Effect of Turmeric Supplementation on Blood Pressure and Serum Levels of Sirtuin 1 and Adiponectin in Patients with Nonalcoholic Fatty Liver Disease: A Double-Blind, Randomized, Placebo-Controlled Trial

The Effects of Curcuminoids Supplementation on Serum Adipokines: An Umbrella Review of Meta-Analyses of Randomized Controlled Trials

This umbrella review of randomized clinical trials aims to provide a unique and detailed understanding of curcumin's effects on adipokines, adding a novel perspective to the existing body of research. We carried out a thorough search of international databases up to April 2024, including MEDLINE, SciVerse Scopus, and Clarivate Analytics Web of Science. A random-effects model was utilized to evaluate the impact of curcuminoid on adipokines. The umbrella review incorporated meta-analyses that examined the effects of curcuminoid supplementation on adipokines, presenting associated effect sizes (ES) and confidence intervals (CI). We applied the GRADE and AMSTAR (A Tool for Assessing the Risk of Bias in Systematic Reviews system) to assess the certainty of the evidence and the quality of the systematic reviews. Our analysis of one meta-analysis, including 14 RCTs plus 1 RCT not included in meta-analyses, revealed significant and impactful findings. We found a substantial increase in serum adiponectin levels with curcuminoid supplementation, indicating a positive effect (SMD: 0.9; 95% CI, 0.4 to 1.3, p < 0.001; I2 = 92.2%). However, we did not observe a significant impact on serum leptin. The GRADE assessment supports the effect of curcuminoids on adiponectin with moderate evidence, while the impact on leptin was supported by low evidence. Curcuminoid supplementation significantly increases serum adiponectin levels with moderate-quality evidence and has no significant impact on serum leptin. This provides evidence as to the safety and effectiveness of curcuminoids in enhancing adiponectin without adverse effects, reassuring the audience about their potential in adipokine research.

The clinical value of serum sirtuin-1 concentration in the diagnosis of metabolic dysfunction-associated steatotic liver disease

BACKGROUND

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most prevalent chronic liver disease and can affect individuals without producing any symptoms. We aimed to explore the value of serum sirtuin-1 (Sirt-1) in the diagnosis of MASLD.

METHODS

This case-control study analyzed data collected from 190 individuals aged 20 to 60 years. Anthropometric parameters, demographic information, and serum biochemical variables-including glycemic parameters, lipid profiles, liver enzymes, and Sirt-1 levels-were assessed. The correlation between serum Sirt-1 and biochemical variables was examined using Pearson's correlation coefficient. Receiver operating characteristic (ROC) curve analysis was employed to evaluate the diagnostic value of serum Sirt-1 in the context of MASLD.

RESULTS

Serum Sirt-1 levels was significantly lower in the MASLD group (p < 0.001) and was inversely correlated with serum insulin (r = -0.163, p = 0.025), HOMA-IR (r = -0.169, p = 0.020) and triglyceride (r = -0.190, p = 0.009) and positively correlated with serum levels of high-density lipoprotein cholesterol (HDL-C) (r = 0.214, p = 0.003). The area under the curve (AUC) of Sirt-1 to predict the presence of MASLD was 0.76 (p < 0.001, 95% CI: 0.69, 0.82) with a sensitivity of 78.9, specificity of 61.1, positive predictive value (PPV) of 67.0%, and negative predictive value (NPV) of 74.0%. The optimal cutoff, determined using Youden's index, was 23.75 ng/mL. This indicates that serum Sirt-1 levels below 23.75 ng/mL may be indicative of MASLD.

CONCLUSIONS

The present study demonstrated that serum Sirt-1 levels were significantly lower in patients with MASLD. Furthermore, these levels were correlated with various metabolic parameters, including insulin resistance and the serum lipid profile. A serum Sirt-1 level below the cutoff of 23.75 ng/mL exhibited a significant association with the presence of MASLD, suggesting its potential utility in identifying patients with this condition.

A Golden Shield: The Protective Role of Curcumin against Liver Fibrosis

Several chronic liver injuries can result in liver fibrosis, a wound-healing response defined by an excessive buildup of diffuse extracellular matrix (ECM). Liver fibrosis may progress to liver cirrhosis, liver failure, or hepatocellular carcinoma. Many cellular routes are implicated in the fibrosis process; however, hepatic stellate cells appear to be the main cell type involved. Curcumin, a polyphenolic substance extracted from the Curcuma longa plant, has a diversity of pharmacologic impacts, including anti- inflammatory, antioxidant, antiproliferative and antiangiogenic actions. The anti-fibrotic property of curcumin is less clear, but curcumin's ability to influence inflammatory cytokines, inflammatory pathways, the expression of pro-apoptotic (up-regulated) and anti- apoptotic (down-regulated) proteins, and its ability to lower oxidative stress likely underlie its anti-fibrotic properties. In this review, we investigate and analyze the impact of curcumin on several disorders that lead to liver fibrosis, and discuss the therapeutic applications of curcumin for these disorders.

Therapeutic effects of curcumin supplementation on liver enzymes of nonalcoholic fatty liver disease patients: A systematic review and meta-analysis of randomized clinical trials

Curcumin, as an antioxidant agent, has been proposed as a potential treatment for nonalcoholic fatty liver disease (NAFLD). The aim of the current systematic review and meta-analysis was to summarize earlier findings regarding the effect of curcumin supplementation on liver enzymes and ALP in NAFLD patients. All studies published up to November 18, 2022, were searched through the PubMed, SCOPUS, and Web of Science databases to collect all randomized clinical trials (RCTs) on NAFLD patients in which curcumin was used as a treatment. A random-effects model was used to measure pooled effect sizes. Weighted mean differences (WMDs) and 95% confidence intervals (CIs) were used to report pooled effect sizes. Subgroup analysis was utilized to investigate heterogeneity. A total of 14 studies were included in this systematic review and meta-analysis. Our pooled meta-analysis indicated a significant decrease in alanine aminotransferase (ALT) following curcumin therapy by pooling 12 effect sizes (WMD: -8.72; 95% CI: -15.16, -2.27, I 2 = 94.1%) and in aspartate aminotransferase (AST) based on 13 effect sizes (WMD: -6.35; 95% CI: -9.81, -2.88, I 2 = 94.4%). However, the pooled analysis of five trials indicated that there was no significant association between curcumin therapy and alkaline phosphatase (ALP) in NAFLD patients (WMD: -4.71; 95% CI: -13.01, 3.58, I 2 = 64.2%). Nevertheless, subgroup analyses showed significant effects of curcumin on ALP with a longer duration of supplementation. The findings of this systematic review and meta-analysis support the potential effect of curcumin on the management of NAFLD. Further randomized controlled trials should be conducted in light of our findings.

The Effectiveness of Curcumin, Resveratrol, and Silymarin on MASLD: A Systematic Review and Meta-Analysis

Polyphenols, known for their potent antioxidant and anti-inflammatory properties, have emerged as promising, natural, and safe complementary treatment options for metabolic-associated steatotic liver disease (MASLD). Among these, curcumin, resveratrol, and silymarin are the most extensively studied; however, their differential effects on MASLD outcomes remain inconclusive. This systematic review and meta-analysis of RCTs aimed to evaluate the efficacy of curcumin, resveratrol, and silymarin in patients with MASLD. A comprehensive search of seven databases was conducted up to September 2024. Odds ratios (OR), mean differences (MD), and standardized MD (SMD) with 95% confidence intervals (CI) were used to assess treatment effects. Primary outcomes included improvement in hepatic steatosis and ALT activity, while secondary outcomes included changes in AST activity, blood lipids, glucose, BMI, blood pressure, and TNF-α. Twenty-seven studies involving 1691 participants were included. Curcumin significantly improved hepatic steatosis compared to placebo (OR: 4.39, 95% CI: 1.45 to 13.27, p = 0.009), followed by resveratrol (OR: 3.18, 95% CI: 1.20 to 8.42, p = 0.02). Silymarin exhibited the strongest effect in reducing ALT levels (MD: -6.44 U/L, 95% CI: -10.03 to -2.85, p = 0.0004), with curcumin (MD: -5.88 U/L, 95% CI: -9.05 to -2.72, p = 0.0003) also showing significant reductions. A marked reduction in AST was observed with silymarin (MD: -6.99 U/L, 95% CI: -8.56 to -5.42, p < 0.00001), followed by curcumin (MD: -3.36 U/L, 95% CI: -5.35 to -1.36, p = 0.001). Furthermore, curcumin intake significantly improved metabolic indicators (TG, FBG, HOMA-IR, and BMI). Resveratrol reduced FBG and DBP. Curcumin had the strongest effect on hepatic steatosis and improved both transaminase levels and metabolic markers. Silymarin demonstrated the greatest reduction in transaminase levels, while resveratrol showed modest benefits in steatosis and metabolic improvements. The three polyphenols appear as promising therapeutics for the treatment of MASLD.

Polyphenol Intervention Ameliorates Non-Alcoholic Fatty Liver Disease: An Updated Comprehensive Systematic Review

Non-alcoholic fatty liver disease (NAFLD) has recently emerged as a challenging metabolic disorder with a strong emphasis on its prevention and management. Polyphenols, a group of naturally occurring plant compounds, have been associated with a decreased risk of various metabolic disorders related to NAFLD. The current systematic review aims to critically assess evidence about the ameliorative effect of polyphenol supplementation on NAFLD patients. A PRISMA systematic search appraisal was conducted in PubMed, Scopus, Web of Science Core Collection, and all relevant studies published prior to April 2024 and met the inclusion criteria were included. Twenty-nine randomized clinical trials (RCTs) comprised 1840 NAFLD patients. The studies primarily examined eleven phenolic compounds, including turmeric, curcumin, resveratrol, genistein, catechin, green tea extract, hesperidin, and silymarin. Turmeric and curcumin decreased liver enzymes, inflammatory cytokines, lipid profile, insulin resistance, and NAFLD score, while resveratrol did not present consistent results across all the studies. Most studies on silymarin showed a reduction in liver enzymes and lipid profile; however, no changes were observed in inflammatory cytokine levels. The dietary supplementation of hesperidin and naringenin or green tea extract caused improvements in liver enzyme, lipid profile, and inflammatory cytokine, while genistein supplementation did not modulate blood lipid profile. In conclusion, dietary supplementation of polyphenols could potentially prevent and ameliorate NAFLD. Still, the inconsistent results across the included RCTs require further clinical research to establish optimal dosage and duration.

Protective Effects of Plum on Liver and Gut Injury in Metabolic Dysfunction-Associated Fatty Liver Disease

Metabolic dysfunction-associated fatty liver disease (MASLD), a persistent liver condition associated with metabolic syndrome, is primarily caused by excessive fructose intake and a typical Western diet. Because there is currently only one approved treatment, lifestyle and dietary interventions are crucial. This study assessed the effects of dietary intervention involving freeze-dried plum (FDP), a natural source of antioxidants containing diverse polyphenols. This study aimed to assess its potential as a protective agent against the gut-liver axis and its therapeutic effects on liver injury and gut permeability issues associated with MASLD. We indicate that 10% FDP intake restored gut barrier proteins and reduced serum endotoxin levels in the MASLD mouse models. Additionally, 10% FDP intake significantly reduced hepatic oxidative stress, lipid metabolism, and fibrosis marker levels. Interestingly, FDP intake significantly reduced the levels of inflammatory cytokine tumor necrosis factor-α and markers of liver damage, such as serum alanine aminotransferase/aspartate aminotransferase and hepatic triglycerides. These results highlight that dietary intervention with FDP that acts as a natural antioxidant may be a significant protective and therapeutic agent against liver and gut damage caused by MASLD.

Is Curcumin Intake Really Effective for Chronic Inflammatory Metabolic Disease? A Review of Meta-Analyses of Randomized Controlled Trials

This review aimed to examine the effects of curcumin on chronic inflammatory metabolic disease by extensively evaluating meta-analyses of randomized controlled trials (RCTs). We performed a literature search of meta-analyses of RCTs published in English in PubMed®/MEDLINE up to 31 July 2023. We identified 54 meta-analyses of curcumin RCTs for inflammation, antioxidant, glucose control, lipids, anthropometric parameters, blood pressure, endothelial function, depression, and cognitive function. A reduction in C-reactive protein (CRP) levels was observed in seven of ten meta-analyses of RCTs. In five of eight meta-analyses, curcumin intake significantly lowered interleukin 6 (IL-6) levels. In six of nine meta-analyses, curcumin intake significantly lowered tumor necrosis factor α (TNF-α) levels. In five of six meta-analyses, curcumin intake significantly lowered malondialdehyde (MDA) levels. In 14 of 15 meta-analyses, curcumin intake significantly reduced fasting blood glucose (FBG) levels. In 12 of 12 meta-analyses, curcumin intake significantly reduced homeostasis model assessment of insulin resistance (HOMA-IR). In seven of eight meta-analyses, curcumin intake significantly reduced glycated hemoglobin (HbA1c) levels. In eight of ten meta-analyses, curcumin intake significantly reduced insulin levels. In 14 of 19 meta-analyses, curcumin intake significantly reduced total cholesterol (TC) levels. Curcumin intake plays a protective effect on chronic inflammatory metabolic disease, possibly via improved levels of glucose homeostasis, MDA, TC, and inflammation (CRP, IL-6, TNF-α, and adiponectin). The safety and efficacy of curcumin as a natural product support the potential for the prevention and treatment of chronic inflammatory metabolic diseases.

The effect of curcumin supplementation on circulating adiponectin and leptin concentration in adults: a GRADE-assessed systematic review and meta-analysis of randomised controlled trials

Curcumin is a phytocompound found in the root of turmeric, a common herbal ingredient in many Asian cuisines. The compound contains anti-inflammatory activity, which is mediated through an upregulation of adiponectin and reduction of leptin. Results of randomised controlled trials (RCT) have shown that the effects of curcumin on adipokines are conflicting. Therefore, the current systematic review and meta-analysis of RCT were conducted with the aim of elucidating the role of curcumin supplementation on serum adiponectin and leptin. The search included PubMed, Embase, Cochrane Library, Scopus, Web of Science and Google Scholar from inception to August 2023. For net changes in adipokines, standardised mean differences (SMD) were calculated using random effects models. Thirteen RCT with fourteen treatment arms were eligible for inclusion in this meta-analysis. Curcumin supplementation was effective in increasing serum adiponectin (SMD = 0·86, 95 % CI (0·33, 1·39), P < 0·001; I2 = 93·1 %, P < 0·001) and reducing serum leptin (SMD = -1·42, 95 % CI (-2·29, -0·54), P < 0·001; I2 = 94·7 %, P < 0·001). In conclusion, curcumin supplementation significantly increased circulating adiponectin and decreased leptin levels in adults.

Curcumin effects on glycaemic indices, lipid profile, blood pressure, inflammatory markers and anthropometric measurements of non-alcoholic fatty liver disease patients: A systematic review and meta-analysis of randomized clinical trials

OBJECTIVES

Curcumin has antioxidant properties and has been proposed as a potential treatment for NAFLD. The aim of current systematic review and meta-analysis was to evaluate previous findings for the effect of curcumin supplementation on glycaemic indices, lipid profile, blood pressure, inflammatory markers, and anthropometric measurements of NAFLD patients.

METHODS

Relevant studies published up to January 2024 were searched systematically using the following databases: PubMed, SCOPUS, WOS, Science Direct, Ovid and Cochrane. The systematic review and meta-analysis were conducted according to the 2020 PRISMA guidelines. The quality of the papers was assessed the using the Joanna Briggs Institute (JBI) Critical Appraisal Checklist. Pooled effect sizes were calculated using a random-effects model and reported as the WMD and 95% CI. Also, subgroup analyses were done to find probable sources of heterogeneity among studies.

RESULTS

Out of 21010 records initially identified, 21 eligible RCTs were selected for inclusion in a meta-analysis. Overall, 1191 participants of both genders, 600 in the intervention and 591 in the control group with NAFLD were included. There are several limitations in the studies that were included, for instance, the results are weakened substantially by potential bias or failure to account for potential adulteration (with pharmaceuticals) or contamination (with other herbs) of the curcumin supplements that were tested. However, previous studies have reported curcumin to be a safe complementary therapy for several conditions. Our study indicated that curcumin supplementation in doses of 50-3000 mg/day was associated with significant change in FBG [WMD: -2.83; 95% CI: -4.61, -1.06), I2 = 51.3%], HOMA-IR [WMD: -0.52; 95% CI: -0.84, -0.20), I2= 82.8%], TG [WMD: -10.31; 95% CI: -20.00, -0.61), I2 = 84.5%], TC [WMD: -11.81; 95% CI: -19.65, -3.96), I2 = 94.6%], LDL [WMD: -8.01; 95% CI: -15.79, -0.24), I2 = 96.1%], weight [WMD: -0.81; 95% CI: -1.28, -0.35), I2= 0.0%] and BMI [WMD: -0.35; 95% CI: -0.57, -0.13), I2= 0.0%] in adults with NAFLD. There was no significant change in HbA1C, plasma insulin, QUICKI, HDL, SBP, DBP, CRP, TNF-α and WC after curcumin therapy. Subgroup analysis suggested a significant changes in serum FBG, TG, SBP, WC in RCTs for intervention durations of ≥ 8 weeks, and SBP, TG, LDL, HDL, BMI, WC in RCTs with sample size > 55 participants.

CONCLUSION

Curcumin supplementation in doses of 50-3000 mg/day over 8-12 weeks was associated with significant reductions in levels of FBG, HOMA-IR, TG, TC, LDL, weight and BMI in patients with NAFLD. Previous studies have reported curcumin as a safe complementary therapy for several diseases. We would suggest that should curcumin supplements be used clinically in specific conditions, it should be used with caution. Also, difference in grades of NAFLD may effect the evaluated outcomes, so it is suggested that future studies be conducted with an analyses on subgroups according to their NAFLD grade. Furthermore, because of the failure to conduct independent biochemical assessment of the turmeric/curcumin product used in most studies as well as potential sources of bias, results should be interpreted with caution.

Curcumin/turmeric supplementation could improve blood pressure and endothelial function: A grade-assessed systematic review and dose-response meta-analysis of randomized controlled trials

BACKGROUND AND PURPOSE

A number of studies have examined the impact of curcumin/turmeric on blood pressure and the factors allegedly responsible for hypertension. In this systematic review and meta-analysis, we tried to sum up the existing literature on randomized controlled trials (RCTs) investigating this hypothesis.

METHODS

Online databases (PubMed, Scopus, Web of Science Core Collection, Cochrane Library, and Google Scholar) were searched from inception up to October 2022. We used the cochrane quality assessment tool to evaluate the risk of bias. Outcomes of interest included systolic blood pressure (SBP), diastolic blood pressure (DBP), blood levels of vascular cell adhesion molecule-1 (VCAM-1) and intracellular adhesion molecule-1 (ICAM-1), flow-mediated vasodilation (FMD), and pulse-wave velocity (PWV). Weighted mean differences (WMDs) were derived and reported. In case of significant between-study heterogeneity, subgroup analyses were carried out. Significance level was considered as P-values<0.05.

RESULTS

Finally, 35 RCTs out of 4182 studies were included. Our findings suggested that curcumin/turmeric supplementation significantly improved SBP (WMD: -2.02 mmHg; 95 % CI: -2.85, -1.18), DBP (WMD: -0.82 mmHg; 95 % CI: -1.46, -0.18), VCAM-1 (WMD: -39.19 ng/mL; 95 % CI: -66.15, -12.23), and FMD (WMD: 2.00 %; 95 % CI: 1.07, 2.94). However, it did not significantly change levels of ICAM-1 (WMD: -17.05 ng/ml; 95 % CI: -80.79, 46.70), or PWV (WMD: -79.53 cm/s; 95 % CI: -210.38, 51.33).

CONCLUSION

It seems that curcumin/turmeric supplementation could be regarded as a complementary method to improve blood pressure and endothelial function. However, further research is needed to clarify its impact on inflammatory adhesion molecules in the circulation.

Mechanisms Linking Metabolic-Associated Fatty Liver Disease (MAFLD) to Cardiovascular Disease

PURPOSE OF REVIEW

Metabolic-associated fatty liver disease (MAFLD) is a condition of fat accumulation in the liver that occurs in the majority of patients in combination with metabolic dysfunction in the form of overweight or obesity. In this review, we highlight the cardiovascular complications in MAFLD patients as well as some potential mechanisms linking MAFLD to the development of cardiovascular disease and highlight potential therapeutic approaches to treating cardiovascular diseases in patients with MAFLD.

RECENT FINDINGS

MAFLD is associated with an increased risk of cardiovascular diseases (CVD), including hypertension, atherosclerosis, cardiomyopathies, and chronic kidney disease. While clinical data have demonstrated the link between MAFLD and the increased risk of CVD development, the mechanisms responsible for this increased risk remain unknown. MAFLD can contribute to CVD through several mechanisms including its association with obesity and diabetes, increased levels of inflammation, and oxidative stress, as well as alterations in hepatic metabolites and hepatokines. Therapies to potentially treat MAFLD-induced include statins and lipid-lowering drugs, glucose-lowering agents, antihypertensive drugs, and antioxidant therapy.

The effect of curcumin supplementation on weight loss and anthropometric indices: an umbrella review and updated meta-analyses of randomized controlled trials

BACKGROUND

Curcumin supplementation may promote weight loss and ameliorate obesity-related complications through its antioxidative and anti-inflammatory properties.

OBJECTIVE

An umbrella review and updated meta-analysis of randomized controlled trials (RCTs) was conducted to evaluate the effect of curcumin supplementation on anthropometric indices.

METHODS

Systematic reviews and meta-analyses (SRMAs) of RCTs were identified from electronic databases (Medline, Scopus, Cochrane, and Google Scholar) up to 31 March, 2022, without language restriction. SRMAs were included if they assessed curcumin supplementation on any of the following: BMI, body weight (BW), or waist circumference (WC). Subgroup analyses were performed, stratifying by patient types, severity of obesity, and curcumin formula. The study protocol was a priori registered.

RESULTS

From an umbrella review, 14 SRMAs with 39 individual RCTs were included with a high degree of overlap. In addition, searching was updated from the last search of included SRMAs in April 2021 up to 31 March, 2022, and we found 11 additional RCTs, bringing the total up to 50 RCTs included in the updated meta-analyses. Of these, 21 RCTs were deemed of high risk of bias. Curcumin supplementation significantly reduced BMI, BW, and WC with mean differences (MDs) of -0.24 kg/m2 (95% CI: -0.32, -0.16 kg/m2), -0.59 kg (95% CI: -0.81, -0.36 kg), and -1.32 cm (95% CI: -1.95, -0.69 cm), respectively. The bioavailability-enhanced form reduced BMI, BWs, and WC more, with MDs of -0.26 kg/m2 (95% CI: -0.38, -0.13 kg/m2), -0.80 kg (95% CI: -1.38, -0.23 kg) and -1.41 cm (95% CI: -2.24, -0.58 cm), respectively. Significant effects were also seen in subgroups of patients, especially in adults with obesity and diabetes.

CONCLUSIONS

Curcumin supplementation significantly reduces anthropometric indices, and bioavailability-enhanced formulas are preferred. Augmenting curcumin supplement with lifestyle modification should be an option for weight reduction. This trial was registered at PROSPERO as CRD42022321112 (https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022321112).

Effects of curcumin/turmeric supplementation on obesity indices and adipokines in adults: A grade-assessed systematic review and dose-response meta-analysis of randomized controlled trials

In the present study, we explored the effect of curcumin/turmeric supplementation on anthropometric indices of obesity, leptin, and adiponectin. We searched PubMed, Scopus, Web of Science, Cochrane Library, and Google Scholar up to August 2022. Randomized clinical trials (RCTs) investigating the impact of curcumin/turmeric on obesity indices and adipokines were included. We applied the Cochrane quality assessment tool to evaluate the risk of bias. The registration number is CRD42022350946. Sixty eligible RCTs, with a total sample size of 3691 individuals were included for quantitative analysis. We found that supplementation with curcumin/turmeric significantly reduced body weight (WMD: -0.82 kg, 95% CI: -1.30, -0.35; p = 0.001), body mass index (WMD: -0.30 kg/m² , 95% CI: -0.53, -0.06, p = 0.013), waist circumference (WMD: -1.31 cm, 95% CI: -1.94, -0.69, p < 0.001), body fat percentage (WMD: -0.88%, 95% CI: -1.51, -0.25, p = 0.007), leptin (WMD = -4.46 ng/mL; 95% CI: -6.70, -2.21, p < 0.001), and increased adiponectin (WMD = 2.48 μg/mL; 95% CI: 1.34, 3.62, p < 0.001). Overall, our study shows that supplementation with curcumin/turmeric significantly improves anthropometric indices of obesity and adiposity-related adipokines (leptin and adiponectin). However, due to high between-studies heterogeneity, we should interpret the results with caution.

The sirtuin family in health and disease

Sirtuins (SIRTs) are nicotine adenine dinucleotide(+)-dependent histone deacetylases regulating critical signaling pathways in prokaryotes and eukaryotes, and are involved in numerous biological processes. Currently, seven mammalian homologs of yeast Sir2 named SIRT1 to SIRT7 have been identified. Increasing evidence has suggested the vital roles of seven members of the SIRT family in health and disease conditions. Notably, this protein family plays a variety of important roles in cellular biology such as inflammation, metabolism, oxidative stress, and apoptosis, etc., thus, it is considered a potential therapeutic target for different kinds of pathologies including cancer, cardiovascular disease, respiratory disease, and other conditions. Moreover, identification of SIRT modulators and exploring the functions of these different modulators have prompted increased efforts to discover new small molecules, which can modify SIRT activity. Furthermore, several randomized controlled trials have indicated that different interventions might affect the expression of SIRT protein in human samples, and supplementation of SIRT modulators might have diverse impact on physiological function in different participants. In this review, we introduce the history and structure of the SIRT protein family, discuss the molecular mechanisms and biological functions of seven members of the SIRT protein family, elaborate on the regulatory roles of SIRTs in human disease, summarize SIRT inhibitors and activators, and review related clinical studies.

Efficacy and safety of dietary polyphenol supplementation in the treatment of non-alcoholic fatty liver disease: A systematic review and meta-analysis

Background

Dietary polyphenol treatment of non-alcoholic fatty liver disease (NAFLD) is a novel direction, and the existing clinical studies have little effective evidence for its therapeutic effect, and some studies have inconsistent results. The effectiveness of dietary polyphenols in the treatment of NAFLD is still controversial. The aim of this study was to evaluate the therapeutic efficacy of oral dietary polyphenols in patients with NAFLD.

Methods

The literature (both Chinese and English) published before 30 April 2022 in PubMed, Cochrane, Medline, CNKI, and other databases on the treatment of NAFLD with dietary polyphenols was searched. Manual screening, quality assessment, and data extraction of search results were conducted strictly according to the inclusion and exclusion criteria. RevMan 5.3 software was used to perform the meta-analysis.

Results

The RCTs included in this study involved dietary supplementation with eight polyphenols (curcumin, resveratrol, naringenin, anthocyanin, hesperidin, catechin, silymarin, and genistein) and 2,173 participants. This systematic review and meta-analysis found that 1) curcumin may decrease body mass index (BMI), Aspartate aminotransferase (AST), Alanine aminotransferase (ALT), Triglycerides (TG) total cholesterol (TC), and Homeostasis Model Assessment-Insulin Resistance (HOMA-IR) compared to placebo; and curcumin does not increase the occurrence of adverse events. 2) Although the meta-analysis results of all randomized controlled trials (RCTs) did not reveal significant positive changes, individual RCTs showed meaningful results. 3) Naringenin significantly decreased the percentage of NAFLD grade, TG, TC, and low-density lipoprotein cholesterol (LDL-C) and increased high-density lipoprotein cholesterol (HDL-C) but had no significant effect on AST and ALT, and it is a safe supplementation. 4) Only one team presents a protocol about anthocyanin (from Cornus mas L. fruit extract) in the treatment of NAFLD. 5) Hesperidin may decrease BMI, AST, ALT, TG, TC, HOMA-IR, and so on. 6) Catechin may decrease BMI, HOMA-IR, and TG level, and it was well tolerated by the patients. 7) Silymarin was effective in improving ALT and AST and reducing hepatic fat accumulation and liver stiffness in NAFLD patients.

Conclusion

Based on current evidence, curcumin can reduce BMI, TG, TC, liver enzymes, and insulin resistance; catechin can reduce BMI, insulin resistance, and TG effectively; silymarin can reduce liver enzymes. For resveratrol, naringenin, anthocyanin, hesperidin, and catechin, more RCTs are needed to further evaluate their efficacy and safety.