Promising experimental studies suggest that quercetin has potential anti-inflammatory effects. However, the results of current clinical trials on quercetin's effects on the C-reactive protein (CRP), a sensitive inflammatory biomarker, are ambiguous. We conducted a meta-analysis of available randomized controlled trials (RCTs) to resolve this inconsistency and quantify the net effect of quercetin on circulating CRP concentrations. A systematic search was performed in several databases including SCOPUS, PubMed-Medline and Google Scholar until 16 June 2016. We used a random-effects model in combination with weight mean difference (WMD) and 95% confidence intervals (CI) for data analysis. Standard methods were used for the assessment of heterogeneity, meta-regression, sensitivity analysis and publication bias. The meta-analysis of seven RCTs (10 treatment arms) showed a significant reduction of circulating CRP levels (WMD: -0.33 mg/l; 95% CI: -0.50 to -0.15; P<0.001) following quercetin supplementation. In the subgroup analysis, a significant reducing effect was observed in trials with ⩾500 mg/day dosage (WMD: -0.34 mg/l; 95% CI: -0.52, -0.16; P⩽0.001) and in those with CRP <3 mg/l (WMD: -0.34 mg/l; 95% CI: -0.51, -0.18; P⩽0.001). In meta-regression, there was no association between changes in CRP concentrations, dose of supplementation and CRP baseline values. Our findings showed a significant effect of quercetin supplementation on the C-reactive protein-especially at doses above 500 mg/day and in patients with CRP <3 mg/l.
Background: Polycystic ovary syndrome (PCOS) is a common endocrine disorder. The aim of the present study was to evaluate the effects of the oral administration of thylakoid-rich spinach extract and the caraway aqueous extract in letrozole-induced polycystic ovary syndrome rats. Methods: Sixty female Sprague-Dawley rats were randomly divided into five groups of 12 animals each. Letrozole (1 mg/kg) was administered orally for a period of 28 days to induce PCOS. Sham and PCOS control rats received 1 mL/day of distilled water, and the three groups of PCOS rats were given 150 mg/kg of metformin, 3 g/kg of caraway, and thylakoid at a dose of 6 mg chlorophyll/gr food intake/day by oral gavage for 8 weeks. Finally, blood samples were collected and the right ovary of rats was removed, weighed, and fixed in 4% buffered formalin to determine the biochemical and stereological parameters. Results: Compared to the PCOS control group, consuming metformin, thylakoid, and caraway extracts significantly improved the fasting blood sugar (FBS), tumor necrosis factor-alpha (TNF-α), malondialdehyde (MDA), luteinizing hormone (LH), insulin resistance, and body weight, increased the volume of the corpus luteum, and reduced the number of atretic follicles after 8 weeks (< 0.05). Although caraway treatment caused a significant increase in the HDL-C (High-density lipoprotein cholesterol) level (P < 0.001), no significant change was observed in terms of HDL-C in the thylakoid and metformin groups compared to the PCOS control group. Conclusion: Our data showed that the consumption of thylakoid and caraway extracts for 8 weeks may have beneficial effects on the biochemical and stereological factors in PCOS-induced rats.
Background: Diabetes mellitus as one of the prevalent endocrine disease is associated with a high burden of oxidative stress due to the overproduction of reactive oxygen species (ROS), which may lead to decreased antioxidant defense system, increased risk of inflammation, neuropathy, nephropathy, and cardiovascular disease. All of these may, in turn, cause a reduced quality of life in these patients. Objectives: This study aimed to evaluate the effect of vitamin E and vitamin C on the quality of life in patients with type 2 diabetes. Methods: Forty-five patients with type 2 diabetes were randomly divided into three groups to receive vitamin E (400 IU day-1), vitamin C (1000 mg day-1), and placebo for six weeks. Before and after the intervention, the quality of life was assessed with a valid Persian version of SF-36 (short-form health Survey-36) questionnaire. Results: Supplementation with vitamin E and vitamin C were associated with significant improvements in the role limitations due to physical health (P = 0.02) and general health (P = 0.05). Furthermore, there were significant increases in the role limitations due to physical health, role limitations due to emotional problems, social functioning, and general health in the vitamin E group. Also, a significant increase was observed in general health score in the vitamin C group. Conclusions: This study indicates that short-term supplementation of vitamin E and vitamin C may improve the quality of life in patients with type 2 diabetes through alleviating oxidative stress.
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