The effects of green tea extract supplementation on body composition, obesity-related hormones and oxidative stress markers: a grade-assessed systematic review and dose-response meta-analysis of randomised controlled trials

Research indicates that green tea extract (GTE) supplementation is beneficial for a range of conditions, including several forms of cancer, CVD and liver diseases; nevertheless, the existing evidence addressing its effects on body composition, oxidative stress and obesity-related hormones is inconclusive. This systematic review and meta-analysis aimed to investigate the effects of GTE supplementation on body composition (body mass (BM), body fat percentage (BFP), fat mass (FM), BMI, waist circumference (WC)), obesity-related hormones (leptin, adiponectin and ghrelin) and oxidative stress (malondialdehyde (MDA) and total antioxidant capacity (TAC)) markers. We searched proper databases, including PubMed/Medline, Scopus and Web of Science, up to July 2022 to recognise published randomised controlled trials (RCT) that investigated the effects of GTE supplementation on the markers mentioned above. A random effects model was used to carry out a meta-analysis. The heterogeneity among the studies was assessed using the I2 index. Among the initial 11 286 studies identified from an electronic database search, fifty-nine studies involving 3802 participants were eligible to be included in this meta-analysis. Pooled effect sizes indicated that BM, BFP, BMI and MDA significantly reduced following GTE supplementation. In addition, GTE supplementation increased adiponectin and TAC, with no effects on FM, leptin and ghrelin. Certainty of evidence across outcomes ranged from low to high. Our results suggest that GTE supplementation can attenuate oxidative stress, BM, BMI and BFP, which are thought to negatively affect human health. Moreover, GTE as a nutraceutical dietary supplement can increase TAC and adiponectin.

The effects of guar gum supplementation on lipid profile in adults: a GRADE-assessed systematic review, meta-regression and dose-response meta-analysis of randomised placebo-controlled trials

Recent meta-analytic work indicated that guar gum supplementation might improve lipid profile markers in different populations. However, critical methodological limitations such as the use of some unreliable data and the lack of inclusion of several relevant studies, and the scarcity in assessments of regression and dose-specific effects make it difficult to draw meaningful conclusions from the meta-analysis. Therefore, current evidence regarding the effects of guar gum supplementation on lipid profile remains unclear. The present systematic review, meta-regression and dose-response meta-analysis aimed to examine the effects of guar gum supplementation on lipid profile (total cholesterol (TC), LDL, TAG and HDL) in adults. Relevant studies were obtained by searching the PubMed, SCOPUS, Embase and Web of Science databases (from inception to September 2021). Weighted mean differences (WMD) and 95 % CI were estimated via a random-effects model. Heterogeneity, sensitivity analysis and publication bias were reported using standard methods. Pooled analysis of nineteen randomised controlled trials (RCT) revealed that guar gum supplementation led to significant reductions in TC (WMD: -19·34 mg/dl, 95 % CI -26·18, -12·49, P < 0·001) and LDL (WMD: -16·19 mg/dl, 95 % CI -25·54, -6·83, P = 0·001). However, there was no effect on TAG and HDL among adults in comparison with control group. Our outcomes suggest that guar gum supplementation lowers TC and LDL in adults. Future large RCT on various populations are needed to show further beneficial effects of guar gum supplementation on lipid profile and establish guidelines for clinical practice.

An update and systematic review on the treatment of primary dysmenorrhea

OBJECTIVES

Primary dysmenorrhea is a painful uterine contraction caused by endometrial laceration. Drug therapies and complementary medicine have been used to treat dysmenorrhea. The aim of this study was to investigate and offer an updated perspective on the treatments for dysmenorrhea.

METHODS

The present study was conducted in accordance with the PRISMA checklist for systematic reviews and meta-analyses. The required information was collected based on searches for the following keywords: treatment, primary dysmenorrhea, medicinal plants, chemical drugs, and herbs. Searches were performed on databases Pubmed, Web of Sciences, Scopus, Iran medex, and SID by March 2018 to find literature in the English and Persian languages on this subject without a time limit.

RESULTS

This review included 17 papers, 10 of which on complementary medicine, three on drug therapies, and four on acupuncture and acupressure. The largest and smallest samples had 303 and 24 patients, respectively. Length of treatment ranged from one to six months and the measures most commonly used in the studies were the visual analogue scale and clinical efficacy. Reported complications included gastrointestinal events, nausea, vomiting, diarrhea, abdominal pain, and liver and kidney disorders.

CONCLUSION

Medicinal plants, drugs, and acupressure seem to suppress pain by reducing the level of prostaglandins, mediating nitric oxide, increasing beta-endorphin levels, blocking the calcium channel, and enhancing circulatory flow through the uterine pathway. Further trials are required to confirm the benefits of the procedures described and ensure the absence of complications.

Investigating the effects of Capparis Spinosa on hepatic gluconeogenesis and lipid content in streptozotocin-induced diabetic rats

The present study aimed to investigate the effects of administration of Capparis spinosa (CS) fruit aqueous extract on liver metabolism in streptozotocin (STZ)-induced diabetic rats. The aqueous extract of CS was orally administered at a dose of 20mg/kg for 28 consecutive days and then its effects on blood glucose, lipid and insulin levels in normal and STZ diabetic rats were comparatively investigated. Furthermore, the effects of CS on the activity and expression of the key enzymes of gluconeogenesis and hepatic lipid content were investigated. The results showed that administration of CS extract in the STZ diabetic rats significantly decreased blood glucose level, while no significant influence on the insulin level. In addition, CS significantly decreased blood and liver triglyceride and cholesterol content in STZ diabetic rats. Furthermore, CS administration significantly reduced the mRNA expression and enzyme activities of glucose-6- phosphatase and phosphoenolpyruvate carboxykinase in liver tissues. Our findings demonstrated the beneficial effects of CS on blood glucose and lipid levels in an insulin- independent manner. This study also showed that CS improved the circulating levels of triglyceride and cholesterol. In addition, direct inhibition of gluconeogenesis in liver may be a probable mechanism of action of this plant. Since CS also decreased liver lipid content, we suggest that CS administration might be a beneficial therapeutic approach for metabolic syndrome and fatty liver.