Pomegranate juice intake enhances the effects of aerobic training on insulin resistance and liver enzymes in type 2 diabetic men: a single-blind controlled trial

Impact of Combined Aerobic Training and Magnesium Supplementation on Serum Biomarkers and microRNA-155 and microRNA-21 Expression in Adipose Tissue of Type 2 Diabetic Rats: An Eight-Week Interventional Study

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a complex metabolic disorder characterized by insulin resistance and chronic inflammation. Aerobic training (AT) and magnesium supplementation (Mg) have both been independently shown to have beneficial effects on glucose control and insulin sensitivity in individuals with T2DM. However, the potential synergistic effects of combining AT and Mg supplementation have not been extensively studied. This study aimed to investigate the effects of an 8-week AT and Mg supplementation on serum levels of insulin, glucose, leptin, adiponectin, TNF-α, IL-1β, IL-6, NF-κB, as well as the expression of mir-155 and mir-21 in the visceral adipose tissue (VAT) of rats with T2DM.

METHODS

For this experimental study, 32 male Wistar rats were induced with T2DM by a high-fat diet combined with a low-dose streptozotocin injection. The rats were randomly assigned to four groups: AT and Mg supplementation (AT + Mg), AT (5 days/week for 8 weeks), Mg supplementation (received daily supplementation of Mg chloride), and diabetic control (C). An 8-week AT program was implemented, with gradually increasing the intensity and duration to reach 25 m/min and 60 min in the 8th week, respectively. The training intensity was set at 50-60% of VO2max. The Mg groups were provided with rat diets containing 1000 mg/kg of Mg. The AT + Mg group received both interventions, while the C group served as the untreated control. Serum biomarkers were measured using enzyme-linked immunosorbent assay (ELISA), and VAT samples were collected for gene expression analysis using real-time polymerase chain reaction (PCR).

RESULTS

Serum biomarker analysis revealed that the AT + Mg group had a significant decrease in fasting insulin (p = 0.001) and serum glucose (p = 0.001), as well as an increase in adiponectin levels compared to the C group (p = 0.002). Additionally, the AT + Mg group showed a significant reduction in serum leptin, TNF-α, IL-6, IL-1β, and NF-κB, as well as downregulation of mir-155 and mir-21 in the VAT compared to the other groups. The AT group also showed improvements in several parameters, while the Mg group had fewer significant differences compared to the C group.

CONCLUSION

The combination of AT and Mg supplementation provides a synergistic effect that improves serum biomarkers and downregulates pro-inflammatory microRNAs in the VAT of T2DM rats. Meanwhile, Mg supplementation alone does not have a significant effect on pro-inflammatory microRNAs in the VAT. These findings suggest that such combined interventions could be a promising strategy for managing T2DM, potentially ameliorating inflammatory states and improving metabolic health.

Lack of Efficacy of Pomegranate Supplementation on Insulin Resistance and Sensitivity: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

The objective of this study is to assess the impact of pomegranate supplements on insulin resistance (IR) and insulin sensitivity through a systematic review and meta-analysis of randomized controlled trials (RCTs). Additionally, we aim to analyze the differences in efficacy among various pomegranate extracts and the sensitivity of different diseases to pomegranate supplementation. We conducted searches in PubMed, Embase, Web of Science, and Cochrane Library up to October 30, 2023, for relevant studies published in English. The treatment group required the intake of pomegranate extract for a minimum of 4 weeks, with no restrictions on the extract type. The control group received a placebo or a treatment excluding pomegranate extract. The primary outcome was homeostatic model assessment for insulin resistance (HOMA-IR) and fasting insulin (FI), and the secondary outcome was quantitative insulin sensitivity check index (QUICKI). RoB 2 was used to assess the risk of bias in the original studies. We pre-specified subgroup analyses based on types of intervention, intervention duration, health condition, and intervention dose. Sensitivity analysis was conducted to validate result stability, utilizing Begg's test and Egger's test for publication bias. Data synthesis and analysis were performed using Stata 15.1 software. This study included a total of 15 RCTs with 673 participants conducted in 7 countries. Risk of bias results indicated an overall low risk of bias of the articles. Participants included healthy individuals, overweight and obese individuals, non-alcoholic fatty liver disease (NAFLD) patients, type 2 diabetes (T2DM) patients, polycystic ovary syndrome (PCOS) patients, metabolic syndrome (MS) patients, and individuals with hyperlipidemia. Pomegranate extract variations included pomegranate juice (PJ), pomegranate seed oil (PSO) capsule, pomegranate/pomegranate peel (PP) extract capsule, and pomegranate peel-added bread. The control groups primarily received placebo treatments with varying dosage and frequency. No adverse reactions were reported in any of the studies. The summary results showed that compared to the control groups, pomegranate extract had no significant impact on improving HOMA-IR levels in participants (WMD = -0.03, 95%CI: -0.37 to 0.31, and p = 0.851) and FI (WMD = -0.03, 95%CI: -0.42 to 0.36, and p = 0.862). Additionally, there was no significant advantage of pomegranate extract on QUICKI changes in T2DM and PCOS patients (WMD = 0.00, 95%CI: 0.00 to 0.01, and p = 0.002). Subgroup analysis results indicated that pomegranate extract could improve HOMA-IR levels in PCOS patients (WMD = -0.42, 95%CI: -0.54 to -0.29, and p < 0.001) and FI levels in T2DM, PCOS, and NAFLD patients. Our results indicate that pomegranate extract only improves HOMA-IR and FI levels in PCOS patients and FI levels in T2DM and NAFLD patients. No significant difference has been found for HOMA-IR, FI, or QUICKI in other metabolic diseases. The current evidence suggests that we should interpret the value of pomegranate extract in regulating IR and sensitivity cautiously. In the future, there is a need for more rigorously designed RCTs to specifically evaluate the impact of pomegranate supplementation on insulin sensitivity in patients with NAFLD, PCOS, and T2DM.

The effects of pomegranate consumption on liver function enzymes in adults: A systematic review and meta-analysis

BACKGROUND

We performed a systematic review and meta-analysis of all published clinical trial studies to provide a more accurate estimation of pomegranate effects on liver enzymes in different clinical conditions.

METHODS

A systematic literature search was carried out using electronic databases, including PubMed, Web of Science, and Scopus, up to March 2023 to identify eligible randomized clinical trials (RCTs) evaluating the effect of pomegranate consumption on liver function enzymes. Heterogeneity tests of the selected trials were performed using the I2 statistic. Random effects models were assessed based on the heterogeneity tests, and pooled data were determined as the weighted mean difference with a 95% confidence interval.

RESULTS

Out of 3811 records, 9 eligible RCTs were included in the current study. However, there are limitations in the included studies, which can be mentioned in the dose, duration, and type of interventions that are different among the studies, as well as the small number of included studies. All this causes heterogeneity among studies and this heterogeneity limits the consistency of the results. Our meta-analysis showed that pomegranate intake had a significant effect on lowering aspartate aminotransferase (AST) levels in long-term intervention (> 8 weeks), obese (BMI≥30) individuals, or patients with metabolic disorders. Furthermore, results showed a significant decrease in alanine aminotransferase (ALT) levels in the long-term intervention (> 8 weeks) or in patients with metabolic disorders following the pomegranate intake. Combined results from the random-effects model indicated a significant reduction in gamma-glutamyl transferase (GGT) levels (WMD: -5.43 IU/L 95% CI: -7.78 to -3.08; p < 0.001;) following the pomegranate intake. The results of Egger's test mentioned a significant publication bias for the trials examining the effect of pomegranate intake on AST (p = 0.007) and ALT (p = 0.036).

CONCLUSION

Our results suggest that long-term pomegranate intake may be effective in ameliorating liver enzymes in adults with obesity and metabolic disorders who are more likely to have elevated baseline liver enzymes due to some degree of liver injury or tissue damage. However, some studies failed to conduct independent biochemical characterization of the product used, including the presence and quantity of polyphenols, antioxidants, and proanthocyanidins.

Consumption of 100% Fruit Juice and Body Weight in Children and Adults: A Systematic Review and Meta-Analysis

Importance

Concerns have been raised that frequent consumption of 100% fruit juice may promote weight gain. Current evidence on fruit juice and weight gain has yielded mixed findings from both observational studies and clinical trials.

Objective

To synthesize the available evidence on 100% fruit juice consumption and body weight in children and adults.

Data Sources

MEDLINE, Embase, and Cochrane databases were searched through May 18, 2023.

Study Selection

Prospective cohort studies of at least 6 months and randomized clinical trials (RCTs) of at least 2 weeks assessing the association of 100% fruit juice with body weight change in children and adults were included. In the trials, fruit juices were compared with noncaloric controls.

Data Extraction and Synthesis

Data were pooled using random-effects models and presented as β coefficients with 95% CIs for cohort studies and mean differences (MDs) with 95% CIs for RCTs.

Main Outcomes and Measures

Change in body mass index (BMI; calculated as weight in kilograms divided by height in meters squared) was assessed in children and change in body weight in adults.

Results

A total of 42 eligible studies were included in this analysis, including 17 among children (17 cohorts; 0 RCTs; 45 851 children; median [IQR] age, 8 [1-15] years) and 25 among adults (6 cohorts; 19 RCTs; 268 095 adults; median [IQR] age among cohort studies, 48 [41-61] years; median [IQR] age among RCTs, 42 [25-59]). Among cohort studies in children, each additional serving per day of 100% fruit juice was associated with a 0.03 (95% CI, 0.01-0.05) higher BMI change. Among cohort studies in adults, studies that did not adjust for energy showed greater body weight gain (0.21 kg; 95% CI, 0.15-0.27 kg) than studies that did adjust for energy intake (-0.08 kg; 95% CI, -0.11 to -0.05 kg; P for meta-regression <.001). RCTs in adults found no significant association of assignment to 100% fruit juice with body weight but the CI was wide (MD, -0.53 kg; 95% CI, -1.55 to 0.48 kg).

Conclusion and Relevance

Based on the available evidence from prospective cohort studies, in this systematic review and meta-analysis, 1 serving per day of 100% fruit juice was associated with BMI gain among children. Findings in adults found a significant association among studies unadjusted for total energy, suggesting potential mediation by calories. Further trials of 100% fruit juice and body weight are desirable. Our findings support guidance to limit consumption of fruit juice to prevent intake of excess calories and weight gain.

The effects of pomegranate consumption on glycemic indices in adults: A systematic review and meta-analysis

BACKGROUND AND AIM

Epidemiologic studies have shown that type 2 diabetes (T2D) is more prevalent worldwide; therefore, improving glycemic indices to prevent or control T2D is vital. Randomized controlled trials (RCTs) on the effects of pomegranate consumption on glycemic indices have shown inconsistent results. Therefore, we aim to evaluate the impact of pomegranate consumption on fasting blood glucose (FBG), fasting insulin, hemoglobin A1c (HbA1c), and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) in adults.

METHODS

A systematic literature search was performed using electronic databases, including PubMed, Web of Science, and Scopus, up to May 2023 to identify eligible RCTs evaluating the effect of pomegranate consumption on glycemic indices. Heterogeneity tests of the included trials were performed using the I2 statistic. Random effects models were assessed based on the heterogeneity tests, and pooled data were determined as the weighted mean difference with a 95 % confidence interval.

RESULTS

Of 1999 records, 32 eligible RCTs were included in the current study. Our meta-analysis of the pooled findings showed that pomegranate consumption significantly reduced FBG (WMD: -2.22 mg/dL; 95 % CI: -3.95 to -0.50; p = 0.012), fasting insulin (WMD: -1.06 μU/ml; 95%CI: -1.79 to -0.33; p = 0.004), HbA1c (WMD: -0.22 %; 95% CI: -0.43 to -0.01; p = 0.037), and HOMA-IR (WMD: -0.30; 95%CI: -0.61 to -0.00; p = 0.046).

CONCLUSION

Overall, the results demonstrated that pomegranate consumption benefits glycemic indices in adults. However, further research with long-term interventions is required.

PROSPERO REGISTRATION CODE

CRD42023422780.

A review of experimental and clinical studies on the therapeutic effects of pomegranate (Punica granatum) on non-alcoholic fatty liver disease: Focus on oxidative stress and inflammation

Non-alcoholic fatty liver disease (NAFLD) is frequently linked to metabolic disorders and is prevalent in obese and diabetic patients. The pathophysiology of NAFLD involves multiple factors, including insulin resistance (IR), oxidative stress (OS), inflammation, and genetic predisposition. Recently, there has been an emphasis on the use of herbal remedies with many people around the world resorting to phytonutrients or nutraceuticals for treatment of numerous health challenges in various national healthcare settings. Pomegranate (Punica granatum) parts, such as juice, peel, seed and flower, have high polyphenol content and is well known for its antioxidant capabilities. Pomegranate polyphenols, such as hydrolyzable tannins, anthocyanins, and flavonoids, have high antioxidant capabilities that can help lower the OS and inflammation associated with NAFLD. The study aimed to investigate whether pomegranate parts could attenuate OS, inflammation, and other risk factors associated with NAFLD, and ultimately prevent the development of the disease. The findings of this study revealed that: 1. pomegranate juice contains hypoglycemic qualities that can assist manage blood sugar levels, which is vital for avoiding and treating NAFLD. 2. Polyphenols from pomegranate flowers increase paraoxonase 1 (PON1) mRNA and protein levels in the liver, which can help protect liver enzymes and prevent NAFLD. 3. Punicalagin (PU) is one of the major ellagitannins found in pomegranate, and PU-enriched pomegranate extract (PE) has been shown to inhibit HFD-induced hyperlipidemia and hepatic lipid deposition in rats. 4. Pomegranate fruit consumption, which is high in antioxidants, can decrease the activity of AST and ALT (markers of liver damage), lower TNF-α (a marker of inflammation), and improve overall antioxidant capacity in NAFLD patients. Overall, the polyphenols in pomegranate extracts have antioxidant, anti-inflammatory, hypoglycemic, and protective effects on liver enzymes, which can help prevent and manage NAFLD effects on liver enzymes, which can help prevent and manage NAFLD.

Effect of fruit on glucose control in diabetes mellitus: a meta-analysis of nineteen randomized controlled trials

Objective

Diabetes mellitus is a worldwide health problem, and it remains unclarified whether fruit is beneficial in glycemic control. This study aimed to analyze evidence from randomized controlled trials evaluating the effect of fruit consumption on glucose control.

Methods

We searched the PubMed, EMBASE, Ovid, Web of Science, and Cochrane Central Register of Controlled Trials databases from the respective database inception dates to December 30, 2022, to identify randomized controlled trials that evaluated the effects of fruit consumption on glucose control. Two researchers independently screened the studies in accordance with the inclusion and exclusion criteria, and performed the literature quality evaluation and data extraction. RevMan 5.4 software was used to perform the data analysis.

Results

Nineteen randomized controlled trials with 888 participants were included. Fruit consumption significantly decreased the fasting blood glucose concentration (MD -8.38, 95% CI -12.34 to -4.43), but it showed no significant difference in the glycosylated hemoglobin (MD -0.17, 95% CI -0.51 to 0.17). Subgroup analyses further suggested that the consumption of both fresh and dried fruit decreased the fasting blood glucose concentration.

Conclusions

Increasing the fruit intake reduced fasting blood glucose concentration. Therefore, we recommend that patients with diabetes eat more fruits while ensuring that their total energy intake remains unchanged.

Impact of Pomegranate Juice on the Pharmacokinetics of CYP3A4- and CYP2C9-Mediated Drugs Metabolism: A Preclinical and Clinical Review

The Punica granatum L. (pomegranate) fruit juice contains large amounts of polyphenols, mainly tannins such as ellagitannin, punicalagin, and punicalin, and flavonoids such as anthocyanins, flavan-3-ols, and flavonols. These constituents have high antioxidant, anti-inflammatory, anti-diabetic, anti-obesity, and anticancer activities. Because of these activities, many patients may consume pomegranate juice (PJ) with or without their doctor's knowledge. This may raise any significant medication errors or benefits because of food-drug interactions that modulate the drug's pharmacokinetics or pharmacodynamics. It has been shown that some drugs exhibited no interaction with pomegranate, such as theophylline. On the other hand, observational studies reported that PJ prolonged the pharmacodynamics of warfarin and sildenafil. Furthermore, since it has been shown that pomegranate constituents inhibit cytochrome P450 (CYP450) activities such as CYP3A4 and CYP2C9, PJ may affect intestinal and liver metabolism of CYP3A4 and CYP2C9-mediated drugs. This review summarizes the preclinical and clinical studies that investigated the impact of oral PJ administration on the pharmacokinetics of drugs that are metabolized by CYP3A4 and CYP2C9. Thus, it will serve as a future road map for researchers and policymakers in the fields of drug-herb, drug-food and drug-beverage interactions. Preclinical studies revealed that prolonged administration of PJ increased the absorption, and therefore the bioavailability, of buspirone, nitrendipine, metronidazole, saquinavir, and sildenafil via reducing the intestinal CYP3A4 and CYP2C9. On the other hand, clinical studies are limited to a single dose of PJ administration that needs to be protocoled with prolonged administration to observe a significant interaction.