Comparative studies on the hypolipidemic, antioxidant and hepatoprotective activities of catechin-enriched green and oolong tea in a double-blind clinical trial

Effects of green tea on lipid profile in overweight and obese women

The effect of green tea administration on serum lipids' concentrations remains unclear as various investigations, which have explored this topic, have produced conflicting results. Gender might be one of the factors influencing the impact of green tea on the lipid profile. Hence, we conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to assess the effect of green tea intake on the lipid profile in overweight and obese women. We searched five databases (Web of Science, SCOPUS, Embase, PubMed/Medline, and Google Scholar) using a combination of MeSH and non-MeSH terms. Results were expressed as weighted mean differences (WMDs) and 95% confidence intervals (CIs) and synthesized with a random-effects model. In total, 15 eligible RCTs with 16 arms (1818 participants) were included in the meta-analysis. The combined effect size revealed a significant reduction in total cholesterol (TC) (WMD: -4.45 mg/dl, 95% CI: -6.63, -2.27, P<0.001) and low-density lipoprotein cholesterol (LDL-C) (WMD: -4.49 mg/dl, 95% CI: -7.50 to -1.47, P=0.003) concentrations following green tea supplementation in overweight and/or obese women. In addition, a more pronounced reduction of triglyceride (TG) levels occurred when the baseline TG value was ≥150 mg/dL (WMD: -24.45 mg/dL, 95% CI: -40.63 to -8.26, P=0.003). Moreover, a significant decrease in TG concentrations occurred in RCTs conducted on overweight subjects (BMI: 25-29.99 kg/m2) (WMD: -5.88 mg/dl, 95% CI: -10.76 to -0.99, P=0.01). In the subgroup analyses based on the study population, a notable increase in high-density lipoprotein cholesterol (HDL-C) values was observed in obese individuals (>30 kg/m2) (WMD: 2.63 mg/dl, 95% CI: 0.10 to 5.16, P=0.041). Consumption of green tea causes a reduction in LDL-C and TC concentrations in overweight and obese women. The decline in TG levels was notable particularly in overweight patients with hypertriglyceridemia at baseline. In addition, a significant increase in HDL-C was detected in obese subjects following intake of green tea.

Separation and Detection of Catechins and Epicatechins in Shanxi Aged Vinegar Using Solid-Phase Extraction and Hydrophobic Deep Eutectic Solvents Combined with HPLC

This research presents a new, eco-friendly, and swift method combining solid-phase extraction and hydrophobic deep eutectic solvents (DES) with high-performance liquid chromatography (SPE-DES-HPLC) for extracting and quantifying catechin and epicatechin in Shanxi aged vinegar (SAV). The parameters, such as the elution solvent type, the XAD-2 macroporous resin dosage, the DES ratio, the DES volume, the adsorption time, and the desorption time, were optimized via a one-way experiment. A central composite design using the Box-Behnken methodology was employed to investigate the effects of various factors, including 17 experimental runs and the construction of three-dimensional response surface plots to identify the optimal conditions. The results show that the optimal conditions were an HDES (tetraethylammonium chloride and octanoic acid) ratio of 1:3, an XAD-2 macroporous resin dosage of 188 mg, and an adsorption time of 11 min. Under these optimal conditions, the coefficients of determination of the method were greater than or equal to 0.9917, the precision was less than 5%, and the recoveries ranged from 98.8% to 118.8%. The environmentally friendly nature of the analytical process and sample preparation was assessed via the Analytical Eco-Scale and AGREE, demonstrating that this method is a practical and eco-friendly alternative to conventional determination techniques. In summary, this innovative approach offers a solid foundation for the assessment of flavanol compounds present in SAV samples.

Dietary phenolic compounds as promising therapeutic agents for diabetes and its complications: A comprehensive review

In the middle of an ever-changing landscape of diabetes care, precision medicine, and lifestyle therapies are becoming increasingly important. Dietary polyphenols are like hidden allies found in our everyday meals. These biomolecules, found commonly in fruits, vegetables, and various plant-based sources, hold revolutionary potential within their molecular structure in the way we approach diabetes and its intimidating consequences. There are currently numerous types of diabetes medications, but they are not appropriate for all patients due to limitations in dosages, side effects, drug resistance, a lack of efficacy, and ethnicity. Currently, there has been increased interest in practicing herbal remedies to manage diabetes and its related complications. This article aims to summarize the potential of dietary polyphenols as a foundation in the treatment of diabetes and its associated consequences. We found that most polyphenols inhibit enzymes linked to diabetes. This review outlines the potential benefits of selected molecules, including kaempferol, catechins, rosmarinic acid, apigenin, chlorogenic acid, and caffeic acid, in managing diabetes mellitus as these compounds have exhibited promising results in in vitro, in vivo, in silico, and some preclinical trials study. This encompassing exploration reveals the multifaceted impact of polyphenols not only in mitigating diabetes but also in addressing associated conditions like inflammation, obesity, and even cancer. Their mechanisms involve antioxidant functions, immune modulation, and proinflammatory enzyme regulation. Furthermore, these molecules exhibit anti-tumor activities, influence cellular pathways, and activate AMPK pathways, offering a less toxic, cost-effective, and sustainable approach to addressing diabetes and its complications.

Multi-omics analyses reveal relationships among polyphenol-rich oolong tea consumption, gut microbiota, and metabolic profile: A pilot study

Convincing evidence has suggested the health potentials of oolong tea (OT) on gut microbiota homeostasis; however, limited population-based studies exist regarding the effect of OT consumption on human gut microbial and metabolic profile. This pilot study explored gut microbial and metabolic changes in healthy adults with a 3-week oolong tea intake. Our findings showed that OT treatment significantly altered gut microbial diversity (Shannon index, 5.4±0.1 vs. 5.7±0.1 pre- and post-OT treatment), reorganized gut microbiota composition, enriched Bacteroides and Prevotella, decreased Megamonas, and improved gastrointestinal function. Also, gut microbes from overweight subjects with BMI >23.9 exhibited greater responses to OT treatment compared with normal-weight counterparts. Metabolomic analysis identified OT intake-induced 23 differential metabolites and 10 enriched metabolic pathways. This study may provide new insights into the association among OT intervention, host gut microbiome and metabolic profile, and improve the knowledge of clinical strategies and personalized nutrition.

Polyphenol-rich oolong tea alleviates obesity and modulates gut microbiota in high-fat diet-fed mice

Obesity is a major public health issue worldwide. Oolong tea (OT), which is partially fermented from Camellia sinensis leaves, has proven health benefits and potential preventive applications in multiple studies. However, research on the role of OT in obesity prevention and potential mechanisms is still limited. The purpose of this study was to investigate the modulatory effects of OT intervention on high-fat diet (HFD)-induced obesity and gut microbiota dysbiosis using an obese mouse model. Our results showed that 8-week OT supplementation with 93.94% polyphenols significantly decreased body weight gain, adipose tissue mass, and serum levels of triglyceride (2.60 mmol/L), cholesterol (5.49 mmol/L), and low-density lipoprotein cholesterol (0.61 mmol/L) in HFD-fed mice. Meanwhile, OT intervention was observed to improve fat accumulation, hepatic damage, glucose intolerance, and endotoxemia and alleviate inflammation by decreasing the levels of pro-inflammatory factors. OT also upregulated the expression of genes including Srebf1, Ppara, Lxra, Pgc1a, and Hsl and downregulated the expression of genes including Leptin, Il-6, and Il-1b. In addition, the gut dysbiosis characterized by decreased flora diversity and increased Firmicutes/Bacteroidetes ratio in obese mice was recovered by OT intervention. Certain differentially abundant microbes caused by HFD feeding, including Enterococcus, Intestinimonas, Blautia, and Bilophila, were also improved by OT treatment. This study demonstrated that OT, as a novel resource of dietary polyphenols, exhibited a protective effect on HFD-induced obesity and gut microbiota disorder.

Effect of Green Tea on Weight Gain and Semen Quality of Rabbit Males

The goal of the current study was to evaluate the action of the green tea plant (Camellia sinensis, L) on male rabbit reproduction and some non-reproductive indexes. Male rabbits were fed either a standard diet (control group) or a diet enriched with green tea powder (experimental groups; E): 5 g (E1) or 20 g (E2) per 100 kg of the milled complete feed mixture. Weight gain, sperm concentration, total and progressive motility, as well as haematological, and biochemical parameters and changes in testicular tissue histomorphology were evaluated. Feeding with green tea, at both tested concentrations, decreased weight gain per week and the total average weight gain compared to the control group (p < 0.05). Furthermore, green tea decreased sperm concentration, motility and progressive motility in the group fed with a lower dose (5 g) of green tea powder (p < 0.05), whilst a higher dose (20 g) was neutral. Some haematological and biochemical indexes, like medium-size cell count (MID), mean corpuscular haemoglobin concentration (MCHC), platelet percentage (PCT), levels of phosphorus (P) and total proteins (TP) were decreased in one or both experimental groups (p < 0.05), whilst the triglyceride level (TG) was increased in the E2 group (p < 0.05). The thicknesses of the testicular seminiferous tubules and epithelial layer were not affected by any concentration of green tea powder (p > 0.05). These observations suggest that green tea in the diet may have an adverse effect on rabbit growth and sperm quality, but their effect may be potentially dose-dependent.

HPLC-DAD Based Polyphenolic Profiling and Evaluation of Pharmacological Attributes of Putranjiva roxburghii Wall

The current study was intended to explore the phytochemical profiling and therapeutic activities of Putranjiva roxburghii Wall. Crude extracts of different plant parts were subjected to the determination of antioxidant, antimicrobial, antidiabetic, cytotoxic, and protein kinase inhibitory potential by using solvents of varying polarity ranges. Maximum phenolic content was notified in distilled water extracts of the stem (DW-S) and leaf (DW-L) while the highest flavonoid content was obtained in ethyl acetate leaf (EA-L) extract. HPLC-DAD analysis confirmed the presence of various polyphenols, quantified in the range of 0.02 ± 0.36 to 2.05 ± 0.18 μg/mg extract. Maximum DPPH scavenging activity was expressed by methanolic extract of the stem (MeOH-S). The highest antioxidant capacity and reducing power was shown by MeOH-S and leaf methanolic extract (MeOH-L), respectively. Proficient antibacterial activity was shown by EA-L extract against Bacillus subtilis and Escherichia coli. Remarkable α-amylase and α-glucosidase inhibition potential was expressed by ethyl acetate fruit (EA-F) and n-Hexane leaf (nH-L) extracts, respectively. In case of brine shrimp lethality assay, 41.67% of the extracts (LC₅₀ < 50 µg/mL) were considered as extremely cytotoxic. The test extracts also showed mild antifungal and protein kinase inhibition activities. The present study explores the therapeutic potential of P. roxburghii and calls for subsequent studies to isolate new bioactive leads through bioactivity-guided isolation.

Multiple Risk Factors for Heart Disease: A Challenge to the Ethnopharmacological Use of Croton urucurana Baill

Croton urucurana Baill. is a native Brazilian tree, popularly known as "sangra-d'água" or "sangue-de-dragão," based on the red resinous sap of the trunk. Its use has been transmitted through generations based on popular tradition that attributes analgesic, anti-inflammatory, and cardioprotective properties to the tree. However, its cardioprotective effects have not yet been scientifically investigated. Thus, the present study investigated the pharmacological response to an ethanol-soluble fraction from the leaves of C. urucurana in Wistar rats exposed to smoking and dyslipidemia, two important cardiovascular risk factors. The extract was evaluated by high-performance liquid chromatography. Wistar rats received a 0.5% cholesterol-enriched diet and were exposed to cigarette smoke (9 cigarettes/day for 10 weeks). During the last 5 weeks, the animals were orally treated with vehicle (negative control group), C. urucurana extract (30, 100, and 300 mg/kg), or simvastatin (2.5 mg/kg) + enalapril (15 mg/kg). One group of rats that was not exposed to these risk factors was also evaluated (basal group). Electrocardiograms and systolic, diastolic, and mean blood pressure were measured. Blood was collected to measure total cholesterol, triglycerides, urea, and creatinine. The heart and kidneys were collected and processed for oxidative status and histopathological evaluation. The phytochemical analysis revealed different classes of flavonoids and condensed tannins. The model induced dyslipidemia and cardiac and renal oxidative stress and increased levels of urea and creatinine in the negative control group. Treatment with the C. urucurana extract (300 mg/kg) and simvastatin + enalapril decreased cholesterol and triglyceride levels. In contrast to simvastatin + enalapril treatment, the C. urucurana extract exerted cardiac and renal antioxidant effects. No alterations of electrocardiograms, blood pressure, or histopathology were observed between groups. These findings indicate that C. urucurana exerts lipid-lowering, renal, and cardioprotective effects against oxidative stress in a preclinical model of multiple risk factors for heart disease.

Liver biomarkers in adults: Evaluation of associations with reported green tea consumption and use of green tea supplements in U.S. NHANES

Some events of hepatotoxicity have been linked to consumption of green tea supplements. The association between consumption of green tea or green tea supplements and abnormal liver biomarkers in adults was investigated using cross-sectional data from the 2009-2014 United States National Health and Nutrition Examination Survey (U.S. NHANES). Individuals with levels of either bilirubin or GGT, ALT, AST, and/or ALP in excess of the age- and gender-specific upper limits of normal ranges were classified as having abnormal liver biomarkers. Associations between green tea or green tea supplement use (consumption vs. not) and liver function were determined using multiple logistic regression modelling. 12,289 persons were included in the green tea analyses and 12,274 in the green tea supplement analyses. The odds of having one or more abnormal liver biomarkers were significantly reduced (p = 0.01) with consumption of green tea (OR: 0.49; 95% CI: 0.28, 0.85), while no significant association (p = 0.78) was determined for consumption of green tea supplements (OR: 0.92; 95% CI: 0.52, 1.64). Based on data from the 2009-2014 U.S. NHANES, green tea consumption was associated with reduced odds of having one or more abnormal liver biomarkers; whereas, no significant association was determined with consumption of green tea supplements.

Effect of Green Tea Supplementation on Antioxidant Status in Adults: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

It is well-established that green tea supplementation has antioxidant properties. However, whether green tea supplementation leads to oxidative stress reduction remains unclear, as clinical investigations on this subject have yielded inconsistent outcomes. Consequently, we aimed to determine the effects of green tea supplementation on oxidative stress in adults. A systematic search of English language publications up to 21 August 2021 was carried out in PubMed, Scopus, Embase, and ISI Web of Science, utilizing pertinent keywords. These searches included randomized controlled trials (RCTs) evaluating the relationship between green tea supplementation, malondialdehyde (MDA), and total antioxidant capacity (TAC) in adults. A random-effects model was used to estimate the weighted mean difference (WMD) and 95% confidence intervals (95% CI). Meta-regression and non-linear dose-response analyses were performed to investigate the association between the dosage of green tea (mg/day) and the duration of the intervention (weeks) with pooled effect size. Sixteen RCTs with seventeen arms including 760 participants met the inclusion criteria. Our results indicated that green tea supplementation had significant effects on TAC (weighted mean difference [WMD]: 0.20 mmol/L; 95% CI: 0.09, 0.30, p < 0.001) and significant heterogeneity between studies (I² = 98.6%, p < 0.001), which was largely related to gender and body mass index (BMI). Subgroup analysis in TAC identified a significant relationship except with low dose supplementation and obese individuals. No relationship between MDA and green tea supplementation was observed in any subgroups; however, meta-regression analysis revealed a linear inverse association between the dosage and significant change in MDA (r = −2117.18, p = 0.017). Our outcomes suggest that green tea supplementation improves TAC and affects MDA based on the dose of the intervention in adults. Future RCTs with longer durations are needed to expand our findings.

Aged Ripe Pu-erh Tea Reduced Oxidative Stress-Mediated Inflammation in Dextran Sulfate Sodium-Induced Colitis Mice by Regulating Intestinal Microbes

Ripened pu-erh tea has the biological activity of antioxidation and anti-inflammation, which inhibits the related parameters of colitis. However, the role of storage-induced changes in bioactive ingredients of ripened pu-erh tea in colitis remains unclear. In this study, 3.5% dextran sulfate sodium-induced colitis mice were treated with 10 mg/kg bw/day extracts, aged 14 years (P2006) and unaged (P2020) ripened pu-erh tea, respectively, for 1 week. We found that ripened pu-erh tea, especially P2006, inhibited the intestinal oxidative stress-mediated inflammation pathway (TLR4/MyD88/ROS/p38MAPK/NF-κB p65), upregulated the expression of intestinal tight junction proteins (Mucin-2, ZO-1, occludin), promoted M2 polarization of macrophages, and in turn, improved the intestinal immune barrier, which stemmed from the reshaping of intestinal microbiota (e.g., increased Lachnospiraceae_NK4A136_group and Akkermansia levels). Our results speculate that drinking aged ripe pu-erh tea (10 mg/kg bw/day in mice, a human equivalent dose of 7 g/60 kg bw/day) has a practical effect on alleviating and preventing the development of intestinal inflammation.

Increasing the Power of Polyphenols through Nanoencapsulation for Adjuvant Therapy against Cardiovascular Diseases

Polyphenols play a therapeutic role in vascular diseases, acting in inherent illness-associate conditions such as inflammation, diabetes, dyslipidemia, hypertension, and oxidative stress, as demonstrated by clinical trials and epidemiological surveys. The main polyphenol cardioprotective mechanisms rely on increased nitric oxide, decreased asymmetric dimethylarginine levels, upregulation of genes encoding antioxidant enzymes via the Nrf2-ARE pathway and anti-inflammatory action through the redox-sensitive transcription factor NF-κB and PPAR-γ receptor. However, poor polyphenol bioavailability and extensive metabolization restrict their applicability. Polyphenols carried by nanoparticles circumvent these limitations providing controlled release and better solubility, chemical protection, and target achievement. Nano-encapsulate polyphenols loaded in food grade polymers and lipids appear to be safe, gaining resistance in the enteric route for intestinal absorption, in which the mucoadhesiveness ensures their increased uptake, achieving high systemic levels in non-metabolized forms. Nano-capsules confer a gradual release to these compounds, as well as longer half-lives and cell and whole organism permanence, reinforcing their effectiveness, as demonstrated in pre-clinical trials, enabling their application as an adjuvant therapy against cardiovascular diseases. Polyphenol entrapment in nanoparticles should be encouraged in nutraceutical manufacturing for the fortification of foods and beverages. This study discusses pre-clinical trials evaluating how nano-encapsulate polyphenols following oral administration can aid in cardiovascular performance.

Impact of functional foods and nutraceuticals on high blood pressure with a special focus on meta-analysis: review from a public health perspective

In recent times many researchers are expressing immense interest in nutraceuticals and functional foods for combating various diseases or abnormal conditions, especially against hypertension (HT). Persistent HT is medically referred to as chronic high blood pressure (BP) and considered to be one of the major risk factors for the deadliest diseases including cardiovascular disease (CVD) and cerebrovascular diseases. Hence HT poses a serious socio-economic burden worldwide, particularly to developing countries. The current treatment strategy for HT includes standard anti-hypertensive drugs, which are associated with many adverse effects and lower drug adherence rates. Therefore, an alternative or complementary natural therapy (functional foods or nutraceuticals or dietary supplements) would be the alternate choice along with a modified lifestyle pattern that might help to manage or combat HT and its related complications. During this review, the author would like to shed light on the basic science behind HT including pathophysiology and the impact of dietary salt on HT and the impact of various functional foods or nutraceuticals against HT in humans (meta-analysis and systemic review). This contribution gives a better idea (public health perspective) for choosing the best functional foods/nutraceuticals for the prevention, management or delaying the onset of HT and its associated conditions along with modified lifestyle patterns and standard anti-hypertensive drugs.

Oral Administration of Flavonifractor plautii, a Bacteria Increased With Green Tea Consumption, Promotes Recovery From Acute Colitis in Mice via Suppression of IL-17

Flavonifractor plautii (FP) has been reported to participate in the metabolism of catechins in the human gut. However, there is limited information on the immune regulatory effects of this bacterium. We confirmed that the administration of green tea increases the abundance of FP in the gut microbiota and investigated the effect of FP in a mouse colitis model. Mice were orally administered FP for 10 consecutive days; colonic inflammation was evaluated daily on the basis of stool consistency, gross rectal bleeding, and body weight. In the dextran sodium sulfate model, FP-exposed animals exhibited lower levels of inflammation and strong inhibition of interleukin (IL)-17 signaling. Moreover, lipoteichoic acid from FP was identified as the active component mediating IL-17 suppression. Thus, oral administration of FP appears to modulate gut inflammation and represents a viable and inexpensive oral microbial therapeutic.

The Effects of Foods on Blood Lipids in Non-alcoholic Fatty Liver Disease (NAFLD)-A Systematic Review and Meta-Analysis

Background: Non-alcoholic fatty liver disease (NAFLD) is associated with dyslipidemia and increased cardiovascular disease risk. Dietary choices may produce profound effects on blood lipids. Thus, the purpose of this study was to investigate which foods modify blood lipids in NAFLD.

Methods: Systematic review of published systematic reviews and randomized controlled trials (RCTs). Searches were performed in PubMed, Cochrane Database of Systematic Reviews, and Cochrane Central Register of Controlled Trials, from inception through March 2020. Studies in populations with NAFLD, which provided data on foods or dietary patterns and blood lipids were included, but not weight loss diets, supplements, nor individual nutrients. The strength of evidence was evaluated using The Grading of Recommendations Assessment, Development, and Evaluation (GRADE).

Results: No relevant systematic reviews were identified. Eleven RCTs were included in the qualitative synthesis. Two RCTs were included in meta-analyses, regarding the comparison between Mediterranean and Low-fat diets, in which there were no clear effects on either high-density lipoprotein cholesterol or triglycerides, with Low evidence. From single RCTs, there was Moderate evidence for reduced triglycerides by a healthy dietary pattern, compared with usual care; and for reduced total cholesterol by a probiotic yogurt, enriched with Lactobacillus acidophilus La5 and Bifidobacterium lactis Bb12, compared with conventional yogurt. For all other comparisons, the evidence was considered as Low or Very low.

Conclusion: Few studies were identified which reported effects of foods on blood lipids in subjects with NAFLD. The possible beneficial effect of probiotics warrants further study. PROSPERO identifier: CRD42020178927.

The role of nutraceuticals as a complementary therapy against various neurodegenerative diseases: A mini-review

In recent times, many scientists have given great attention to nutraceuticals (complementary medicine) as it widely used for promoting health status. In particular for the prevention and treatment of various neurological diseases or disorders without or less adverse effects. The current mini-review was intended to compile all popular (major) nutraceuticals against various neurodegenerative diseases (NDDs) including Parkinson's disease (PD), Alzheimer's disease (AD), Huntington's disease (HD) with special reference to clinical trials. Preliminary reviews indicated that nutraceuticals like curcumin, resveratrol, Epigallocatechin-3-gallate (EGCG), Coenzyme Q10, ω-3 FA (DHA/EPA/ALA), showed better neuroprotective activity against various NDDs in human setting (clinical trial). Hence this contribution will focus only on those popular nutraceuticals with proposed brief mechanisms (antioxidant, anti-inflammatory, mitochondrial homeostasis, autophagy regulation, promote neurogenesis) and its recommendation. This mini-review would aid common people to choose better nutraceuticals to combat various NDDs along with standard neuroprotective agents and modified lifestyle pattern.

Ethnopharmacology of Fruit Plants: A Literature Review on the Toxicological, Phytochemical, Cultural Aspects, and a Mechanistic Approach to the Pharmacological Effects of Four Widely Used Species

Fruit plants have been widely used by the population as a source of food, income and in the treatment of various diseases due to their nutritional and pharmacological properties. The aim of this study was to review information from the most current research about the phytochemical composition, biological and toxicological properties of four fruit species widely used by the world population in order to support the safe medicinal use of these species and encourage further studies on their therapeutic properties. The reviewed species are: Talisia esculenta, Brosimum gaudichaudii, Genipa americana, and Bromelia antiacantha. The review presents the botanical description of these species, their geographical distribution, forms of use in popular medicine, phytochemical studies and molecules isolated from different plant organs. The description of the pharmacological mechanism of action of secondary metabolites isolated from these species was detailed and toxicity studies related to them were reviewed. The present study demonstrates the significant concentration of phenolic compounds in these species and their anti-inflammatory, anti-tumor, photosensitizing properties, among others. Such species provide important molecules with pharmacological activity that serve as raw materials for the development of new drugs, making further studies necessary to elucidate mechanisms of action not yet understood and prove the safety for use in humans.

Metabolic Impact of Flavonoids Consumption in Obesity: From Central to Peripheral

The prevention and treatment of obesity is primary based on the follow-up of a healthy lifestyle, which includes a healthy diet with an important presence of bioactive compounds such as polyphenols. For many years, the health benefits of polyphenols have been attributed to their anti-oxidant capacity as free radical scavengers. More recently it has been described that polyphenols activate other cell-signaling pathways that are not related to ROS production but rather involved in metabolic regulation. In this review, we have summarized the current knowledge in this field by focusing on the metabolic effects of flavonoids. Flavonoids are widely distributed in the plant kingdom where they are used for growing and defensing. They are structurally characterized by two benzene rings and a heterocyclic pyrone ring and based on the oxidation and saturation status of the heterocyclic ring flavonoids are grouped in seven different subclasses. The present work is focused on describing the molecular mechanisms underlying the metabolic impact of flavonoids in obesity and obesity-related diseases. We described the effects of each group of flavonoids in liver, white and brown adipose tissue and central nervous system and the metabolic and signaling pathways involved on them.

The Role of Histone Acetylation and the Microbiome in Phytochemical Efficacy for Cardiovascular Diseases

Cardiovascular diseases (CVD) are the main cause of death worldwide and create a substantial financial burden. Emerging studies have begun to focus on epigenetic targets and re-establishing healthy gut microbes as therapeutic options for the treatment and prevention of CVD. Phytochemicals, commonly found in fruits and vegetables, have been shown to exert a protective effect against CVD, though their mechanisms of action remain incompletely understood. Of interest, phytochemicals such as curcumin, resveratrol and epigallocatechin gallate (EGCG) have been shown to regulate both histone acetylation and microbiome re-composition. The purpose of this review is to highlight the microbiome-epigenome axis as a therapeutic target for food bioactives in the prevention and/or treatment of CVD. Specifically, we will discuss studies that highlight how the three phytochemicals above alter histone acetylation leading to global changes in gene expression and CVD protection. Then, we will expand upon these phytochemicals to discuss the impact of phytochemical-microbiome-histone acetylation interaction in CVD.

Effect of green tea consumption on blood lipids: a systematic review and meta-analysis of randomized controlled trials

Background

Strong epidemiologic evidence indicates that green tea intake is protective against hyperlipidemia; however, randomized controlled studies have presented varying results. In the present study, we aimed to conduct a literature review and meta-analysis to assess the effect of green tea on blood lipids.

Methods

PubMed, Embase, and the Cochrane Library were electronically explored from inception to September 2019 for all relevant studies. Random effect models were used to estimate blood lipid changes between green tea supplementation and control groups by evaluating the weighted mean differences (WMD) with 95% confidence intervals (CIs). The risk of bias for study was assessed using the Cochrane tool. Publication bias was evaluated using funnel plots and Egger’s tests.

Results

Thirty-one trials with a total of 3321 subjects were included in the meta-analysis. In general, green tea intake significantly lowered the total cholesterol (TC); WMD: − 4.66 mg/dL; 95% CI: − 6.36, − 2.96 mg/dL; P < 0.0001) and low-density lipoprotein (LDL) cholesterol (WMD:− 4.55 mg/dL; 95% CI: − 6.31, − 2.80 mg/dL; P < 0.0001) levels compared with those in the control. Green tea consumption did not affect high-density lipoprotein (HDL) cholesterol; however, it reduced the triglycerides compared with that in the control (WMD: − 3.77 mg/dL; 95% CI: − 8.90, 1.37 mg/dL; P = 0.15). In addition, significant publication bias from funnel plots or Egger’s tests was not evident.

Conclusions

Collectively, consumption of green tea lowers LDL cholesterol and TC, but not HDL cholesterol or triglycerides in both normal weight subjects and those who were overweight/obese; however, additional well-designed studies that include more diverse populations and longer duration are warranted.

The effect of green tea supplementation on obesity: A systematic review and dose-response meta-analysis of randomized controlled trials

The effects of green tea (GT) in obese subjects have been evaluated in different studies, but no consensus has been obtained due to the heterogeneity of the results. The dosage, the type of extract, and the duration of the intervention are the main contributors to the heterogeneity of the results. Therefore, the present systematic review and meta-analysis aimed to evaluate the efficacy and dose-response relationship of GT. Several databases were searched from inception to September 2019 to identify clinical trials that examined the influence of GT supplements on obesity indices in humans. Combined results using the random-effects model indicated that body weight (WMD: -1.78 kg, 95% CI: -2.80, -0.75, p = .001) and body mass index (BMI) (WMD: -0.65 kg/m² , 95% CI: -1.04, -0.25, p = .001) did change significantly following GT administration. The reduction in waist circumference (WC) after GT consumption was significant in subjects in trials employing GT ≥800 mg/day (WMD: -2.06 cm) and with a treatment duration <12 weeks (WMD: -2.39 cm). Following the dose-response evaluation, GT intake did alter body weight, with a more important reduction when the GT dosage was <500 mg/day and the treatment duration was of 12 weeks. The results of present meta-analysis study support the use of GT for the improvement of obesity indices. Thus, we suggest that the use of GT can be combined with a balanced and healthy diet and regular physical exercise in the management of obese patients.

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.

Health Functions and Related Molecular Mechanisms of Tea Components: An Update Review

Tea is widely consumed all over the world. Generally, tea is divided into six categories: White, green, yellow, oolong, black, and dark teas, based on the fermentation degree. Tea contains abundant phytochemicals, such as polyphenols, pigments, polysaccharides, alkaloids, free amino acids, and saponins. However, the bioavailability of tea phytochemicals is relatively low. Thus, some novel technologies like nanotechnology have been developed to improve the bioavailability of tea bioactive components and consequently enhance the bioactivity. So far, many studies have demonstrated that tea shows various health functions, such as antioxidant, anti-inflammatory, immuno-regulatory, anticancer, cardiovascular-protective, anti-diabetic, anti-obesity, and hepato-protective effects. Moreover, it is also considered that drinking tea is safe to humans, since reports about the severe adverse effects of tea consumption are rare. In order to provide a better understanding of tea and its health potential, this review summarizes and discusses recent literature on the bioactive components, bioavailability, health functions, and safety issues of tea, with special attention paid to the related molecular mechanisms of tea health functions.

Effects and Mechanisms of Tea and Its Bioactive Compounds for the Prevention and Treatment of Cardiovascular Diseases: An Updated Review

Cardiovascular diseases (CVDs) are critical global public health issues with high morbidity and mortality. Epidemiological studies have revealed that regular tea drinking is inversely associated with the risk of CVDs. Additionally, substantial in vitro and in vivo experimental studies have shown that tea and its bioactive compounds are effective in protecting against CVDs. The relevant mechanisms include reducing blood lipid, alleviating ischemia/reperfusion injury, inhibiting oxidative stress, enhancing endothelial function, attenuating inflammation, and protecting cardiomyocyte function. Moreover, some clinical trials also proved the protective role of tea against CVDs. In order to provide a better understanding of the relationship between tea and CVDs, this review summarizes the effects of tea and its bioactive compounds against CVDs and discusses potential mechanisms of action based on evidence from epidemiological, experimental, and clinical studies.

Clinical Advances in Immunonutrition and Atherosclerosis: A Review

Atherosclerosis is a chronic low-grade inflammatory disease that affects large and medium-sized arteries and is considered to be a major underlying cause of cardiovascular disease (CVD). The high risk of mortality by atherosclerosis has led to the development of new strategies for disease prevention and management, including immunonutrition. Plant-based dietary patterns, functional foods, dietary supplements, and bioactive compounds such as the Mediterranean Diet, berries, polyunsaturated fatty acids, ω-3 and ω-6, vitamins E, A, C, and D, coenzyme Q10, as well as phytochemicals including isoflavones, stilbenes, and sterols have been associated with improvement in atheroma plaque at an inflammatory level. However, many of these correlations have been obtained in vitro and in experimental animals' models. On one hand, the present review focuses on the evidence obtained from epidemiological, dietary intervention and supplementation studies in humans supporting the role of immunonutrient supplementation and its effect on anti-inflammatory response in atherosclerotic disease. On the other hand, this review also analyzes the possible molecular mechanisms underlying the protective action of these supplements, which may lead a novel therapeutic approach to prevent or attenuate diet-related disease, such as atherosclerosis.

Green tea can supress rabbit ovarian functions in vitro and in vivo

The aim of present study was to evaluate the action of green tea and its constituents on rabbit ovarian functions and some non-reproductive indexes. In in vitro experiments, rabbit ovarian fragments were cultured with green tea constituents - epigallocatechin-3-gallate (EGCG), green tea polyphenols (GTPP) and resveratrol (RSV) (at 0, 1, 10 or 100 μg/mL medium). The accumulation of an apoptosis marker - caspase 3 and the release of progesterone (P4) and testosterone (T) were measured. In in vivo experiments, does were fed a standard diet or a diet enriched with green tea powder. The weight gain, mortality, ovarian length and weight, conception and kindling rate, number of liveborn, stillborn, and weaned pups, diameter of ovarian follicles and some blood haematological and biochemical parameters were analysed. Culture of ovarian fragments with EGCG increased accumulation of caspase 3, whilst both GTTP and RSV decreased it. EGCG inhibited both P4 and T output, GTPP stimulated P4 and inhibited T, whilst RSV promoted release of both P4 and T. Feeding with green tea increased ovarian length and diameter of ovarian non-ovulated peri-ovulatory haemorrhagic but not of primary and secondary growing follicles. Furthermore, green tea reduced conception and kindling rate, the number of liveborn and weaned pups, increased female mortality but not their weight gain. It reduced platelet distribution width, but it did not affect other haematological and biochemical indexes. These observations suggest that dietary green tea can reduce rabbit doe's viability, ovarian functions and fecundity, perhaps due to changes in ovarian cell apoptosis, steroid hormones release and blockade of the ovulation of large ovarian follicles. The anti-reproductive action of green tea could be due to its constituent - EGCG with pro-apoptotic and anti-steroid hormone properties.

Extensive review of popular functional foods and nutraceuticals against obesity and its related complications with a special focus on randomized clinical trials

Weight management (anti-obesity) by popular functional foods and nutraceuticals.

Oolong tea polysaccharide and polyphenols prevent obesity development in Sprague-Dawley rats

Background

Several studies have evaluated the effects of oolong tea extracts on obesity. However, only few studies focused on the anti-obesity effect of specific components of oolong tea.

Objective

This study investigated the specific anti-obesity capabilities of oolong tea polysaccharide (TPS) and tea polyphenols (TPP) in high-fat diet-induced Sprague–Dawley rats.

Methods

Oolong tea water extract, TPS, TPP, and polysaccharide mixed with polyphenol (TPSM) given at doses of 400 or 800 mg/kg were administered to rats fed with high-fat diet for 6 weeks to explore the anti-obesity effects of the treatments.

Results

TPS and TPP were responsible for the suppressive effect on body fat accumulation. TPSM exhibited the highest effect on body weight reduction, and TPS and TPP effectively reduced serum leptin levels and significantly improved blood lipid and antioxidant levels. Moreover, microarray analysis of hepatic and adipose gene expression profiles revealed that TPP and TPS inhibited obesity through effects on the pathways of fatty acid biosynthesis, steroid hormone biosynthesis, unsaturated fatty acid biosynthesis, fatty acid elongation, glycerolipid metabolism, and glycerophospholipid metabolism.

Conclusions

TPSM might be a potential therapy for the treatment of obesity.