Effects of zinc supplementation on sleep quality in humans: A systematic review of randomized controlled trials.

Background and Aims: Alternative therapies, such as zinc supplementation, have been explored as potential interventions for sleep disorders. However, the efficacy of zinc supplementation in improving sleep quality remains uncertain. This systematic review aims to examine the impacts of zinc supplementation on sleep quality in humans. Methods: The Web of Science, Medline, Scopus, and Google Scholar databases were comprehensively searched to find studies investigating the effect of zinc supplementation on sleep quality. After identifying relevant studies by screening, relevant data were extracted from them. The quality assessment was conducted using the Cochrane quality assessment tool. Results: This systematic review included eight studies. The interventions ranged from 4 to 48 weeks, with a daily dose of zinc supplementation varying between 10 and 73.3 mg. The majority of the evidence examined in this review pointed to the significant improvement effect of zinc supplementation on sleep quality in adults compared to the control groups. Furthermore, zinc supplementation did not have a significant effect on sleep disorders. However, there was no consensus about these findings. Also, the effect of supplementation on sleep duration in nonadults was contradictory. Conclusions: This systematic review suggests that zinc supplementation may lead to improvements in sleep quality. However, more research, primarily clinical trials, is needed to clarify the beneficial effects of zinc supplementation on sleep quality with consideration of dietary zinc intake and the Recommended Dietary Allowances of zinc (RDA) in the different populations. It is also recommended to investigate the effect of zinc supplementation on sleep quality in people with zinc deficiency in future studies.

Effects of Propolis Consumption on Liver Enzymes and Obesity Indices in Adults: A Systematic Review and Dose-Response Meta-Analysis.

Background: Propolis, a natural resin produced by bees, has been studied for its potential effects on liver enzymes and obesity indices. However, a meta-analysis is necessary to comprehensively understand the impact of propolis on obesity and liver function. Objectives: This meta-analysis of randomized controlled trials (RCTs) sought to evaluate the effects of propolis consumption on liver enzymes and obesity indices in adults. Methods: A systematic literature search up to December 2023 was completed in PubMed/Medline, Scopus, and Web of Science, to identify eligible RCTs. Heterogeneity tests of the selected trials were performed using the I 2 statistic. Random-effects models were assessed on the basis of the heterogeneity tests, and pooled data were determined as weighted mean differences (WMDs) with a 95% confidence interval (CI). Results: A pooled analysis of 24 trials showed that propolis consumption led to a significant reduction in alanine aminotransferase (ALT) (WMD: -2.58; 95% CI: -4.64, -0.52; P = 0.01), aspartate aminotransferase (AST) (WMD: -1.84; 95% CI: -3.01, -0.67; P = 0.002), and alkaline phosphatase (ALP) (WMD: -24.90; 95% CI: -42.13, -7.67; P = 0.005) in comparison with the control group. However, there were no significant effects on gamma-glutamyl transferase (GGT), body weight, BMI (in kg/m2), fat mass, body fat percentage, fat-free mass, adiponectin, waist circumference, hip circumference, and waist-hip ratio in comparison with the control group. Conclusions: We discovered that consuming propolis can lead to a significant decrease in ALT, AST, and ALP levels, without causing significant changes in GGT, anthropometric indices, and adiponectin levels. However, future well-designed RCTs with large numbers of participants and extended durations, focusing on precise propolis dosage and ingredients, are necessary.

The Effects of Raspberry Consumption on Glycemic Control and Inflammation Markers in Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Despite observing the health benefits of raspberry consumption in some recent studies, there is still no consensus regarding this effectiveness on inflammatory markers and glycemic control. This study aimed to investigate this effectiveness by performing a meta-analysis. The PubMed, Web of Science, and Scopus databases were comprehensively searched until December 2023 to find relevant randomized controlled trials. Eligible studies were screened, and relevant information was extracted. The overall effect size of raspberry consumption on each of the outcomes was estimated by following the random-effects model in the form of a 95% confidence interval (CI) and a weighted mean difference (WMD). Raspberry consumption led to a significant increase in insulin concentrations (WMD: 1.89 µU/mL; 95%CI: 1.45, 2.34; P < 0.001) and a significant decrease in tumor necrosis factor-α (TNF-α) concentrations (WMD: -3.07 pg/mL; 95%CI: -5.17, -0.97; P = 0.004), compared with the control groups. Raspberry consumption did not have a significant effect on fasting blood glucose, insulin, hemoglobin A1C, glucose tolerance tests, homeostatic model assessment for insulin resistance, C-reactive protein, and interleukin-6 concentrations. This review revealed that raspberry consumption led to a significant increase and decrease in insulin and TNF-α concentrations, respectively. However, to draw a more accurate conclusion, it is necessary to conduct studies with a larger sample size in the future. The current study's protocol has been registered in the PROSPERO system as CRD42023477559.

The effects of raspberry consumption on lipid profile and blood pressure in adults: A systematic review and meta-analysis.

Research into the effects of raspberry on blood pressure and lipid profiles is inconclusive. This meta-analysis was aimed to determine whether raspberry has beneficial effects in clinical practice and to what extent these effects are associated with blood pressure and lipid profiles. A systematic literature search up to September 2023 was completed in PubMed/Medline, Scopus, and Web of Science, to identify eligible RCTs. Heterogeneity tests of the selected trials were performed using the I 2 statistic. Random effects models were evaluated based on the heterogeneity tests, and pooled data were determined as weighted mean differences with a 95% confidence interval. Eleven randomized controlled trials (with 13 arms) were eligible for this meta-analysis. Our findings revealed that Raspberry consumption had no significant effects on the blood pressure and lipid profile markers, including systolic blood pressure (SBP) (WMD, -0.37 mm Hg; 95%CI: -2.19 to 1.44; p = .68), diastolic blood pressure (DBP) (WMD, -2.14 mm Hg; 95%CI: -4.27 to 0.00; p = .05), total cholesterol (TC) (WMD, -6.83 mg/dL; 95%CI: -15.11 to 1.44; p = .10), triglycerides (TG) (WMD, -5.19 mg/dL: 95%CI: -11.76 to 1.37; p = .12), low-density lipoprotein-cholesterol (LDL-C) (WMD, -5.19 mg/dL; 95%CI: -11.58 to 1.18; p = .11), and high-density lipoprotein-cholesterol (HDL-C) (WMD, 0.82 mg/dL; 95%CI: -1.67 to 3.32; p = .51), compared to control groups. Subgroup analysis showed that raspberry consumption significantly decreased total cholesterol and LDL-C levels in people with elevated TC levels, metabolic syndrome, and andropause symptoms, as well as those older than 35, while the consumption of raspberries led to a significant increase in HDL-C levels in females, obese, under 35, and healthy individuals. Raspberry can improve lipid profile and blood pressure, but it is important to keep in mind that further research is necessary to fully understand the exact mechanism of action and a definite conclusion in this regard.

The effect of pomegranate juice supplementation on C-reactive protein levels: GRADE-assessed systematic review and dose-response updated meta-analysis of data from randomized controlled trials.

Pomegranate juice (PJ) has a possible anti-inflammatory effect because of its polyphenol content and antioxidants. However, the anti-inflammatory effect of PJ in randomized controlled trials (RCTs) has not been consistent. A previous meta-analysis conducted in 2016 reported a nonsignificant lowering effect of PJ on C-reactive protein (CRP) levels. This systematic review and meta-analysis aim to update the pooled effect size of PJ supplementation on CRP levels in RCT studies. PubMed, Scopus, and Web of Science databases were comprehensively searched until July 2023. Eligible studies were found by screening, their relevant data was extracted, and a risk of bias assessment was performed. The pooled effect size was calculated using a random effect model as the weighted mean difference (WMD) with a 95% confidence interval. This systematic review included 11 studies with 13 effect sizes and 696 participants. Meta-analysis showed that PJ supplementation led to a significant decrease in CRP levels compared to control groups (WMD: -2.55 mg/L; 95%CI: -3.44 to -1.66; p < 0.001). Subgroup analysis demonstrated the significant reduction effect of PJ on CRP levels in studies conducted on the both sexes or only females as well as Iranian population, individuals with 40 years≤, type 2 diabetes, polycystic ovary syndrome, or trials that intervened with PJ dosage of <250 ml/day. Meta-regression and dose-response analysis reported a nonsignificant linear and nonlinear relationship between intervention characteristics (duration and dose of PJ) and CRP changes. The current meta-analysis revealed that PJ supplemantation has a beneficial effect in improving CRP levels. It is recommended to understand this effect better, and find the optimal dose and duration of PJ supplementation to reduce CRP levels in the blood, and repeat meta-analysis after related RCTs are available. For the final proof of these effects, more detailed human studies are needed.

The effect of Royal jelly on liver enzymes and glycemic indices: A systematic review and meta-analysis of randomized clinical trials.

BACKGROUND: Royal jelly (RJ) may contribute to glycemic control and liver function through various mechanisms. The present study aimed to quantify the effect of RJ supplementation on these outcomes. METHODS: A literature search of Web of Science, Scopus, and PubMed/Medline, was conducted for RCTs investigating the efficacy of RJ on plasma liver enzymes and glycemic indices. Weighted mean differences (WMDs) and 95% confidence intervals (CIs) were calculated for net changes using a random-effects model. RESULTS: Ten RCTs were selected for inclusion in this meta-analysis. Combined estimate of effect sizes for the impact of RJ on neither the plasma liver enzymes nor the glycemic indices were statistically significant. Subgroup analysis showed a significant reduction of serum FPG in trials with intervention duration ≥ 8 weeks (WMD: -4.28 mg/dl, 95% CI -7.41 to -1.14 mg/dl, p = 0.007), and those conducted in non-healthy populations (WMD: -4.28 mg/dl, 95% CI -7.41 to -1.14, p = 0.007). CONCLUSION: RJ does not significantly affect liver function and glycemic profile of adult population. In trials with longer intervention and those conducted in non-healthy populations a significant reduction of serum FBG was observed. This meta-analysis should be repeated in the future, with more primary articles included, in order to provide conclusive results.