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

Natural Compounds Exert Anti-Obesity Effects by Regulating Cytokines

Obesity, along with its associated health risks such as hypertension, hyperlipidemia, Type 2 diabetes, stroke, metabolic syndrome, asthma, and cancer, constitutes a significant global health burden, contributing substantially to morbidity and mortality. Cytokines, a group of secreted signaling proteins, are crucial in initiating, maintaining, and resolving immune and metabolic responses. Although cytokines have unique advantages in regulating immune and metabolic functions, their therapeutic application for obesity remains limited in clinical practice. Natural compounds, known for their structural diversity and low toxicity, have become a valuable resource for drug development. Many natural compounds have shown anti-obesity effects. This review comprehensively examines the mechanisms underlying obesity, with a specific focus on the roles of cytokines, such as inflammatory cytokines, adipokines, and growth factors. Additionally, it highlights the regulatory interactions between gut microbiota and cytokines in obesity. The review critically analyzes current anti-obesity pharmacological interventions and summarizes advanced methodologies for identifying potential natural compounds. Finally, it identifies promising natural compounds that modulate cytokine activity to prevent or treat obesity and assesses their potential as complementary or alternative therapies.

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.

Impact of exercise intervention with or without curcumin supplementation on body fat composition, glucose, and lipid metabolism in obese adults: A meta-analysis

This study was carried out to systematically review and evaluate the influence of exercise with and without curcumin on body fat composition, glucose, and lipid metabolism in obese adults. Search for eligible studies through four databases, and then proceed with screening. The inclusion criteria are as follows: (1) obese adults; (2) randomized controlled trial (RCT); (3) classified the exercise intervention with curcumin supplementation as the exercise with curcumin (CU) group and without curcumin supplementation as the exercise without curcumin (EX) group; (4) Conducted pre- and post-training assessments, which include body fat composition, glucose and lipid metabolism parameters. Use the Cochrane bias risk assessment tool to evaluate the quality of the selected study. Select standardized mean difference (SMD) as the appropriate effect scale index, and use Revman 5.4 software to analyze the mean difference of the selected article data with a 95% confidence interval (CI). A total of seven studies fulfilled the inclusion criteria and were selected for the meta-analysis. The included studies involved 72 males and 111 females, where 94 belonged to the EX group and 89 from the CU group. The CU group benefited more from the reduced Fat% (SMD, 2.18 [0.12, 4.24], p < 0.05, I2 = 0%, p for heterogeneity = 0.98) than the EX group. The study demonstrated that the combined exercise intervention with curcumin supplementation significantly reduced Fat% in obese adults compared with exercise without supplementing curcumin.

Effects of nanocurcumin supplementation on metabolic syndrome: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Metabolic syndrome (MetS) encompasses metabolic risk factors like elevated blood glucose, abnormal lipid levels, and hypertension. Nanocurcumin, a nanoscale formulation of curcumin, may offer therapeutic benefits for MetS management. This systematic review and meta-analysis evaluates the impact of nanocurcumin supplementation on key MetS parameters.

METHODS

A systematic literature search identified 20 randomized controlled trials (RCTs) with 1394 participants. Data were pooled using a random-effects model, and standardized mean differences (SMDs) were calculated for key outcomes.

RESULTS

Nanocurcumin supplementation significantly improved waist circumference (WC) (standardized mean difference (SMD): -0.30 cm), fasting blood sugar (FBS) (SMD: -0.34 mg/dL), HbA1c (SMD: -0.33 %), and quantitative insulin sensitivity check index (QUICKI) score (SMD: 0.73). Lipid profile parameters, including total cholesterol (SMD: -0.18 mg/dL), LDL-C (SMD: -0.16 mg/dL), and HDL-C (SMD: 0.32 mg/dL), also reduced significantly. Improvement in diastolic blood pressure (DBP) (SMD: -0.32 mmHg), total antioxidant capacity (TAC) (SMD: 0.44 mmol/L), malondialdehyde (MDA) (SMD: -0.37 mmol/L), tumor necrosis factor-α (TNF-α) (SMD: -2.30 ng/L), interleukin-6 (IL-6) (SMD: -1.07 ng/L), and high-sensitivity C-reactive protein (hs-CRP) (SMD: -0.34 mg/L) were observed.

CONCLUSION

Nanocurcumin supplementation significantly improves multiple MetS-related parameters, including anthropometric measures, glycemic control, lipid profile, blood pressure, oxidative stress markers, and inflammatory biomarkers. These findings highlight nanocurcumin's potential as an effective adjunctive therapy for managing MetS. However, the variability in study participant ages, treatment durations, and sample sizes suggests the need for further well-designed RCTs to establish optimal usage guidelines.

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.

Plant-Derived Substances for Prevention of Necrotising Enterocolitis: A Systematic Review of Animal Studies

Inflammation, oxidative injury, and gut dysbiosis play an important role in the pathogenesis of necrotising enterocolitis (NEC). Plant-derived substances have historically been used as therapeutic agents due to their anti-inflammatory, antioxidant, and antimicrobial properties. We aimed to review pre-clinical evidence for plant-derived substances in the prevention and treatment of NEC. A systematic review was conducted using the following databases: PubMed, EMBASE, EMCARE, MEDLINE and Cochrane Library (PROSPERO CRD42022365477). Randomized controlled trials (RCTs) and quasi-RCTs that evaluated a plant-derived substance as an intervention for NEC in an animal model of the illness and compared pre-stated outcomes (e.g., clinical severity, severity of intestinal injury, mortality, laboratory markers of inflammation and oxidative injury) were included. Sixteen studies (n = 610) were included in the systematic review. Ten of the sixteen included RCTs (Preterm rat pups: 15, Mice: 1) reported mortality and all reported NEC-related histology. Meta-analysis showed decreased mortality [12/134 vs. 27/135; RR: 0.48 (95% CI: 0.26 to 0.87); p = 0.02, 10 RCTs] and decreased NEC in the experimental group [24/126 vs. 55/79; RR: 0.34 (95% CI: 0.22 to 0.52); p < 0.001, 6 RCTs]. Markers of inflammation (n = 11) and oxidative stress (n = 13) improved in all the studies that have reported this outcome. There was no significant publication bias for the outcome of mortality. Plant-derived substances have the potential to reduce the incidence and severity of histologically diagnosed NEC and mortality in rodent models. These findings are helpful in guiding further pre-clinical studies towards developing a food supplement for the prevention of NEC in preterm infants.

Inflammatory and Metabolic Biomarker Assessment in a Randomized Presurgical Trial of Curcumin and Anthocyanin Supplements in Patients with Colorectal Adenomas

Colorectal cancer prevention is crucial for public health, given its high mortality rates, particularly in young adults. The early detection and treatment of precancerous lesions is key to preventing carcinogenesis progression. Natural compounds like curcumin and anthocyanins show promise in impeding adenomatous polyp progression in preclinical models. We conducted a randomized, double-blind, placebo-controlled, phase II presurgical trial in 35 patients with adenomatous polyps to explore the biological effects of curcumin and anthocyanins on circulating biomarkers of inflammation and metabolism. No significant difference in biomarker changes by treatment arm was observed. However, the network analysis before treatment revealed inverse correlations between adiponectin and BMI and glycemia, as well as direct links between inflammatory biomarkers and leptin and BMI. In addition, a considerable inverse relationship between adiponectin and grade of dysplasia was detected after treatment (corr = -0.45). Finally, a significant increase in IL-6 at the end of treatment in subjects with high-grade dysplasia was also observed (p = 0.02). The combined treatment of anthocyanins and curcumin did not result in the direct modulation of circulating biomarkers of inflammation and metabolism, but revealed a complex modulation of inflammatory and metabolic biomarkers of colon carcinogenesis.

Cell Survival, Death, and Proliferation in Senescent and Cancer Cells: the Role of (Poly)phenols

Cellular senescence has long been considered a permanent state of cell cycle arrest occurring in proliferating cells subject to different stressors, used as a cellular defense mechanism from acquiring potentially harmful genetic faults. However, recent studies highlight that senescent cells might also alter the local tissue environment and concur to chronic inflammation and cancer risk by secreting inflammatory and matrix remodeling factors, acquiring a senescence-associated secretory phenotype (SASP). Indeed, during aging and age-related diseases, senescent cells amass in mammalian tissues, likely contributing to the inevitable loss of tissue function as we age. Cellular senescence has thus become one potential target to tackle age-associated diseases as well as cancer development. One important aspect characterizing senescent cells is their telomere length. Telomeres shorten as a consequence of multiple cellular replications, gradually leading to permanent cell cycle arrest, known as replicative senescence. Interestingly, in the large majority of cancer cells, a senescence escape strategy is used and telomere length is maintained by telomerase, thus favoring cancer initiation and tumor survival. There is growing evidence showing how (poly)phenols can impact telomere maintenance through different molecular mechanisms depending on dose and cell phenotypes. Although normally, (poly)phenols maintain telomere length and support telomerase activity, in cancer cells this activity is negatively modulated, thus accelerating telomere attrition and promoting cancer cell death. Some (poly)phenols have also been shown to exert senolytic activity, thus suggesting both antiaging (directly eliminating senescent cells) and anticancer (indirectly, via SASP inhibition) potentials. In this review, we analyze selective (poly)phenol mechanisms in senescent and cancer cells to discriminate between in vitro and in vivo evidence and human applications considering (poly)phenol bioavailability, the influence of the gut microbiota, and their dose-response effects.

Effects of dietary polyphenol curcumin supplementation on metabolic, inflammatory, and oxidative stress indices in patients with metabolic syndrome: a systematic review and meta-analysis of randomized controlled trials

Objective

The aim was to conduct a systematic review and meta-analysis for assessing the effectiveness and safety of dietary polyphenol curcumin supplement on metabolic, inflammatory, and oxidative stress indices in patients with metabolic syndrome (MetS).

Methods

A comprehensive search for clinical trials was conducted in the following scientific databases: PubMed, SCOPUS, Cochrane Library, EMBASE, Web of Science, and China Biological Medicine. Randomized controlled trials (RCTs) evaluating the efficacy and safety of curcumin supplement for MetS were identified. A random-effects meta-analysis was performed using inverse variance, and efficacy was expressed as mean difference (MD) with 95% confidence interval (CI). The metabolic syndrome markers that were evaluated in the present study included waist circumference (WC), fasting blood sugar (FBS), systolic blood pressure (SBP), diastolic blood pressure (DBP), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), tumor necrosis factor-a (TNF-a), interleukin 6 (IL-6), C-reactive protein (CRP), ultrasensitive c-reactive protein (hsCRP), and malondialdehyde (MDA). By employing the Cochrane tool, RCTs were assessed for bias risk.

Results

A total of 785 participants from 13 RCTs were included, with intervention durations ranging from 4 to 12 weeks. Compared with the control group, the curcumin group had positive effects on WC (MD = -2.16, 95% CI: -3.78 to -0.54, p = 0.009, seven studies), FBS (MD = -8.6, 95% CI: -15.45 to -1.75, p = 0.01, nine studies), DBP (MD = -2.8, 95% CI: -4.53 to - 1.06, p = 0.002, five studies), HDL-C (MD = 4.98, 95% CI: 2.58 to 7.38, p < 0.0001, eight studies), TNF-a (MD = -12.97, 95% CI: -18.37 to -7.57, p < 0.00001, two studies), CRP (MD = - 1.24, 95% CI: -1.71 to -0.77, p < 0.00001, two studies), and MDA (MD = -2.35, 95% CI: -4.47 to -0.24, p = 0.03, three studies). These improvements were statistically significant. Meanwhile, there was no significant improvement in SBP (MD = -4.82, 95% CI: -9.98 to 0.35, p = 0.07, six studies), TG (MD = 1.28, 95% CI: -3.75 to 6.30, p = 0.62, eight studies), IL-6 (MD = -1.5, 95% CI: -3.97 to 0.97, p = 0.23, two studies), or hsCRP (MD = -1.10, 95% CI: -4.35 to 2.16, p < 0.51, two studies). FBS, SBP, HDL-C, IL-6, CRP, hsCRP, and MDA had a relatively high heterogeneity.

Conclusion

Curcumin exhibited promising potential in enhancing markers associated with metabolic syndrome, including inflammation. However, additional studies are required to confirm such findings since the included evidence is limited and has a relatively high heterogeneity.

Systematic review registration

https://www.crd.york.ac.uk/prospero, identifier CRD42022362553.