Peppermint and menthol: a review on their biochemistry, pharmacological activities, clinical applications, and safety considerations.

In this manuscript, we conducted a comprehensive review of the diverse effects of peppermint on human health and explored the potential underlying mechanisms. Peppermint contains three main groups of phytochemical constituents, including essential oils (mainly menthol), flavonoids (such as hesperidin, eriodictyol, naringenin, quercetin, myricetin, and kaempferol), and nonflavonoid phenolcarboxylic acids. Peppermint exhibits antimicrobial, antioxidant, anti-inflammatory, immunomodulatory, anti-cancer, anti-aging, and analgesic properties and may be effective in treating various disorders, including gastrointestinal disorders (e.g., irritable bowel syndrome, dyspepsia, constipation, functional gastrointestinal disorders, nausea/vomiting, and gallbladder stones). In addition, peppermint has therapeutic benefits for psychological and cognitive health, dental health, urinary retention, skin and wound healing, as well as anti-depressant and anti-anxiety effects, and it may improve memory. However, peppermint has paradoxical effects on sleep quality and alertness, as it has been shown to improve sleep quality in patients with fatigue and anxiety, while also increasing alertness under conditions of monotonous work and relaxation. We also discuss its protective effects against toxic agents at recommended doses, as well as its safety and potential toxicity. Overall, this review provides the latest findings and insights into the properties and clinical effects of peppermint/menthol and highlights its potential as a natural therapeutic agent for various health conditions.

Oxymel: A systematic review of preclinical and clinical studies.

Background: Oxymel is a functional beverage with a rich historical background of use in multiple societies. Various simple and compound oxymels are prescribed in certain complementary and traditional medical systems, including traditional Persian Medicine. In recent years, numerous clinical and preclinical studies have been conducted in the pharmacy and food industry to investigate the efficacy of various oxymel formulations. This article aims to systematically review and summarize interventional studies on oxymel in both clinical research and animal models. Methods: Relevant articles were searched in Embase, MEDLINE, Web of Science Core Collection, Scopus, and Google Scholar from inception to July 2023 using the keyword "Oxymel" and its equivalents in other languages. Animal and human interventional studies were selected from the search results for review. Results: This review includes twenty studies, comprising twelve clinical trials, two case studies, and six animal studies. The most commonly reported actions of oxymel include positive effects on the cardiovascular system, as well as antioxidant and anti-inflammatory properties. Furthermore, compound oxymel formulations have demonstrated additional benefits depending on the inclusion of specific medicinal herbs. Conclusion: Based on our findings, oxymel appears to be a valuable functional food for healthy individuals and a potentially effective and safe treatment option for managing certain diseases such as asthma, obesity, and type 2 diabetes. However, further clinical trials with larger sample sizes and longer durations are needed to fully elucidate the potential side effects and benefits of both simple and compound oxymels in various disease states.

Comparison of nutritional supplements for glycemic control in type 2 diabetes: A systematic review and network meta-analysis of randomized trials.

AIMS: Direct and indirect evidence were combined in this systematic-review and network meta-analysis (NMA) to assess and compare the effect of nutritional supplements on glycemic control, and rank the supplements accordingly. METHODS: PubMed, Scopus, and Web of Science were searched up to April 2021. We included randomized controlled trials that investigated the effect of vitamins D, C, and E, magnesium, zinc, calcium, selenium, and omega-3 on at least one glycemic marker, including glycated hemoglobin (HbA1c), fasting blood sugar (FBS), homeostasis model assessment-estimated insulin resistance (HOMA-IR), HOMA-B, and insulin, in adults with type 2 diabetes. To estimate effectiveness of supplements, a random-effects NMA in the Bayesian framework was applied. To assess risk of bias, Cochrane Collaboration Tool was used. RESULTS: Analysis of 178 studies indicated that zinc, vitamin D, omega-3, vitamin C, and vitamin E were effective in reducing HbA1c with low certainty. For reduction of FBS, zinc, vitamin D, and vitamin C, and for HOMA-IR, vitamin D were effective with low certainty. None of the supplements were effective in the reduction of insulin and HOMA-B with low certainty. After excluding poor-quality studies, only vitamin D was significantly effective in reducing all of the markers. Consistently, when the analysis was restricted to studies with a duration of ≥12-weeks, vitamin D reduced HbA1c, FBS, and HOMA-IR. CONCLUSIONS: Vitamin D supplementation was more effective compared to other supplements in improving HbA1c, FBS, and HOMA-IR, albeit with low certainty of evidence. This result was confirmed by low-risk of bias studies. REGISTRATION: CRD42021240691.

Effect of Artemisia extract on glycemic control: A systematic review and meta-analysis of randomized controlled trial.

BACKGROUND AND AIM: Animal and human studies have indicated anti-diabetic effect of Asteraceae. The present study aimed to systematically review and analyse randomized controlled trials assessing the effect of Artemisia extract on glycemic status in patients with impaired glycemic control. METHODS: Web of Science, Cochrane library, EMBASE and PubMed databases were searched from the earliest possible date up to 7th October 2020. RESULTS: Six studies were included in the meta-analysis. Analysis showed that supplementation with Artemisia extract decreased homeostatic model assessment of insulin resistance (HOMA-IR) (-0.734, 95% CI: -1.236 to -0.232, P = .019) in comparison to placebo. However, reductions in fasting blood glucose (FBG) (-0.595, 95% CI: -1.566 to 0.376, P = .164), insulin (-0.322, 95% CI: -1.047 to 0.404, P = .286) and glycated haemoglobin (-0.106, 95% CI: -0.840 to 0.629, P = .678) were not statistically significant. CONCLUSION: Supplementation with Artemisia extract may reduce HOMA-IR, but beneficial effects on other markers such as FBG requires further investigations.

The effect of cinnamon supplementation on lipid profiles in patients with type 2 diabetes: A systematic review and meta-analysis of clinical trials.

OBJECTIVE: The present systematic review and meta-analysis was performed to evaluate the effect of cinnamon supplementation on blood lipid profiles in patients with type 2 diabetes. METHODS: A systematic search (with no language restrictions) was performed in PubMed, Embase, Scopus, Web of Science, and Cochrane Library to identify relevant clinical trials up to 8th March 2020. Weighted mean differences (WMDs) and 95 % confidence intervals (CI) were pooled based on the random-effects model. Heterogeneity, publication bias, and sensitivity analyses were performed based on standard methods. RESULTS: Sixteen studies, involving 1025 participants, were included in the meta-analysis. This study found a significant decrease in triglycerides (TG) (WMD: -26.27 mg/dl, 95 % CI: [-38.93, -13.61], P < 0.001), total cholesterol (TC) (WMD: -13.93 mg/dl, 95 % CI: [-25.64, -2.22], P = 0.020), and low-density lipoprotein cholesterol (LDL-C) levels (WMD: -6.13 mg/dl, 95 % CI: [-10.72, -1.53], P = 0.009), while no change was observed on high-density lipoprotein cholesterol (HDL) concentration (WMD: 0.64 mg/dl, 95 % CI: [-0.18, 1.46], P = 0.128), in patients with type 2 diabetes. The reduction in TG, TC, and LDL-C was greater in; Eastern compared to Western countries, and studies with a duration of < 2 compared to ≥ 2 months. The increase in HDL was greater in; participants with a BMI ≥ 30 compared to <30, Western compared to Eastern countries, and intervention durations of ≥ 2 compared to < 2 months. CONCLUSIONS: Cinnamon supplementation significantly decreased serum TG, TC, and LDL-C concentrations, but did not change HDL-C levels, in patients with type 2 diabetes.

Effects of green tea or green tea catechin on liver enzymes in healthy individuals and people with nonalcoholic fatty liver disease: A systematic review and meta-analysis of randomized clinical trials.

The therapeutic potential of green tea as a rich source of antioxidants and anti-inflammatory compounds has been investigated by several studies. The present study aimed to systematically review and analyze randomized clinical trials (RCTs) assessing the effects of green tea, catechin, and other forms of green tea supplementation on levels of liver enzymes. PubMed, SCOPUS, EMBASE, and Cochrane databases were searched until February 2019. All RCTs investigating the effect of green tea or its catechin on liver enzymes including alanine transaminase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and bilirubin were included. A total of 15 RCTs were included. The overall effect of green tea on liver enzymes was nonsignificant (ALT [Standardized mean difference (SMD)= -0.17, CI -0.42 to 0.08, p = .19], AST [SMD = -0.07, CI -0.43 to 0.29, p = .69], and ALP [SMD = -0.17, CI -0.45 to 0.1, p = .22]). However, subgroup analyses showed that green tea reduced the levels of liver enzymes in participants with nonalcoholic fatty liver disease (NAFLD) but in healthy subjects, a small significant increase in liver enzymes was observed. In conclusion, the results of this study suggest that the effect of green tea on liver enzymes is dependent on the health status of individuals. While a moderate reducing effect was observed in patients with NAFLD, in healthy subjects, a small increasing effect was found.

Effect of probiotic and synbiotic supplementation on inflammatory markers in health and disease status: A systematic review and meta-analysis of clinical trials.

The current systematic review and meta-analysis investigated the effect of probiotic/synbiotic on a wide range of inflammatory and anti-inflammatory markers in healthy and various disease conditions. PubMed, SCOPUS and Web of Science databases were searched. All clinical trials which investigated the effect of oral administration of probiotic or synbiotic on inflammatory markers (C-reactive protein (CRP), interleukin (IL) 1ß, IL-4, IL-6, IL-8, IL-10, IL-12, tumor necrosis factor (TNF) α, interferon (IFN) γ and transforming growth factor (TGF) ß) for more than one week with concurrent control groups were included. One-hundred sixty seven publications was analysed. Results were as follows: CRP decreased in healthy, metabolic disorders, inflammatory bowel disease (IBD), arthritis and critically ill condition but not in renal failure. IL-1B: no change in healthy subjects and arthritis. TNF-α: decreased in healthy, fatty liver, IBD and hepatic cirrhosis, no change in diabetes, metabolic syndrome (MS) + PCOS (polycystic ovary syndrome) and arthritis. IL-6: no change in healthy, metabolic disorders and arthritis, increased in cirrhosis and renal failure, decreased in PCOS + MS. IL-10: no change in healthy, IBD and metabolic disorders, increased in arthritis. IL-4, IL-8, IL-12, IFN-g and TGF-b: no change in healthy subjects. In conclusion, probiotic/synbiotic decreased some of the inflammatory markers. The intervention was most effective in CRP and TNF-α reduction in healthy or disease state. Moreover, the intervention decreased inflammation most effectively in the following disease conditions, respectively: IBD, arthritis, fatty liver. PROSPERO REGISTRATION NUMBER: CRD42018088688.

Effect of Probiotic Supplementation on CD4 Cell Count in HIV-Infected Patients: A Systematic Review and Meta-analysis.

Progressive decline in CD4 cell counts is associated with human immunodeficiency virus (HIV) disease progression. Loss of CD4 cells might contribute to gut microbiota alteration and bacterial translocation. Probiotics, by inducing epithelial healing, may promote the restoration of the intestinal CD4+ T-cell population. The aim of this meta-analysis was to systematically review all randomized controlled trials (RCTs) of probiotic/prebiotic/synbiotic supplementation on CD4 cell counts in HIV-infected patients. A systematic search of RCTs was conducted through PubMed, Scopus, and Google Scholar databases up to August 2015. Effect sizes of eligible studies were pooled using random-effects models (the DerSimonian-Laird estimator). Eleven studies with 14 treatment arms met the inclusion criteria. Pooled analysis showed no significant reduction in CD4 counts (-7.5 mg/l, p = .7) in intervention-treated individuals. Subgroup analysis on potential influencing factors highlighted sex, country of origin, study duration, and the type of intervention as having significant effects on CD4 cell counts. As a whole, the results of this meta-analysis suggested that supplementation with probiotic may not change CD4 counts. However, a significant increase in CD4 counts was seen in females and following synbiotics as opposed to treatment with pro- or prebiotics alone.