The effects of cinnamon supplementation on adipokines and appetite-regulating hormones: A systematic review of randomized clinical trials.

Objective: Cinnamon is extracted from the inner bark of Cinnamomum trees. Recent studies have indicated that cinnamon is a safe and cost-effective treatment for improving body weight, lipid profiles, insulin resistance, and blood pressure. This systematic review aimed to summarize the effect of cinnamon supplementation on adipokines and appetite-regulating hormones. Materials and Methods: This comprehensive literature search was conducted using databases such as PubMed, Scopus, ISI Web of Science, and Google Scholar up to March 2022 without any limitation. The quality of eligible studies was evaluated through the Cochrane Collaboration's tool for assessing the risk of bias. Results: This systematic review included six clinical trial studies (363 participants), among which, only one study was performed on children, and two investigations were conducted on obese participants. A decreasing effect was found in the level of leptin and visfatin after cinnamon supplementation. Two out of three studies examined adiponectin levels and revealed non-significant effects of cinnamon consumption on this parameter. Two studies evaluated ghrelin levels and found an increase after cinnamon supplementation. The result of cinnamon supplementation on other biomarkers such as glucose-dependent insulinotropic polypeptide, glucagon-like peptide 1, and resistin was inconsistent. Conclusion: The result of this systematic review indicated the increasing effect of cinnamon supplementation on ghrelin levels and decreasing effect on leptin and visfatin levels. However, more clinical data are required to clarify the beneficial effects of cinnamon on adipokines levels due to the controversial findings of the studies.

A systematic review of randomized controlled trials related to the effects of garlic supplementation on platelet aggregation.

The increment of platelet aggregation factors has been considered a key phenomenon in atherosclerosis. Studies have shown that garlic (Allium sativum) is associated with a reduction in platelet aggregation and thrombosis. Hence, the present systematic review was conducted to evaluate the effect of garlic on platelet aggregation. All randomized controlled trials (RCTs) with keywords related to garlic and platelet aggregation were thoroughly searched in electronic databases including PubMed, Scopus, ISI Web of Science, and Google Scholar up to January 2021. Moreover, the references of all related articles were screened to discover more relevant studies. The quality of each study was reported based on Cochrane Collaboration's tool. In total, 12 studies met the inclusion criteria from 18,235 identified articles (including 595 participants). Most of the studies assessed platelet aggregation in response to different inducers. Of the 12 clinical trials, six studies depicted the beneficial effect of garlic on reducing platelet aggregation. The summary of the quality assessment indicated that most of the studies had high-quality scores. Regarding the small number of RCTs and heterogeneity between studies, it is impossible to make a proper conclusion about the impacts of garlic on platelet aggregation. Therefore, further precise trials with a standard design are necessary to validate the anti-thrombotic effect of garlic.

The role of Pycnogenol in the control of inflammation and oxidative stress in chronic diseases: Molecular aspects.

The prevalence of chronic diseases has increased significantly with the rising trend of sedentary lifestyles, reduced physical activity, and dietary modifications in recent decades. Inflammation and oxidative stress play a key role in the pathophysiology of several chronic diseases, such as type II diabetes, cardiovascular diseases, and hepatic conditions. Therefore, reducing inflammation and oxidative stress may be beneficial in the prevention and treatment of various chronic disorders. Since chronic diseases are not completely curable, various methods have been proposed for their control. Complementary therapies and the use of natural antioxidant and antiinflammatory compounds are among these novel approaches. Pycnogenol (PYC) is a natural compound that could control inflammation and oxidative stress. Furthermore, some previous studies have shown that PYC could effectively reduce inflammation through signaling the downstream of insulin receptors, inhibiting the phosphorylation of the serine residues of insulin receptor substrate-1, reducing pro-inflammatory cytokines and oxidative stress indices through the stimulation of antioxidant pathways, increasing free radical scavenging activities, preventing lipid peroxidation, and protecting the erythrocytes in glucose-6-phosphate dehydrogenase-deficient individuals, although these effects have not been fully proved. The present study aimed to comprehensively review the evidence concerning the positive physiological and pharmacological properties of PYC, with an emphasis on the therapeutic potential of this natural component for enhancing human health.

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.

Effect of kefir beverage consumption on glycemic control: A systematic review and meta-analysis of randomized controlled clinical trials.

Kefir is a fermented beverage obtained as a result of lactic-alcoholic fermentation of milk by using kefir grains or a starter culture. Kefir beverage has numerous health benefits owing to its antimicrobial, anti-inflammatory and anti-diabetic properties, while it could also regulate the gut microbiota. This beverage is recommended as a nutritional approach to glycemic control. This systematic review and meta-analysis of randomized controlled trials (RCTs) aimed to evaluate the effects of kefir beverage on the glycemic control. For this purpose, a literature search was conducted via databases such as PubMed, Scopus, ISI Web of Science, and Google Scholar for the articles published until July 2020 with no limitation. The indicators of glycemic control were fasting blood sugar (FBS), hemoglobin A1c (HbA1c), and insulin. In total, six RCTs on a total sample size of 323 subjects were selected for the meta-analysis. Inverse-variance weighted mean difference (WMD) with a 95% confidence interval (CI) was calculated for the mean changes in HbA1c, FBG and insulin compared to baseline. Considering the clinical heterogeneity caused by the varied duration and dosage of kefir beverage treatment, a random effects model was used to estimate the pooled WMD. Findings indicated a more significant reduction in the FBS (WMD = -10.28; 95% CI: -16.53-4.02; P = 0.001) and insulin (WMD = -2.87; 95% CI: -3.96-1.78; P < 0.00001) in the kefir treatment group. Furthermore, kefir consumption could reduce HbA1c (HbA1c = -0.64 -1.36, 0.08), while this effect was not considered significant (-0.64; 95% CI: -1.36-0.08; P = 0.08). The results of our meta-analysis indicated that kefir beverage could reduce the FBS and insulin levels without a significant effect on HbA1c. In general, our findings showed that kefir beverages may have beneficial effects on glycemic control. However, more clinical data and research into the mechanism of probiotics are required to clarify the beneficial effects of probiotics on glycemic markers.

The effect of apple vinegar consumption on glycemic indices, blood pressure, oxidative stress, and homocysteine in patients with type 2 diabetes and dyslipidemia: A randomized controlled clinical trial.

BACKGROUND: Some foods and drinks contain special ingredients, causing impressive effects on human health. The aim of the current study was to assess the health effects of apple vinegar in patients with diabetes and dyslipidemia. METHOD: Seventy participants with type 2 diabetes and hyperlipidemia were randomly assigned into an intervention and control group in order to assess the effect of 20 ml apple vinegar per day using an 8-week parallel study. Fasting blood sugar (FBS), homeostasis model assessment for insulin resistance (HOMA-IR), homeostasis model assessment for b-cell function (HOMA-B), quantitative insulin sensitivity checks index (QUICKI), insulin, malondialdehyde (MDA), 2,20-Diphenyl-1- picrylhydrazyl (DPPH), homocysteine, systolic blood pressure (SBP), and diastolic blood pressure (DBP) were measured at the beginning and end of the study. RESULTS: The intervention with apple vinegar could significantly improve FBS (mean change: -10.16 ± 19.48 mg/dl, p = 0.006) and DPPH (mean change: 16.58 ± 11.56, p < 0.001) within intervention group and in comparison with control group (p < 0.001). Additionally, the significant increase of MDA in control group (p < 0.05) caused a considerable difference between two groups. Glycemic indices containing insulin, HOMA-IR, HOMA-B, and QUICKI decrease significantly in both groups (p < 0.05). No considerable effect was observed on blood pressure and homocysteine in intervention group as well as control group. CONCLUSION: This trial provided some evidences that apple vinegar consumption may cause beneficial effects on glycemic indices and oxidative stress in individuals with diabetes and dyslipidemia. This randomized clinical trial was registered in the Iranian Registry of Clinical Trials (https://www.irct.ir/) as 2013070710826N5.

The effect of vitamin D supplementation on the androgenic profile in men: A systematic review and meta-analysis of clinical trials.

The aim of this systematic review and meta-analysis was to evaluate the effect of vitamin D supplementation on total testosterone (TT) and sex hormone-binding globulin (SHBG) in men. We searched PubMed, Scopus and Web of Science for randomized, controlled trials of vitamin D supplementation in men ≥18 years old up to September 2018, without language restrictions. Meta-analysis was based on a random effects model. The systematic review was registered as CRD42018094498. We identified 3,402 articles, of which eight studies with 10 effect sizes met the inclusion criteria. Vitamin D daily dose equivalents ranged from 600 to 4,000 per day to 60,000 IU per week; duration was 6 weeks to 36 months. In general, vitamin D supplementation had no significant effect on TT (MD = 0.20, 95% CI: -0.20, 0.60, p = 0.336) and SHBG (MD = 1.56, 95% CI: -0.85, 3.97, p = 0.204). Subgroup analysis conducted with duration of prescription, type (daily or weekly), dosing frequency and baseline vitamin D and TT concentration showed that vitamin D did not significantly affect TT. The present study did not find any evidence to support beneficial effect of vitamin D supplementation on TT and SHBG in men. Thus, further large-scale randomised controlled trials are required to evaluate the effects of vitamin D supplementation on androgen in men.

The clinical effects of purslane (Portulaca oleracea) seeds on metabolic profiles in patients with nonalcoholic fatty liver disease: A randomized controlled clinical trial.

Nonalcoholic fatty liver disease (NAFLD) is the most common form of chronic liver diseases associated with unfavorable metabolic profiles and oxidative stress parameters. This study was designed to determine the effects of purslane seeds consumption with a low-calorie diet on insulin resistance, lipid profile, and oxidative stress indices in patients with NAFLD. This randomized controlled clinical trial was conducted on 54 individuals with NAFLD. Subjects were randomly assigned to consume either 10 g/day of purslane seeds sachet before breakfast and dinner in addition to a low-calorie diet (n = 27) or only the low-calorie diet (n = 27) for 8 weeks. Fasting blood samples were collected at the beginning and end of the study to measure relevant variables. Intake of purslane seeds with the low-calorie diet led to a significant decrease in serum concentrations of fasting blood sugar (FBS; -3.52 ± 10.45 compared with 3.03 ± 9.01 mg/dl, P = 0.017), quantitative insulin sensitivity check index (QUICKI; 0.13 ± 0.27 compared with -0.002 ± 0.016, P = 0.017), total cholesterol (4.33 ± 34.04 compared with 23.48 ± 29.47 mg/dl, P = 0.032), and low-density lipoprotein cholesterol (LDL-C; -4.35 ± 22.65 compared with 11.82 ± 16.08 mg/dl, P = 0.004) after intervention. Compared with the control group, purslane seeds consumption with adherence to a low-calorie diet had beneficial effects on FBS, HOMA-IR, QUICKI, serum total, and LDL-C in patients with NAFLD but did not affect other glycemic, lipid profile, and oxidative stress parameters.

Does pomegranate consumption affect weight and body composition? A systematic review and meta-analysis of randomized controlled clinical trials.

Pomegranate is rich in tannins, polyphenols, flavonoids, and several other types of antioxidant compounds whose role in weight loss has been shown in previous studies. However, the results have been mixed regarding the effects of pomegranate consumption on weight loss. Electronic databases such as PubMed, Scopus, ISI Web of Science, and Google Scholar were systematically searched up to May 2018 for controlled clinical trials assessing the effect of pomegranate consumption on weight loss. 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. Thirteen randomized controlled trials (including 513 participants) were included in the present meta-analysis. Compared with the control groups, there was no significant reduction in bodyweight, body mass index, waist circumference, and body fat percentage after pomegranate consumption (WMD = -0.23 kg, 95% CI: -0.94, 0.47, P = 0.515; WMD = -0.12 kg/m2 , 95% CI: -0.29, 0.03, P = 0.132; WMD = -0.08 cm, 95% CI: -0.33, 0.17, P = 0.534; WMD = -0.05, 95% CI: -1.66, 1.55, P = 0.947, respectively). According to the results of the present systematic review and meta-analysis, there was no significant effect of pomegranate consumption on weight and body composition indices.