The effects of grape seed extract on glycemic control,serum lipoproteins,inflammation, and body weight: A systematic review and meta‐analysis of randomized controlled trials

The aim of this systematic review and meta‐analysis was to analyze the effects of grape seed extract (GSE) on glycemic control and serum lipoproteins, inflammation and body weight. Two independent authors systematically searched online databases including EMBASE, Scopus, PubMed, Cochrane Library, and Web of Science from inception until May 30, 2019. Cochrane Collaboration risk of bias tool was applied to assess the methodological quality of included trials. The heterogeneity among the included studies was assessed using Cochrane's Q test and I‐square (I²) statistic. Data were pooled using a random‐effects model and weighted mean difference (WMD) was considered as the overall effect size. Fifty trials were included in this meta‐analysis. Pooling effect sizes from studies demonstrated a significant decrease in fasting plasma glucose (FPG) (WMD): ?2.01; 95% confidence interval (CI): ?3.14, ?0.86), total cholesterol (TC; WMD: ?6.03; 95% CI: ?9.71, ?2.35), low‐density lipoprotein (LDL) cholesterol (WMD: ?4.97; 95% CI: ?8.37, ?1.57), triglycerides (WMD: ?6.55; 95% CI: ?9.28, ?3.83), and C‐reactive protein (CRP) concentrations (WMD: ?0.81; 95% CI: ?1.25, ?0.38) following GSE therapy. Grape seed did not influence HbA1c, HDL cholesterol levels, and anthropometric measurements. This meta‐analysis demonstrated that GSE intake significantly reduced FPG, TC, LDL cholesterol, triglycerides, and CRP levels.     

The effects of melatonin on signaling pathways and molecules involved in glioma

Glioblastoma is one of the most common brain tumors with high invasion and malignancy. Despite extensive research in this area and the use of new and advanced therapies, the survival rate in this disease is very low. In addition, resistance to treatment has also been observed in this disease. One of the reasons for rapid progression and failure in treatment for this disease is the presence of a class of cells with high proliferation and high differentiation, a class called glioblastoma stem-like cells shown as being the source of glioblastoma tumors. It has been reported that several oncogenes are expressed in this disease. One important issue in recognizing the pathogenesis of this disease, and which could improve the treatment process, is the identification of involved oncogenes as well as molecules that affect the reduction of the expression of these oncogenes. Melatonin regulates the biological rhythm and inhibits the proliferation of malignant glioma cells due to antioxidant and anti-apoptotic effects. Melatonin has been considered in biological processes and in signaling pathways involved in the development of glioma. The aim of this review is to investigate the effects of melatonin on signaling pathways and molecules involved in the progression of glioma.     

The effects of vitamin D treatment on glycemic control,serum lipid profiles,and C-reactive protein in patients with chronic kidney disease: a systematic review and meta-analysis of randomized controlled trials

Purpose

Insulin resistance, dyslipidemia and increased systemic inflammation are important risk factors for chronic kidney disease (CKD). Hence, vitamin D administration might be an appropriate approach to decrease the complications of CKD. Randomized controlled trials assessing the effects of vitamin D supplementation or treatment on glycemic control, lipid profiles, and C-reactive protein (CRP) among patients with CKD were included.

Methods

Two independent authors systematically searched online databases including EMBASE, Scopus, PubMed, Cochrane Library, and Web of Science in November 2018 with no time restriction. Cochrane Collaboration risk of bias tool was applied to assess the methodological quality of included trials. Between-study heterogeneity was estimated using the Cochran’s Q test and I-square (I²) statistic. Data were pooled using a random-effects model and weighted mean difference (WMD) was considered as the overall effect size.

Results

Of the 1358 citations identified from searches, 17 full-text articles were reviewed. Pooling findings from five studies revealed a significant reduction in fasting glucose (WMD:???18.87; 95% CI:???23.16,???14.58) and in homeostatic model assessment of insulin resistance (HOMA-IR) through three studies (WMD:???2.30; 95% CI:???2.88,???1.72) following the administration of vitamin D. In addition, pooled analysis revealed a significant reduction in triglycerides (WMD:???32.52; 95% CI:???57.57,???7.47) through six studies and in cholesterol concentrations (WMD:???7.93; 95% CI:???13.03,???2.83) through five studies, following vitamin D supplementation or treatment, while there was no effect on insulin, HbA1c, LDL and HDL cholesterol, and CRP levels.

Conclusions

This meta-analysis demonstrated the beneficial effects of vitamin D supplementation or treatment on improving fasting glucose, HOMA-IR, triglycerides and cholesterol levels among patients with CKD, though it did not influence insulin, HbA1c, LDL and HDL cholesterol, and CRP levels.

     

Effects of quercetin supplementation on glycemic control among patients with metabolic syndrome and related disorders: A systematic review and meta‐analysis of randomized controlled trials

This systematic review and meta‐analysis of randomized controlled trials was performed to determine the effect of quercetin supplementation on glycemic control among patients with metabolic syndrome and related disorders. Databases including PubMed, MEDLINE, EMBASE, Web of Science, and Cochrane Central Register of Controlled Trials were searched until August 30, 2018. Nine studies with 10 effect sizes out of 357 selected reports were identified eligible to be included in current meta‐analysis. The pooled findings indicated that quercetin supplementation did not affect fasting plasma glucose (FPG), homeostasis model of assessment‐estimated insulin resistance, and hemoglobin A1c levels. In subgroup analysis, quercetin supplementation significantly reduced FPG in studies with a duration of ≥8 weeks (weighted mean difference [WMD]: ?0.94; 95% confidence interval [CI; ?1.81, ?0.07]) and used quercetin in dosages of ≥500 mg/day (WMD: ?1.08; 95% CI [?2.08, ?0.07]). In addition, subgroup analysis revealed a significant reduction in insulin concentrations following supplementation with quercetin in studies that enrolled individuals aged <45 years (WMD: ?1.36; 95% CI [?1.76, ?0.97]) and that used quercetin in dosages of ≥500 mg/day (WMD: ?1.57; 95% CI [?1.98, ?1.16]). In summary, subgroup analysis based on duration of ≥8 weeks and used quercetin in dosages of ≥500 mg/day significantly reduced FPG levels.     

A comparison between the effects of flaxseed oil and fish oil supplementation on cardiovascular health in type 2 diabetic patients with coronary heart disease: A randomized,double‐blinded,placebo‐controlled trial

This study compared the effects of flaxseed and fish oil supplementation on cardiovascular risk parameters in diabetic patients with coronary heart disease. Participants were randomly allocated into three intervention groups to receive either 1,000 mg of omega‐3 fatty acids from fish oil or 1,000 mg of omega‐3 fatty acids from flaxseed oil or placebo (n = 30 each group) twice a day for 12 weeks. A significant reduction in insulin levels (.04) was observed following flaxseed oil and fish oil supplementation compared with the placebo. In addition, a significant reduction in high‐sensitivity C‐reactive protein (.02) was seen after flaxseed oil supplementation compared with the placebo and a significant increase in total nitrite (.001) was seen after flaxseed oil and fish oil intake compared with placebo. Additionally, a significant increase in total antioxidant capacity (p < .001) after consuming flaxseed oil and fish oil compared with placebo and glutathione levels (.001) after consuming fish oil compared with flaxseed oil and placebo was observed. Overall, our study revealed the beneficial effects of flaxseed oil and fish oil supplementation on few metabolic profiles. This study suggests that the effect of flaxseed oil in reducing insulin and increasing total nitrite and total antioxidant capacity is similar to fish oil.