The efficacy of propolis on markers of glycemic control in adults with type 2 diabetes mellitus: A systematic review and meta‐analysis

Effects of Propolis Consumption on Glycemic Indices and Liver Enzymes in Adults: A Grading of Recommendations Assessment, Development, and Valuation-assessed Systematic Review and Dose-Response Meta-analysis

PURPOSE

Even though various randomized controlled trials (RCTs) have assessed the effect of propolis on glycemic indices and liver enzyme concentrations in adults, results have been inconsistent, without conclusive evidence. This systematic review and meta-analysis of RCTs sought to evaluate the effects of propolis consumption on glycemic indices and liver enzymes, fasting blood glucose, insulin, homeostatic model assessment of insulin resistance, glycosylated hemoglobin, alanine transaminase, aspartate aminotransferase, and gamma-glutamyl transferase in adults.

METHODS

Two independent researchers systematically searched PubMed, EMBASE, Scopus, Web of Science, and the Cochrane Library for English-language RCTs published up to April 2024. The results were generated through a random-effects model and presented as the weighted mean difference (WMD) with a 95% CI. The Cochrane Risk of Bias Tool for RCTs and Grading of Recommendations Assessment, Development, and Evaluation assessment were used to evaluate quality assessment and certainty of evidence.

FINDINGS

A total of 21 RCTs were included. A pooled analysis of 24 trials reported that propolis consumption led to a significant reduction in fasting blood glucose (WMD, -9.75 mg/dL; 95% CI, -16.14 to -3.35), insulin (WMD, -1.64 µU/mL; 95% CI, -2.61 to -0.68), glycosylated hemoglobin (WMD, -0.46%; 95% CI, -0.71 to -0.21), homeostatic model assessment of insulin resistance (WMD, -0.54; 95% CI, -0.98 to -0.09), alanine transaminase (WMD, -2.60 IU/L; 95% CI, -4.58 to -0.61), and aspartate aminotransferase (WMD, -2.07 IU/L; 95% CI, -3.05 to -1.09). However, there were no significant effects on gamma-glutamyl transferase in comparison with the control group.

IMPLICATIONS

This meta-analysis has shown that propolis supplementation may have beneficial effects on glycemic indices and liver enzymes. Future high-quality, long-term RCTs are needed to confirm our results.

CLINICALTRIALS

gov identifiers: CRD42024524763. (Clin Ther. 2024;46:XXX-XXX) © 2024 Elsevier HS Journals, Inc.

The effects of MIND diet and propolis supplementation on metabolic syndrome: A randomized controlled clinical trial

The MIND is a novel eating plan preserves cognitive function. Propolis is a resinous substance that has several biological and medicinal properties. This study examines the effect of the MIND diet and propolis supplementation on MetS indices among metabolic syndrome subjects. This RCT study, was conducted on adults with metabolic syndrome who were referred to the Hazrat Ali Health Center in Isfahan. 84 eligible subjects were divided into 3 groups. Including MIND diet + Propolis supplement, MIND diet + placebo, and control group. The data obtained from the subjects was analyzed in two descriptive and analytic levels. The Shapiro-Wilk test and examination of skewness were conducted to assess the normality of the distribution of quantitative variables. Quantitative variables were reported using either the mean (SD). SPSS Statistics software version 26 was used for statistical analysis of data. In this study the MIND + Propolis group compared to the control group after adjusting variables showed a significant decrease (p-value < 0.05) in weight, BMI, WC, SBP, DBP, and TG by 0.97 times (3%), 0.97 times (3%), 0.98 times (2%), 0.93 times (7%), 0.94 times (6%), and 0.75 times (25%), respectively; this significant change was also observed in FBS (p-value < 0.001) by 0.85 times (15%), and HDL-C (mg/dl) has shown a significant increase (p-value < 0.05) by 1.17 times (17%). MIND group compared to the control group after adjusting variables showed a significant decrease (p-value < 0.05) in BMI, WC, and SBP by 0.98 times (2%), 0.98 times (2%), and 0.95 times (5%), respectively; this significant change (p-value < 0.001) was also observed in DBP, FBS, and TG by 0.92 times (8%), 0.83 times (17%), and 0.71 times (29%), respectively; HDL-C has shown a significant increase (p-value < 0.001) by 1.21 times (21%), and weight has shown a non-significant decrease (p-value = 0.055) by 0.98 times (2%). This study indicated that the MIND diet + Propolis supplement and MIND diet compared to the control group can significantly decrease BMI, WC, SBP, DBP, FBS, TG, and weight (non-significant for the MIND group), and also increase HDL-C.

Effects of MIND diet and propolis supplementation on metabolic syndrome indices and cognitive function among patients with metabolic syndrome in Isfahan, Iran, 2024. A rationale and study protocol for randomized controlled trial

Metabolic syndrome (MetS) is the main general and clinical health challenge worldwide. Based on the National Cholesterol Education Program, if the person has three or more indices containing: elevated fasting blood sugar, high levels of triglycerides, hypertension, low levels of high-density lipoprotein cholesterol, and central obesity, he suffers MetS. The Mediterranean-Dietary Approaches to Stop Hypertension (DASH) Intervention for Neurodegenerative Delay diet is a novel diet that with the specific aim of safeguarding cognitive function. Propolis is a resinous substance produced by bees from the combination of buds and secretions of plants with saliva and bee enzymes. After propolis supplementation, a significant reduction in fasting plasma glucose levels and lipid profiles has been observed. Considering the importance of chronic diseases like MetS on health, the role of the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet and propolis supplement that will improve blood sugar, blood lipid, anthropometric indicators, blood pressure, and cognitive function, and limited contradictory studies, we decided to conduct this study. This study, which is a randomized controlled clinical trial study, will be conducted on adults with MetS who will visit Hazrat Ali Health Center in Isfahan. Participants must provide informed consent before engaging in the study. Demographic data such as age, gender, and medical history will be recorded. Then, anthropometric indices, MetS indices, and cognitive function will be measured in all subjects. The study participants will be divided into three groups and will be controlled for 12 weeks. We will have a MIND diet + placebo group, a MIND diet + propolis supplement group, and a control group that will receive a microcrystalline cellulose placebo and usual dietary advice. At the end of the intervention, all indices will be assessed again. The data obtained in the study will be analyzed at descriptive and analytical levels by the statistical software SPSS26. The present study's protocol was approved by the Iranian Registry of Clinical Trials (www.irct.ir) on 3/28/2023 and a registration reference is IRCT20230105057054N1.

Effects of dried okra extract on lipid profile, renal function and some RAGE-related inflammatory genes expression in patients with diabetic nephropathy: A randomized controlled trial

BACKGROUND

Diabetic nephropathy (DN) is a common complication of type 2 diabetes. Okra (Abelmoschus esculentus L) is reported to have anti-diabetic effects. The present study aimed to investigate the effects of dried okra extract (DOE) supplementation on lipid profile, renal function indices, and expression of inflammatory genes, as well as serum level of soluble Receptor for Advanced glycation end products (sRAGE) in patients with DN.

METHODS

In this triple-blind randomized placebo-controlled clinical trial, 64 eligible patients with DN received either 125 mg of DOE or placebo daily along with DN-related nutritional recommendations for 10 weeks. Changes in kidney indices including proteinuria and estimated glomerular filtration rate (eGFR), lipid profile, serum SRAGE, as well as the expression of RAGE, ICAM-1, and IL-1 genes were measured over 10 weeks.

RESULTS

After adjustment for the potential confounders, between-group analyses showed no significant differences in terms of lipid profile, kidney function indices, sRAGE, and RAGE-related inflammatory genes expression after 10 weeks.

CONCLUSION

Daily 125 mg DOE along with nutritional recommendations on top of usual care did not lead to significant changes in renal function indices, lipid profile, and inflammatory genes expression in patients with DN.

Propolis as an adjunctive therapy for treatment of uncomplicated cystitis in women: A randomized double-blind placebo-controlled trial

The current research is designed to investigate the effect of propolis supplementation on the clinical manifestations in women suffering from uncomplicated cystitis. In this randomized double-blind, placebo-controlled trial, 120 women with uncomplicated cystitis were selected and randomly assigned into two groups to receive two 500 mg capsules of propolis or placebo daily for 7 days along with ciprofloxacin (250 mg). Clinical symptoms including hematuria, urinary frequency, dysuria, suprapubic pain, and urgency, as well as bacteriuria, were assessed before and after the intervention. After supplementation, participants in the intervention group had significantly fewer days of urinary frequency (p < 0.001), dysuria (p = 0.005), and urgency (p = 0.03). However, there was no significant difference between the two groups regarding hematuria and suprapubic pain (p > 0.05). Furthermore, the severity of bacteriuria decreased significantly in both groups. In conclusion, it seems that propolis supplementation in women with uncomplicated cystitis could improve urinary frequency, dysuria, and urgency. However, further clinical trials should be conducted to fully understand the effects of propolis in women suffering from uncomplicated cystitis.

A Propolis-Derived Small Molecule Tectochrysin Ameliorates Type 2 Diabetes in Mice by Activating Insulin Receptor β

SCOPE

Propolis has been found to decrease glucose levels and increase insulin sensitivity in type 2 diabetes. However, the active ingredient responsible for these effects and its regulating mechanism are not fully understood.

METHODS AND RESULTS

To address this, molecular docking screening is used to screen the effective hypoglycemic ingredient in propolis and found that tectochrysin (TEC) has a high affinity to the insulin receptor (IR), highlighting its potential for glycemic control. In vivo tests show that TEC decreases glucose levels and enhances insulin sensitivity in db/db mice. By hyperinsulinemic euglycemic clamp test, this study further finds that TEC promotes glucose uptake in adipose tissue and skeletal muscle, as well as inhibits hepatic gluconeogenesis. Moreover, it finds that TEC promotes glucose uptake and adipocytes differentiation in 3T3-L1 cells like insulin, suggesting that TEC exerts an insulin mimetic effect. Mechanistically, pharmacology inhibition of IRβ abolishes the effects of TEC on glucose uptake and the phosphorylation of IR. The study further demonstrates that TEC binds to and activates IRβ by targeting its E1077 and M1079.

CONCLUSION

Therefore, this study sheds light on the mechanism underlying propolis' potential for ameliorating type 2 diabetes, offering a natural food-derived compound as a promising therapeutic option.

Anti-hyperglycemic effects of propolis or metformin in type 2 diabetes mellitus

Background: The aim of this study was to evaluate the effect of propolis or metformin versus placebo on glycemic control in pharmacological treatment-naïve patients with type 2 diabetes mellitus (T2DM). Methods: A double-blind, randomized, placebo-controlled in parallel groups clinical trial was performed in 36 pharmacological treatment-naïve patients with T2DM. They received propolis (300 mg), metformin (850 mg), or placebo twice daily before breakfast and dinner for 12 weeks. At the beginning and end of the study, fasting plasma glucose (FPG), 2-h postload glucose (2-h PG) during a 75-g oral glucose tolerance test, glycated hemoglobin A1c (A1C) and a metabolic profile were measured. Areas under the curve (AUC) of glucose and insulin, total insulin secretion (insulinogenic index), the first phase of insulin secretion (Stumvoll index), and insulin sensitivity (Matsuda index) were calculated. Statistical analyses: Kruskal-Wallis, Mann-Whitney U and Wilcoxon tests. Results: The propolis and metformin groups exhibited significant reductions in FPG (p=0.009 and p=0.001, respectively), 2-h PG (p=0.034 and p=0.001, respectively) levels, AUC of insulin, Stumvoll index, and an increment in the Matsuda index. The comparison of the changes from baseline to the end showed significant differences between placebo and propolis in FPG (p=0.004) and A1C (p=0.049) levels, while between placebo and metformin were in FPG (p=0.002), 2-h PG (p=0.004) and A1C (p=0.007) levels. Conclusions: The administration of propolis and metformin compared to placebo reduced FPG and A1C levels; in addition, metformin decreased 2-h PG, AUC of glucose and insulin, high-density lipoprotein cholesterol, and increased the insulin sensitivity.

The effect of propolis supplementation in improving antioxidant status: A systematic review and meta-analysis of controlled clinical trials

The present study aimed to assess the effect of propolis supplementation on oxidative status, a key contributor to the etiology of many chronic diseases. A systematic search of multiple databases, including Web of Science, SCOPUS, Embase, PubMed, and Google Scholar, was conducted from inception to October 2022 to identify articles examining the effect of propolis on glutathione (GSH), glutathione peroxidase (GPX), total antioxidant capacity (TAC), superoxide dismutase (SOD), and malondialdehyde (MDA) levels. The quality of the included studies was evaluated using the Cochrane Collaboration tool. A total of nine studies were included in the final analysis, and a random-effects model was used to pool the estimated effects. Results showed that propolis supplementation significantly increased the levels of GSH (SMD = 3.16; 95% CI: 1.15, 5.18; I2  = 97.2%), GPX (SMD = 0.56; 95% CI: 0.07, 1.05; p = 0.025; I2  = 62.3%), and TAC (SMD = 3.26; 95% CI: 0.89, 5.62; I2  = 97.8%, p < 0.001). However, the effect of propolis on SOD was not significant (SMD = 0.05; 95% CI: -0.25, 0.34; I2  = 0.0%). Although the MDA concentration was not significantly decreased overall (SMD = -0.85, 95% CI: -1.70, 0.09; I2  = 93.3%), a significant decrease in MDA levels was observed at doses ≥1000 mg/day (SMD = -1.90; 95% CI: -2.97, -0.82; I2  = 86.4) and supplementation durations of less than 11 weeks (SMD = -1.56; 95% CI: -2.60, -0.51; I2  = 90.4). These results suggest that propolis is a safe supplement with a beneficial effect on GSH, GPX, and TAC levels and may be an effective adjunctive therapy for diseases where oxidative stress is a key factor in the etiology. However, further high-quality studies are necessary to make more precise and comprehensive recommendations given the limited number of studies, clinical diversity, and other limitations.

Poplar Propolis Improves Insulin Homeostasis in Non-Diabetic Insulin-Resistant Volunteers with Obesity: A Crossover Randomized Controlled Trial

Propolis, a natural resinous mixture rich in polyphenols, produced by bees from a variety of plant sources, has shown significant therapeutic effects and may prevent the development of certain chronic diseases like type 2 diabetes mellitus (T2DM). The objective of this study was to evaluate the effect of supplementation with standardized poplar propolis extract powder (PPEP) on insulin homeostasis in non-diabetic insulin-resistant volunteers with obesity. In this randomized, controlled, crossover trial, nine non-diabetic insulin-resistant volunteers with obesity, aged 49 ± 7 years, were subjected to two periods of supplementation (placebo and PPEP) for 3 months. Blood samples and anthropomorphic data were collected at baseline and at the end of each phase of the intervention. PPEP supplementation improved insulin sensitivity by significantly decreasing the percentage of insulin-resistant subjects and the insulin sensitivity Matsuda index (ISI-M). According to this study, supplementation with standardized PPEP for 3 months in non-diabetic insulin-resistant volunteers with obesity led to an improvement in insulin homeostasis by its effect on insulin resistance and secretion. This study suggests that poplar propolis has a preventive effect on the physiopathological mechanisms of T2DM and, therefore, that it can help to prevent the development of the disease.

Ethanol extract of propolis regulates type 2 diabetes in mice via metabolism and gut microbiota

ETHNOPHARMACOLOGICAL RELEVANCE

Propolis is a traditional natural medicine with various activities such as antioxidant and anti-inflammatory, immunomodulatory, anti-tumour, gastroenteritis treatment and prevention, anti-microbial and parasitic, as well as glucose regulation and anti-diabetes, and is expected to be an anti-diabetic candidate with few side effects, but the mechanism of action of propolis on type 2 diabetes mellitus (T2DM) has not been fully elucidated.

AIM OF THE STUDY

The purpose of this study was to investigate the mechanism of the effect of ethanol extract of propolis (EEP) on the regulation of blood glucose in T2DM mice.

MATERIALS AND METHODS

We studied the possible mechanism of EEP on T2DM using an animal model of T2DM induced by a combination of a high-fat diet and intraperitoneal injection of streptozotocin (STZ). The experiment was divided into four groups, namely, the normal group (HC), model group (T2DM), EEP and metformin group (MET). Biochemical indexes and cytokines were measured, and the differences of metabolites in the serum were compared by ¹H-NMR. In addition, the diversity of intestinal flora in feces was studied by 16S rDNA amplicon sequencing.

RESULTS

The results showed that following treatment with EEP and MET, the weight-loss trend of mice was alleviated, and the fasting blood glucose, insulin secretion level, insulin resistance index, C peptide level and oral glucose tolerance level decreased, whereas the insulin sensitivity index increased, thereby EEP effectively alleviated the occurrence of T2DM and insulin resistance. Compared with the T2DM group, the concentrations of pro-inflammatory cytokines interleukin-1 beta (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) decreased significantly in EEP and MET groups, whereas the concentrations of anti-inflammatory cytokine interleukin-10 (IL-10) increased significantly. Metabolomics results revealed that EEP and MET regulate carbohydrate metabolism and restore amino acid and lipid metabolism. Correlation analysis of intestinal flora in mouse feces showed that compared with the HC group, harmful bacteria such as Bilophila, Eubacterium_ventriosum_group, Mucispirillum and Desulfovibrio were found in the T2DM group, whereas the abundance of beneficial bacteria such as Lactobacillus was significantly reduced. Parabacteroides, Akkermansia, Leuconostoc, and Alloprevotella were abundantly present in the EEP group; however, the MET group showed an increase in the genus Parasutterella, which could regulate energy metabolism and insulin sensitivity.

CONCLUSIONS

The results showed that EEP and MET reduce fasting blood glucose in T2DM mice, followed by alleviating insulin resistance, improving the inflammatory reaction of mice, regulating the metabolism of mice, and affecting the steady state of gut microbiota. However, the overall therapeutic effect of EEP is better than that of MET.

The effects of propolis on pro-oxidant-antioxidant balance, glycemic control, and quality of life in chronic kidney disease: a randomized, double-blind, placebo-controlled trial

Chronic kidney disease (CKD) is a progressive kidney damage with an increasing prevalence. Some evidence suggests that propolis as a novel antioxidant, anti-inflammatory, and immunomodulatory agent may have beneficial effects in CKD. The aim of this study was to evaluate the efficacy of propolis on some kidney function parameters, pro-oxidant-antioxidant balance (PAB), glycemic status, quality of life, and blood pressure (BP) in patients with CKD. In this study, 44 patients with CKD were randomly assigned to receive propolis capsules at a dose of 250 mg daily or placebo for three months. Of 44 randomized individuals, 35 completed the trial. At the end of the intervention (end of month three), improvement in some dimensions of health-related quality of life (HRQoL) (derived from Kidney Disease and Quality of Life Short-Form (KDQOL-[Formula: see text], v. 1.3) questionnaire) were significantly higher in the propolis group than the placebo group, even after adjustment for baseline values, present of diabetes, and age (P < 0.05). Like systolic and diastolic BP, changes in serum creatinine, 24-h urine volume and protein, fasting blood sugar (FBS), hemoglobin A1C (HbA1C), insulin, homeostasis model of assessment-insulin resistance (HOMA-IR), quantitative insulin sensitivity check index (QUICKI), and PAB did not differ significantly between the two groups (P > 0.05). No serious adverse events were reported throughout the study. Propolis supplementation may improve the HRQoL of CKD patients. More studies are needed to validate the adjunct use of propolis for metabolic control of CKD patients.

Effect of propolis on mood, quality of life, and metabolic profiles in subjects with metabolic syndrome: a randomized clinical trial

Metabolic syndrome (MeS) is a common multifaceted disorder. Plants contain antioxidant bioactive compounds, which are beneficial to improve the health condition of patients with MeS. Propolis is a hive natural product that is composed of various constituent. We aimed to assess the effects of Iranian propolis as a natural and safe agent on indicators of MeS, quality of life and mood status in individuals with MeS. In total, 66 interested eligible patients recruited to the present study. Participants were randomly assigned to consume a tablet at dose of 250 mg of propolis extract, twice daily for 12 weeks or placebo. Propolis supplementation could lead to a significant reduction in waist circumference (WC), increase in physical functioning, general health and the overall score of SF-36 compared with placebo group (P-value < 0.05). However, no significant differences were observed regarding other anthropometric indices and biochemical parameters between two groups (P-value > 0.05). The current study indicated that propolis can be effective in decreasing WC and improving physical health and quality of life, while had no significant effects on other components of MeS among subjects with this syndrome. Clinical trials registration Iran Registry of Clinical Trials.ir IRCT20121216011763N49, registration date 23/12/2020.

The efficacy of Da Chaihu decoction combined with metformin tablets for type 2 diabetes mellitus: A systematic review and meta-analysis

OBJECTIVE

To assess the efficacy of Da Chaihu decoction combined with metformin tablets on patients with type 2 diabetes compared with metformin alone.

METHODS

This systematic review and meta-analysis is written based on 2020 PRISMA Extension for Chinese Herbal Medicines 2020 (PRISMA-CHM 2020) reporting guidelines. We reviewed all the relevant studies from a search of the following databases from inception to February 2022 without any language restriction: Excerpta Medica Database (EMBASE), Google Scholar, PubMed, Cochrane Library, China National Knowledge Infrastructure (CNKI), VIP Information, Wanfang Data, and the Chinese Biomedical Literature Database(CBM). Data were extracted and the quality was independently evaluated by two reviewers, based on the inclusion and exclusion criteria. Data were analyzed using the Cochrane software RevMan 5.3.

RESULTS

Six randomized controlled trials comprising 516 participants were included. The meta-analysis revealed the Da Chaihu decoction combined with metformin tablets group was significantly superior to the metformin tablets group in terms of fasting blood glucose(FPG) (-0.66 mmol/L; 95 % CI (confidence intervals) [- 1.28, - 0.04]), plasma glucose 2 h after meal (2-h PG) (-1.18 mmol/L; 95 % CI [-1.94, -0.42]) in six RCTs, body mass index (BMI) (-3.07 mmol/L; 95 % CI [-6.89, 0.75]) in three RCTs, glycosylated hemoglobin (HbAlc) (-0.36 mmol/L; 95 % CI [-1.04, 0.31]) in three RCTs, and triglycerides (TG) (-0.76 mmol/L; 95 % CI [-1.37, -0.15]) in two RCTs. In two RCTs, there were significant differences in terms of total cholesterol (TC) (-0.97 mmol/L; 95 % CI [-1.18, -0.76]).

CONCLUSIONS

Very low-quality research shows that Da Chaihu decoction combined with metformin tablets exert a certain level of efficacy on patients with type 2 diabetes compared with metformin alone. However, random sequence generation methodology was reported in five studies leading to the low quality of the included studies. None of the six studies depicted the blinding method, allocation concealment, selective reporting, and assessed the purity and potency of the product. This observation requires verification through high-quality, multi-center, double-blinded randomized controlled trials, and assesses the purity and potency of the product.

Computational Study of Asian Propolis Compounds as Potential Anti-Type 2 Diabetes Mellitus Agents by Using Inverse Virtual Screening with the DIA-DB Web Server, Tanimoto Similarity Analysis, and Molecular Dynamic Simulation

Propolis contains a wide range of pharmacological activities because of their various bioactive compounds. The beneficial effect of propolis is interesting for treating type-2 diabetes mellitus (T2DM) owing to dysregulation of multiple metabolic processes. In this study, 275 of 658 Asian propolis compounds were evaluated as potential anti-T2DM agents using the DIA-DB web server towards 18 known anti-diabetes protein targets. More than 20% of all compounds could bind to more than five diabetes targets with high binding affinity (<−9.0 kcal/mol). Filtering with physicochemical and pharmacokinetic properties, including ADMET parameters, 12 compounds were identified as potential anti-T2DM with favorable ADMET properties. Six of those compounds, (2R)-7,4′-dihydroxy-5-methoxy-8-methylflavone; (RR)-(+)-3′-senecioylkhellactone; 2′,4′,6′-trihydroxy chalcone; alpinetin; pinobanksin-3-O-butyrate; and pinocembrin-5-methyl ether were first reported as anti-T2DM agents. We identified the significant T2DM targets of Asian propolis, namely retinol-binding protein-4 (RBP4) and aldose reductase (AKR1B1) that have important roles in insulin sensitivity and diabetes complication, respectively. Molecular dynamic simulations showed stable interaction of selected propolis compounds in the active site of RBP4 and AKR1B1. These findings suggest that Asian propolis compound may be effective for treatment of T2DM by targeting RBP4 and AKR1B1.

Efficacy of Antioxidant Supplementation to Non-Surgical Periodontal Therapy on Metabolic Control in Type 2 Diabetes Patients: A Network Meta-Analysis

This network meta-analysis (NMA) investigated the effectiveness of antioxidants as adjuncts to non-surgical periodontal therapy (NSPT) in the glycated hemoglobin (HbA1c) control of type 2 diabetes (T2D) patients with periodontitis. PubMed, Cochrane, LILACS, Web of Science, Scopus, Embase, LIVIVO, and grey literature were searched. Risk of bias was assessed with the RoB v2.0 tool. A frequentist NMA assessed HbA1c improvement, through standardized mean difference under a random-effects model. Certainty of evidence was addressed through the GRADE (Grading of Recommendations, Assessment, Development and Evaluations) partially contextualized framework. Ten randomized controlled clinical trials were included, with 234 patients receiving alpha lipoic acid (ALA), cranberry juice, cranberry juice enriched with omega-3, fenugreek, ginger, grape seed, lycopene, melatonin, omega-3, propolis or vitamin C supplementation to NSPT, and 220 patients receiving NSPT alone or with placebo. Nine studies were meta-analyzed. HbA1c improved when NSPT was combined with propolis, ALA and melatonin supplementation (moderate-to-low certainty), compared to NSPT alone or with placebo. Risk of bias issues were found in eight studies. In conclusion, the use of propolis supplementation to NSPT probably results in HbA1c improvement in T2D patients with periodontitis (large effect with moderate certainty), while ALA and melatonin supplementation may contribute to reduce the HbA1c in T2D patients with periodontitis (large effects with low certainty).

A comprehensive insight into the molecular and cellular mechanisms of the effects of Propolis on preserving renal function: a systematic review

BACKGROUND

The present systematic review is conducted, focusing on the existing evidence of Propolis's effects due to its various health benefits, mainly antioxidant and anti-inflammatory properties on preserving renal function.

METHODS

A systematic search of PubMed, Scopus, Embase, ProQuest, and Google Scholar was undertaken for relevant papers published from the start until January 2021.

RESULTS

This review revealed that Propolis affects fasting blood sugar (FBS), postprandial blood glucose, advanced glycation end products (AGEs) concentrations, malondialdehyde (MDA) levels, urinary concentrations of reactive oxygen metabolites (Tbars), total oxidant status (TOS), oxidative stress index (OSI), and 8-hydroxy-2'-deoxyguanosine (8-OHdG) formation favorably. The findings on hemoglobin A1C (HbA1C), insulin, homeostasis model assessment of insulin resistance (HOMA-IR), β-cell function (HOMA-β), quantitative insulin sensitivity check index (QUICKI), and lipid profile were controversial. Moreover, a significant reduction in renal nuclear factor kappa B (NF-κB), serum immunoglobulins, renal ED-1+ cells, and urinary monocyte chemoattractant protein-1 (MCP-1) following Propolis supplementation has been reported, while the results on interleukin-6 (IL-6), tumor necrosis factor α (TNF-α), nitric oxide (NO), nitric oxide synthetase (NOS), and high sensitivity C-reactive protein (hs-CRP) were controversial. Furthermore, included studies showed its anti- proteinuria and kidney restoring effects.

CONCLUSION

In this review, both human and animal studies provide us evidences that Propolis could potentially improve the glycemic status, oxidative stress, renal tissue damage, and renal function. Further studies are needed to determine the underlying mechanisms.

Propolis: Chemical Constituents, Plant Origin, and Possible Role in the Prevention and Treatment of Obesity and Diabetes

Honeybee products are not only beneficial to human health but also important to the food industry. One such product is propolis, a resinous substance that honeybees collect from certain trees and plants and store inside their hives. Although various health benefits of propolis have been reported, the chemical composition of propolis varies greatly depending on the growing region and plant origin. These differences have led to many misconceptions and conflicting research results. In this paper, we review research findings on how the growing region and plant origin of propolis affects its composition. We also discuss trends in research on the antiobesity and antidiabetes effects of propolis as well as recent findings that a major component of Brazilian green propolis modulates adipocyte function. Finally, we discuss challenges to be tackled in future research on the health benefits of propolis and share our perspective on the future of this field.

The effects of propolis supplementation on metabolic parameters: A systematic review and meta-analysis of randomized controlled clinical trials

Objective:

Propolis is a sticky, resinous substance produced by honeybees from various plants. Various biological properties of propolis and its extracts have been recognized in previous studies including the antiseptic, anti-inflammatory, antioxidant, antiviral, hepatoprotective, antitumor, antibacterial and antimycotic properties. This study aimed to summarize the effect of propolis on metabolic parameters in human adults using systematic review and meta-analysis.

Materials and Methods:

A comprehensive systematic search was performed in ISI Web of Science, PubMed, Scopus, and Google Scholar up to July 2020 for controlled clinical trials evaluating the impact of propolis on lipid profile and liver enzyme biomarkers. A random effects model was used to calculate the weighted mean difference (WMD) and 95% confidence interval (CI) as the difference between the mean for the intervention and control groups.

Results:

The present meta-analysis included six randomized controlled trials. There was significant reduction in Aspartate Aminotransferase (AST) in comparison to the control groups (WMD=-2.01; 95% CI: -3.93--0.10; p=0.039). However, a non-significant effect was observed in Triglycerides (TG), Total cholesterol (TC), low-density lipoprotein (LDL), High-density lipoprotein (HDL) (WMD=-0.05 mg/dl; 95% CI: -0.27-0.18; p=0.688; WMD=7.08 mg/dl; 95% CI: -37.31-51.46; p=0.755; WMD=-0.94 mg/dl; 95% CI: -6.64-4.77; p=0.747; WMD=3.14 mg/dl; 95% CI: -1.84-8.13; p=0.216, respectively).

Conclusion:

Current meta-analysis revealed that propolis supplementation can reduce AST; nevertheless, there was no significant effect on lipid profile indices and ALT.

Metabolic products of European-type propolis. Synthesis and analysis of glucuronides and sulfates

ETHNOPHARMACOLOGICAL RELEVANCE

Propolis is a bee-derived product used since antiquity for its general health-giving properties and is especially noted for its anti-bacterial activity. In more recent times, propolis has been employed against more specific targets such as antiproliferative effects vs cancer cells, wound healing and type-2 diabetes.

AIM OF THE STUDY

European (poplar)-type propolis from New Zealand contains a number of hydroxy cinnamic acid esters and a set of aglycone flavonoid compounds, mainly chrysin, galangin, pinocembrin and pinobanksin. Propolis is usually taken orally and propolis metabolites quickly appear in the plasma of the ingested. In this work we aimed to identify the major flavonoid plasma metabolites by direct analysis of the plasma.

MATERIALS AND METHODS

After consumption of a large dose of propolis in a single sitting, blood samples were taken and analysed using LCMS/MS. The major flavonoid metabolites identified were also synthesised using chemical (sulfates) or enzymatic methods (glucuronides).

RESULTS

Both the sulfate and glucuronide conjugates of the four major propolis flavonoids are readily detected in human plasma after propolis ingestion. Preparation of the sulfates and glucuronides of the four major flavonoids allowed the relative proportions of the various metabolites to be determined. Although the sulfates are seen as large peaks in the LCMS/MS, the glucuronides are the dominant conjugate species.

CONCLUSIONS

This study shows most of the flavonoids in the plasma are present as 7-O-glucuronides with only galangin showing some di-glucuronidation (3,7-O-diglucuronide). No evidence was found for hydroxy cinnamic acid type metabolites in the plasma samples.

The effect of propolis supplementation on inflammatory factors and oxidative status in women with rheumatoid arthritis: Design and research protocol of a double-blind, randomized controlled

Backgrounds and aims

Rheumatoid arthritis (RA), is immune-inflammatory disease which is associated with great pain and disability. Overproduction of pro-inflammatory cytokines and oxidative stress play an important role in RA pathogenesis and related outcomes. The aim of this study was to evaluate the effects of propolis on inflammatory biomarkers and oxidative stress status in RA patients.

Methods/design

Randomized, placebo-controlled, and double-blind clinical trial aiming to recruit 48 patients with RA. Block randomization will be used. An intervention group will receive 500 mg/twice a day propolis capsules for 3 months and control group will receive the placebo for the same dose and duration. The oxidative stress status (malondialdehyde (MDA), total antioxidant capacity (TAC), total oxidant status (TOS), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx)), and inflammatory biomarkers (interleukin-17 (IL-17), Tumor necrosis factor alpha (TNF-α), High-sensitivity C-reactive protein (hs-CRP)), lipid profile (total cholesterol (TC), high density lipoprotein (HDL-c), low density lipoprotein (LDL-c), and triglyceride (TG)) and also physical activity, anthropometric indices, clinical and nutritional status will be measured at beginning and end of this study. The primary analysis will be based on theintention-to-treat principle.

Discussion

If this randomized clinical trial shows the reduction in inflammatory cytokines and oxidative stress and improves clinical outcome, it would provide evidence for other clinical trials to evaluate the efficacy of propolis supplementation in RA patients.

Effects of propolis supplementation on glycemic status, lipid profiles, inflammation and oxidative stress, liver enzymes, and body weight: a systematic review and meta-analysis of randomized controlled clinical trials

The aim of meta-analysis was to assess the effects of propolis on markers of oxidative stress, lipid profiles, inflammation and glycemic control, liver enzymes, and weight control. The heterogeneity between the included studies was indicated using the Cochrane's Q test and I-square (I2) statistic. 14 trials were included in this meta-analysis. Our meta-analysis indicated a significant reduction in fating glucose (WMD: -17.00; 95% CI: -30.88, -3.11), HbA1C (WMD: -0.42; 95% CI: -0.75, -0.10), and insulin (WMD: -1.75; 95% CI: -3.24, -0.26) and a marginally significant reduction in insulin resistance (WMD: -0.60; 95% CI: -1.20, 0.00) following propolis supplementation in 10, 8, 6, and 5 studies, respectively. Pooling 5 effect sizes, a significant reduction was seen in ALT (WMD: -5.63; 95% CI: -10.59, -0.67) and aspartate aminotransferase (AST) (WMD: -3.09; 95% CI: -5.15, -1.03) following propolis. A significant beneficial effect was observed for CRP (WMD: -1.11; 95% CI: -1.92, -0.29), TNF-α (WMD: -6.71; 95% CI: -9.44, -3.98) and interleukin-6 (IL-6) (WMD: -17.99; 95% CI: -35.56, -0.42) concentrations after propolis supplementation. This study demonstrated the beneficial effects of propolis on FPG, HbA1c, insulin, CRP, TNF-α and liver enzymes levels.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s40200-020-00696-w.

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.

To bee or not to bee? The bee extract propolis as a bioactive compound in the burden of lifestyle diseases

Propolis is a polyphenolic plant resin collected by bees to protect hives against pathogens and temperature drop. It exhibits antibacterial, antioxidant, and antiinflammatory properties. Propolis has been reported to possess antidiabetic properties and display beneficial effects against cardiovascular disease, gut dysbiosis, and chronic kidney disease. It has an excellent clinical safety profile, with no known toxic effects described so far. In this review, we discuss the salutogenic effects of propolis, with particular reference to modulating notable features of chronic kidney disease, notably those involving cardiovascular risks.

Protective effects of propolis on hepatic steatosis and fibrosis among patients with nonalcoholic fatty liver disease (NAFLD) evaluated by real-time two-dimensional shear wave elastography: A randomized clinical trial

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease, while no drugs have been approved for its treatment. The pieces of evidence indicate that propolis as a novel anti-inflammatory agent might be a promising candidate to treat NAFLD. We aimed to evaluate the efficacy of propolis on hepatic steatosis and fibrosis in patients with NAFLD. This randomized clinical trial was conducted on 54 patients with NAFLD. Patients were randomly assigned to receive propolis tablets at a dose of 250 mg twice daily for 4 months or placebo. The improvement in hepatic steatosis and fibrosis was evaluated using two-dimensional shear wave elastography. Improvement in the hepatic steatosis was significantly higher in the propolis group than the placebo group, even after adjustment for baseline value and changes in weight, energy intake, and physical activity (odds ratio [OR]: 5.67; 95% confidence intervals [CI]: 1.41-22.8; p = .014). A significant reduction was observed on the liver stiffness in the propolis group (-0.65 ± 0.56 kPa; p = .001), whereas it increased in the placebo group (0.27 ± 0.59 kPa; p = .037). Also, the intake of propolis significantly decreased high-sensitivity C-reactive protein (hs-CRP) levels compared with the placebo group (-0.371; 95%CI: -0.582 to -0.16 mg/L; p = .01). Changes in serum levels of fasting blood sugar, alanine aminotransferase, aspartate aminotransferase, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, cholesterol, and triglyceride did not differ significantly between the two groups (p > .05). There was no significant improvement in insulin resistance in both groups (p > .05). Propolis seems to have protective effects on hepatic steatosis and fibrosis and to reduce the serum levels of hs-CRP in patients with NAFLD.

Poplar Propolis Ethanolic Extract Reduces Body Weight Gain and Glucose Metabolism Disruption in High-Fat Diet-Fed Mice

SCOPE

Current evidence supports the beneficial effect of polyphenols on the management of obesity and associated comorbidities. This is the case for propolis, a polyphenol-rich substance produced by bees. The aim of the present study is to evaluate the effect of a poplar propolis ethanolic extract (PPEE) on obesity and glucose homeostasis, and to unveil its putative molecular mechanisms of action.

METHODS AND RESULTS

Male high-fat (HF) diet-fed mice are administered PPEE for 12 weeks. PPEE supplementation reduces the HF-mediated adiposity index, adipocyte hypertrophy, and body weight gain. It also improves HOMA-IR and fasting glucose levels. Gene expression profiling of adipose tissue (AT) shows an induction of mRNA related to lipid catabolism and mitochondrial biogenesis and inhibition of mRNA coding for inflammatory markers. Interestingly, several Nrf2-target genes are induced in AT following administration of PPEE. The ability of PPEE to induce the expression of Nrf2-target genes is studied in adipocytes. PPEE is found to transactivate the Nrf2 response element and the Nrf2 DNA-binding, suggesting that part of the effect of PPEE can be mediated by Nrf2.

CONCLUSION

PPEE supplementation may represent an interesting preventive strategy to tackle the onset of obesity and associated metabolic disorders.

Molecular and cellular mechanisms of the effects of Propolis in inflammation, oxidative stress and glycemic control in chronic diseases

Propolis is a sticky, resinous material gather from plants and is blended with wax and other constituents. It is reported to have anti-inflammatory, anti-oxidative and blood glucose-lowering properties. This review aims to summarise evidences for the cellular and molecular mechanism of Propolis in inflammation, oxidative stress, and glycemic control. Propolis stimulate the production and secretion of anti-inflammatory cytokines and to inhibit the production of inflammatory cytokines and due to its various antioxidant and poly-phenolic compounds may has a role in control and treating some of the chronic diseases. Most studies have shown that Propolis may affect metabolic factors including plasma insulin levels, and it has proposed that it could be used in the prevention and treatment of T2D Mellitus. In general, to demonstrate the definite effects of Propolis on chronic diseases, more studies are required using larger sample sizes and various doses of Propolis, using better characterized and standardized agents.

Does propolis affect the quality of life and complications in subjects with irritable bowel syndrome (diagnosed with Rome IV criteria)? A study protocol of the randomized, double-blinded, placebo-controlled clinical trial

BACKGROUND

Irritable bowel syndrome (IBS) is one of the most frequent and recurrent gastrointestinal diseases. However, up to now, no pharmacological agent has been approved to treat IBS. Emerging evidence showed that inflammation has a vital role in enhancing nervous system sensitivity and perception of abdominal pain in subjects with IBS. Propolis is an herbal substance with a broad spectrum of antioxidants, anti-inflammatory, and prebiotic properties, which might exert beneficial effects to reduce the severity of IBS. The current clinical trial aims to evaluate the efficacy of propolis supplementation on IBS.

METHODS

This single-center, randomized, double-blind, placebo-controlled clinical trial will be performed to evaluate the effect of propolis supplementation in adult patients with IBS diagnosed with Rome IV criteria. Fifty-two eligible patients will randomly be allocated to receive a propolis tablet (450 mg, containing 100 mg polyphenol compounds) or identical placebo, twice daily for 6 weeks. The primary outcome of the trial is an improvement in IBS severity from baseline to the sixth week of intervention. The secondary outcomes include the change in weight, waist circumference, and IBS quality of life. We will use the paired sample t test or Mann-Whitney U test for the within-group comparison and independent sample t test or Wilcoxon rank-sum and chi-square test or Fisher's exact test for the between-group comparison. Besides, a multivariable-adjusted mean effect will be computed using the ANCOVA test.

DISCUSSION

We hypothesize that propolis supplementation would be useful for treating IBS through its antioxidants, anti-inflammatory, and prebiotic properties. This trial will show the results of propolis supplementation, whether positive or negative, on IBS. If the current trial confirms our hypothesis, propolis supplementation can be a new choice in adjunctive therapy of IBS.

TRIAL REGISTRATION

Iranian Registry of Clinical Trials IRCT20190708044154N1. Registered on 26 December 2019. Updated on 13 February 2020. https://en.irct.ir/trial/40983 SPONSOR: Tabriz University of Medical Sciences, Tabriz, Iran.

The effect of okra (Abelmoschus esculentus) on lipid profiles and glycemic indices in Type 2 diabetic adults: Randomized double blinded trials

The aim of the present study was to investigate the effect of okra consumption on serum levels of lipid profiles and glycemic indices in Type 2 diabetic (T2D) patients. The present study was a randomized, double-blinded clinical trial, carried out in Kerman, Iran. Sixty T2D patients were randomized into intervention and control groups and received 10 g okra powder blended in 150 g conventional yogurt or conventional yogurt alone, along with dinner and lunch, for 8 weeks. Glycemic markers and lipid profile were assessed, as well as anthropometric measures, at the beginning and end of study. The findings showed that 8 weeks okra consumption resulted in a significant decrease in fasting plasma glucose (-15.61 ± 19.44 vs. -3.40 ± 24.78; p = .02), homeostatic model of assessment for insulin resistance (-1.17 ± 1.61 vs. -0.14 ± 1.64; p = .01), quantitative insulin sensitivity check index (0.01 ± 0.007 vs. 0.00 ± 0.01; p = .004), triacylglycerol (-22.30 ± 32.46 vs. -3.86 ± 30.57; p = .001), total cholesterol (-10.23 ± 10.36 vs. -2.03 ± 13.94; p = .004), low-density lipoprotein cholesterol (LDL-C; -8.15 ± 10.01 vs. -2.31 ± 9.37; p = .02), and LDL-C/high-density lipoprotein cholesterol (HDL-C) ratio (-0.28 ± 0.37 vs. -0.08 ± 0.24; p = .01). No significant difference was observed between groups in HDL-C, glycated hemoglobin, fasting insulin levels, and anthropometric measures. The present study suggests that okra consumption can elicit improvements in lipid profile, as well as glycemic markers, among T2D patients.

The efficacy of sour tea (Hibiscus sabdariffa L.) on selected cardiovascular disease risk factors: A systematic review and meta-analysis of randomized clinical trials

This study sought to summarize clinical evidence of sour tea (Hibiscus sabdariffa L.) administration on cardiovascular disease risk factors. PubMed, Scopus, Institute for Scientific Information Web of Science, and Google Scholar were systematically searched from inception to June 2019 to identify randomized clinical trials, which assessed the effect of sour tea consumption on lipid profiles, fasting plasma glucose, and blood pressure in adult populations. Mean and standard deviation for each parameter were extracted to calculate effect size. Cochrane Collaboration tools were used to evaluate risk of bias assessment. A total of seven randomized clinical trials consisting 362 participants were included in the meta-analysis. Pooled effect size demonstrated that sour tea consumption significantly reduces fasting plasma glucose (-3.67 mg/dl, 95% confidence interval, CI [-7.07, -0.27]; I² = 37%), systolic blood pressure (-4.71 mmHg, 95% CI [-7.87, -1.55]; I² = 53%), and diastolic blood pressure (-4.08 mmHg, 95% CI [-6.48, -1.67]; I² = 14%). Although no significant effect was observed on triacylglycerol, total cholesterol, and high-density lipoprotein cholesterol following sour tea consumption, a trend toward a significant reduction was found in low-density lipoprotein cholesterol serum concentrations (p = 0.08). This systematic review and meta-analysis suggests that sour tea consumption could have beneficial effect in controlling glycemic status and blood pressure among adult population.

Caffeic acid phenethyl ester (CAPE): pharmacodynamics and potential for therapeutic application

Caffeic acid phenethyl ester (CAPE) is the major pharmacologically-active component of some propolis types, rich in polyphenols, such as poplar propolis types. CAPE has the potential to be applied as a pharmaceutical as it possesses most of the pharmacological activities of propolis, such as anti-proliferative, antioxidant, immunomodulatory, antidiabetic, anti-inflammatory and antimicrobial. Its advantage is that it lacks some of the downsides of total propolis extracts, such as inability for unified standardization, which is cornerstone for implementing its therapeutic potential as a drug. The current paper provides an overview on the pharmacodynamic principles of CAPE. We present literature search outcomes form ClinicalTrials.gov database and from scientific publications, available on Scopus and Crossref databases. We take a round view of CAPE’s potential therapeutic implications in light of approved drugs with related modes of action.