trial

The present study aimed to clarify the effect of reduction in hydroxyhydroquinone (HHQ) from roasted coffee on energy utilization in humans. Indirect calorimetry showed that one-week ingestion of HHQ-reduced coffee led to significantly higher postprandial fat utilization than that of HHQ-containing coffee. This finding indicates that reduction in HHQ from coffee increases postprandial fat utilization.

Antioxidative and Antidiabetic Effects of Natural Polyphenols and Isoflavones

Many polyphenols that contain more than two phenolic hydroxyl groups are natural antioxidants and can provide health benefits to humans. These polyphenols include, for example, oleuropein, hydroxytyrosol, catechin, chlorogenic acids, hesperidin, nobiletin, and isoflavones. These have been studied widely because of their strong radical-scavenging and antioxidative effects. These effects may contribute to the prevention of diseases, such as diabetes. Insulin secretion, insulin resistance, and homeostasis are important factors in the onset of diabetes, a disease that is associated with dysfunction of pancreatic β-cells. Oxidative stress is thought to contribute to this dysfunction and the effects of antioxidants on the pathogenesis of diabetes have, therefore, been investigated. Here, we summarize the antioxidative effects of polyphenols from the perspective of their radical-scavenging activities as well as their effects on signal transduction pathways. We also describe the preventative effects of polyphenols on diabetes by referring to recent studies including those reported by us. Appropriate analytical approaches for evaluating antioxidants in studies on the prevention of diabetes are comprehensively reviewed.

Coffee polyphenol consumption improves postprandial hyperglycemia associated with impaired vascular endothelial function in healthy male adults

Epidemiological studies indicate that habitual coffee consumption lowers the risk of diabetes and cardiovascular diseases. Postprandial hyperglycemia is a direct and independent risk factor for cardiovascular diseases. We previously demonstrated that coffee polyphenol ingestion increased secretion of Glucagon-like peptide 1 (GLP-1), which has been shown to exhibit anti-diabetic and cardiovascular effects. We hypothesized coffee polyphenol consumption may improve postprandial hyperglycemia and vascular endothelial function by increasing GLP-1 release and/or reducing oxidative stress. To examine this hypothesis, we conducted a randomized, acute, crossover, intervention study in healthy male adults, measuring blood parameters and flow-mediated dilation (FMD) after ingestion of a meal with or without coffee polyphenol extract (CPE). Nineteen subjects consumed a test meal with either a placebo- or CPE-containing beverage. Blood biomarkers and FMD were measured at fasting and up to 180 minutes postprandially. The CPE beverage led to a significantly lower peak postprandial increase in blood glucose and diacron-reactive oxygen metabolite, and significantly higher postprandial FMD than the placebo beverage. Postprandial blood GLP-1 increase tended to be higher after ingestion of the CPE beverage, compared with placebo. Subclass analysis revealed that the CPE beverage significantly improved postprandial blood GLP-1 response and reduced blood glucose increase in the subjects with a lower insulinogenic index. Correlation analysis showed postprandial FMD was negatively associated with blood glucose increase after ingestion of the CPE beverage. In conclusion, these results suggest that coffee polyphenol consumption improves postprandial hyperglycemia and vascular endothelial function, which is associated with increased GLP-1 secretion and decreased oxidative stress in healthy humans.

Ingestion of coffee polyphenols increases postprandial release of the active glucagon-like peptide-1 (GLP-1(7-36)) amide in C57BL/6J mice

The widespread prevalence of diabetes, caused by impaired insulin secretion and insulin resistance, is now a worldwide health problem. Glucagon-like peptide 1 (GLP-1) is a major intestinal hormone that stimulates glucose-induced insulin secretion from β cells. Prolonged activation of the GLP-1 signal has been shown to attenuate diabetes in animals and human subjects. Therefore, GLP-1 secretagogues are attractive targets for the treatment of diabetes. Recent epidemiological studies have reported that an increase in daily coffee consumption lowers diabetes risk. The present study examined the hypothesis that the reduction in diabetes risk associated with coffee consumption may be mediated by the stimulation of GLP-1 release by coffee polyphenol extract (CPE). GLP-1 secretion by human enteroendocrine NCI-H716 cells was augmented in a dose-dependent manner by the addition of CPE, and was compatible with the increase in observed active GLP-1(7-36) amide levels in the portal blood after administration with CPE alone in mice. CPE increased intracellular cyclic AMP (cAMP) levels in a dose-dependent manner, but this was not mediated by G protein-coupled receptor 119 (GPR119). The oral administration of CPE increased diet (starch and glyceryl trioleate)-induced active GLP-1 secretion and decreased glucose-dependent insulinotropic polypeptide release. Although CPE administration did not affect diet-induced insulin secretion, it decreased postprandial hyperglycaemia, which indicates that higher GLP-1 levels after the ingestion of CPE may improve insulin sensitivity. We conclude that dietary coffee polyphenols augment gut-derived active GLP-1 secretion via the cAMP-dependent pathway, which may contribute to the reduced risk of type 2 diabetes associated with daily coffee consumption.