Modulation of gut microbiota contributes to curcumin-mediated attenuation of hepatic steatosis in rats

Curcumin exerts anti-tumor activity in colorectal cancer via gut microbiota-mediated CD8+ T Cell tumor infiltration and ferroptosis

Colorectal cancer (CRC), as a high-incidence malignancy, continues to present significant challenges in prevention, screening, and treatment. Curcumin (Cur) exhibits notable anti-inflammatory and anticancer properties. Despite its poor solubility in water and low bioavailability, high concentrations of Cur are detected in the gastrointestinal tract after oral administration, suggesting that it may directly interact with the gut microbiota and exert regulatory effects. This study aims to explore the mechanisms by which Cur improves CRC by modulating gut microbiota. Firstly, we evaluated the effect of Cur on CRC cell viability in vitro using the MTT assay, and the results showed a significant inhibitory effect on CRC cell growth. The IC50 values for Cur in CT26 and RKO cells were 23.52 μM, 16.11 μM, and 13.62 μM at 24, 48, and 72 hours, respectively, and 26.3 μM, 16.52 μM, and 14.22 μM at 24, 48, and 72 hours, respectively. Cur induced apoptosis and caused G2 phase cell cycle arrest in tumor cells. Subsequently, we established a CRC mouse model. Oral administration of Cur at 15 mg kg-1 and 30 mg kg-1 inhibited CRC progression, as evidenced by reduced tumor volume, histological analysis, immunohistochemistry, and an increased number of CD8+ T cells infiltrating the tumors. Ferroptosis in tumor cells was also observed. Cur partially restored the gut microbiota of CRC mice, altering the abundance and diversity of the gut microbiota and affecting serum metabolite distribution, with significant increases in the abundance of SCFA-producing microbes such as Lactobacillus and Kineothrix. To verify causality, we designed a fecal microbiota transplantation (FMT) experiment. Compared with CRC mice, the fecal microbiota from Cur-treated mice significantly alleviated CRC symptoms, including slowed tumor growth, enhanced CD8+ T cell tumor infiltration, and induced ferroptosis in tumor cells. Additionally, when gut microbiota was depleted with antibiotics, Cur's antitumor effects disappeared, suggesting that Cur mitigates CRC in a gut microbiota-dependent manner. These findings provide new insights into the mechanisms underlying CRC and propose novel therapeutic interventions, emphasizing the interaction between gut microbiota and immune responses within the tumor immune microenvironment (TIME).

Progress in the study of curcumin metabolism in vivo

Curcumin has diverse biological functions, especially antioxidant and anti-inflammatory properties, but clinical trials have been hindered by its low bioavailability and pharmacokinetic properties. To achieve therapeutic efficacy, understanding curcumin's in vivo metabolism is crucial. We reviewed current research on curcumin metabolism in PubMed, Google Scholar, and CNKI. This article outlines curcumin's metabolic processes in the body via oral and intravenous injection. It suggests that upon entering the human body, curcumin may undergo oxidation, reduction, binding, and microbial community influence.

Gut Microbiota and Metabolic Dysfunction-Associated Steatotic Liver Disease

Background: The gut microbiota constitutes a complex microorganism community that harbors bacteria, viruses, fungi, protozoa, and archaea. The human gut bacterial microbiota has been extensively proven to participate in human metabolism, immunity, and nutrient absorption. Its imbalance, namely "dysbiosis", has been linked to disordered metabolism. Metabolic dysfunction-associated steatotic liver disease (MASLD) is one of the features of deranged human metabolism and is the leading cause of liver cirrhosis and hepatocellular carcinoma. Thus, there is a pathophysiological link between gut dysbiosis and MASLD. Aims and Methods: We aimed to review the literature data on the composition of the human bacterial gut microbiota and its dysbiosis in MASLD and describe the concept of the "gut-liver axis". Moreover, we reviewed the approaches for gut microbiota modulation in MASLD treatment. Results: There is consolidated evidence of particular gut dysbiosis associated with MASLD and its stages. The model explaining the relationship between gut microbiota and the liver has a bidirectional organization, explaining the physiopathology of MASLD. Oxidative stress is one of the keystones in the pathophysiology of MASLD and fibrosis generation. There is promising and consolidated evidence for the efficacy of pre- and probiotics in reversing gut dysbiosis in MASLD patients, with therapeutic effects. Few yet encouraging data on fecal microbiota transplantation (FMT) in MASLD are available in the literature. Conclusions: The gut dysbiosis characteristic of MASLD is a key target in its reversal and treatment via diet, pre/probiotics, and FMT treatment. Oxidative stress modulation remains a promising target for MASLD treatment, prevention, and reversal.

Biocompatible Poly(ε-Caprolactone) Nanocapsules Enhance the Bioavailability, Antibacterial, and Immunomodulatory Activities of Curcumin

Curcumin (Cur), the primary curcuminoid found in Curcuma longa L., has garnered significant attention for its potential anti-inflammatory and antibacterial properties. However, its hydrophobic nature significantly limits its bioavailability. Additionally, adipose-derived stem cells (ADSCs) possess immunomodulatory properties, making them useful for treating inflammatory and autoimmune conditions. This study aims to verify the efficacy of poly(ε-caprolactone) nanocapsules (NCs) in improving Cur's bioavailability, antibacterial, and immunomodulatory activities. The Cur-loaded nanocapsules (Cur-NCs) were characterized for their physicochemical properties (particle size, polydispersity index, Zeta potential, and encapsulation efficiency) and stability over time. A digestion test simulated the behavior of Cur-NCs in the gastrointestinal tract. Micellar phase analyses evaluated the Cur-NCs' bioaccessibility. The antibacterial activity of free Cur, NCs, and Cur-NCs against various Gram-positive and Gram-negative strains was determined using the microdilution method. ADSC viability, treated with Cur-NCs and Cur-NCs in the presence or absence of lipopolysaccharide, was analyzed using the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide assay. Additionally, ADSC survival was assessed through the Muse apoptotic assay. The expression of both pro-inflammatory (interleukin-1β and tumor necrosis factor-α) and anti-inflammatory (IL-10 and transforming growth factor-β) cytokines on ADSCs was evaluated by real-time polymerase chain reaction. The results demonstrated high stability post-gastric digestion of Cur-NCs and elevated bioaccessibility of Cur post-intestinal digestion. Moreover, Cur-NCs exhibited antibacterial activity against Escherichia coli without affecting Lactobacillus growth. No significant changes in the viability and survival of ADSCs were observed under the experimental conditions. Finally, Cur-NCs modulated the expression of both pro- and anti-inflammatory cytokines in ADSCs exposed to inflammatory stimuli. Collectively, these findings highlight the potential of Cur-NCs to enhance Cur's bioavailability and therapeutic efficacy, particularly in cell-based treatments for inflammatory diseases and intestinal dysbiosis.

Common Mitochondrial Targets of Curcumin and Cinnamic Acid, the Membrane-Active Natural Phenolic Compounds

Background: Research has shown the multiple actions of curcumin on different cell systems, including enzymes and mitochondria. The detected effects of curcumin on mitochondria are diverse, ranging from protective to toxic. Objectives: In this present work, the influence of curcumin, as well as cinnamic acid, which is a microbial metabolite and a possible product of the microbial breakdown of curcumin, on isolated mitochondria, was investigated. Methods: Membrane potential, swelling, respiration, and calcium retention capacity were studied using selective electrodes, fluorescence and spectral methods. Results: It was found that curcumin at low concentrations (10-20 μM) activated the opening of the calcium-dependent permeability transition pore (mPTP) and decreased the calcium retention capacity and threshold concentrations necessary for the mPTP opening. Moreover, curcumin caused a concentration-dependent stepwise decrease in the membrane potential, accompanied by the activation of respiration and a decrease in oxidative phosphorylation, which indicates that curcumin is a typical mitochondrial uncoupler. The uncoupling effect strongly depended on the concentration of curcumin, which also increased, stepwise, from weak uncoupling at 25 µM to complete uncoupling at 75-100 µM. Cinnamic acid had similar effects, with the exception of the depolarizing effect, at concentrations that were an order of magnitude higher. Conclusions: Presumably, the uncoupling action of curcumin is a priming event that modulates any energy- and redox-dependent mitochondrial functions, from positive stimulation to toxic disorder. This effect can also underlie the curcumin-induced changes in different cellular processes and be achieved by targeted delivery of curcumin to certain cells, bypassing the microbiota.

Curcumin suppresses colorectal tumorigenesis through restoring the gut microbiota and metabolites

BACKGROUND

Curcumin has been reported to have activity for prevention and therapy of CRC, yet its underlying mechanisms remain largely unknown. Recently, emerging evidence suggests that the gut microbiota and its metabolites contribute to the causation and progression of Colorectal cancer (CRC). In this study, we aimed to investigate if curcumin affects the tumorigenesis of CRC by modulating gut microbiota and its metabolites.

METHODS

Forty male C57BL/6JGpt mice were randomly divided into four groups: negative control (NC), curcumin control, CRC model, and curcumin treatment (CRC-Cur) groups. CRC mouse model was induced by using azoxymethane (AOM) and dextran sodium sulfate (DSS), and the mice in CRC model and curcumin treatment groups received oral PBS or curcumin (150 mg/kg/day), respectively. Additionally, fecal samples were collected. 16 S rRNA sequencing and Liquid Chromatography Mass Spectrometry (LC-MS)-based untargeted metabolomics were used to observe the changes of intestinal flora and intestinal metabolites.

RESULTS

Curcumin treatment restored colon length and structural morphology, and significantly inhibited tumor formation in AOM/DSS-induced CRC model mice. The 16S rRNA sequencing analysis indicated that the diversity and richness of core and total species of intestinal microflora in the CRC group were significantly lower than those in the NC group, which were substantially restored in the curcumin treatment group. Curcumin reduced harmful bacteria, including Ileibacterium, Monoglobus and Desulfovibrio, which were elevated in CRC model mice. Moreover, curcumin increased the abundance of Clostridia_UCG-014, Bifidobacterium and Lactobacillus, which were decreased in CRC model mice. In addition, 13 different metabolites were identified. Compared to the NC group, ethosuximide, xanthosine, and 17-beta-estradiol 3-sulfate-17-(beta-D-glucuronide) were elevated in the CRC model group, whereas curcumin treatment significantly reduced their levels. Conversely, glutamylleucine, gamma-Glutamylleucine, liquiritin, ubenimex, 5'-deoxy-5'-fluorouridine, 7,8-Dihydropteroic acid, neobyakangelicol, libenzapril, xenognosin A, and 7,4'-dihydroxy-8-methylflavan were decreased in the CRC group but notably upregulated by curcumin. Kyoto Encyclopedia of Genes and Genome (KEGG) pathway analysis revealed enrichment in seven pathways, including folate biosynthesis (P < 0.05).

CONCLUSIONS

The gut microecological balance was disrupted in AOM/DSS-induced CRC mice, accompanied by metabolite dysbiosis. Curcumin restored the equilibrium of the microbiota and regulated metabolites, highly indicating that curcumin may alleviate the development of AOM/DSS induced colorectal cancer in mice by regulating intestinal flora homeostasis and intestinal metabolites.

Dietary Polyphenols and Gut Microbiota Cross-Talk: Molecular and Therapeutic Perspectives for Cardiometabolic Disease: A Narrative Review

The intricate interplay between the gut microbiota and polyphenols has emerged as a captivating frontier in understanding and potentially harnessing the therapeutic potential of these bioactive compounds. Phenolic compounds, renowned for their antioxidant, anti-inflammatory, antidiabetic, and anticancer properties, are subject to intricate transformations within the gut milieu, where the diverse microbial ecosystem exerts profound effects on their metabolism and bioavailability. Conversely, polyphenols exhibit a remarkable capacity to modulate the composition and activity of the gut microbiota, fostering a bidirectional relationship that extends beyond mere nutrient processing. This symbiotic interaction holds significant implications for human health, particularly in cardiometabolic diseases such as diabetes mellitus, metabolic-dysfunction-associated steatotic liver disease, and cardiovascular disease. Through a comprehensive exploration of molecular interactions, this narrative review elucidates the reciprocal dynamics between the gut microbiota and polyphenols, unveiling novel avenues for therapeutic intervention in cardiometabolic disorders. By unravelling the intricate cross-talk between these two entities, this review underscores the multifaceted roles of polyphenols in overall health and the pivotal role of gut microbiota modulation as a promising therapeutic strategy in mitigating the burden of cardiometabolic diseases.

Polyphenols improve non-alcoholic fatty liver disease via gut microbiota: A comprehensive review

Polyphenols, natural micronutrients derived from plants, are valued for their anti-inflammatory and antioxidant properties. The escalating global prevalence of non-alcoholic fatty liver disease (NAFLD) underscores its status as a chronic progressive liver condition. Furthermore, the dysregulation of gut microbiota (GM) is implicated in the onset and progression of NAFLD through the actions of metabolites such as bile acids (BAs), lipopolysaccharide (LPS), choline, and short-chain fatty acids (SCFAs). Additionally, GM may influence the integrity of the intestinal barrier. This review aims to evaluate the potential effects of polyphenols on GM and intestinal barrier function, and their subsequent impact on NAFLD. We searched through a wide range of databases, such as Web of Science, PubMed, EMBASE, and Scopus to gather information for our non-systematic review of English literature. GM functions and composition can be regulated by polyphenols such as chlorogenic acid, curcumin, green tea catechins, naringenin, quercetin, resveratrol, and sulforaphane. Regulating GM composition improves NAFLD by alleviating inflammation, liver fat accumulation, and liver enzymes. Furthermore, it improves serum lipid profile and gut barrier integrity. All of these components affect NAFLD through the metabolites of GM, including SCFAs, choline, LPS, and BAs. Current evidence indicates that chlorogenic acid, resveratrol, quercetin, and curcumin can modulate GM, improving intestinal barrier integrity and positively impacting NAFLD. More studies are necessary to evaluate the safety and efficacy of naringenin, sulforaphane, and catechin.

Curcumin and Gut Microbiota: A Narrative Overview with Focus on Glycemic Control

Turmeric is a spice widely used in China, Southeast Asia, and in traditional Ayurvedic medicine. Its safety profile and efficacy as an antioxidant, anti-inflammatory, antimicrobial, antitumor, antidiabetic, and anti-obesity agent have led to extensive research into its potential role in preventing and treating metabolic diseases. The active compound in turmeric is curcumin, which exhibits low systemic bioavailability after oral administration. However, it is detectable in the gut, where it bidirectionally interacts with the gut microbiota (GM), which plays a crucial role in maintaining host health. The favorable effects of curcumin, particularly its hypoglycemic properties, are linked to alteration in intestinal dysbiosis observed in type 2 diabetes mellitus and metabolic syndrome patients. Restoration of the eubiotic GM may contribute to glycemic homeostasis. Preclinical and clinical studies have demonstrated the involvement of the GM in the regulation of glucose and lipid metabolism. Although the underlying mechanism remains incompletely understood, intestinal dysbiosis is associated with insulin resistance, hyperglycemia, and low-grade inflammation. In the present overview, we summarize the biological properties of curcumin, focusing on its link with GM and, therefore, on its potential role in metabolic diseases.

Curcumin supplementation alleviates hepatic fat content associated with modulation of gut microbiota-dependent bile acid metabolism in patients with nonalcoholic simple fatty liver disease: a randomized controlled trial

BACKGROUND

Our previous studies showed that curcumin prevented hepatic steatosis in animal models.

OBJECTIVES

This study aimed to assess the effects of curcumin on hepatic fat content, body composition, and gut microbiota-dependent bile acid (BA) metabolism in patients with nonalcoholic simple fatty liver (NASFL).

METHODS

In a 24-wk double-blind randomized trial, 80 patients with NASFL received 500 mg/d curcumin or placebo. Hepatic fat content was measured using FibroTouch-based controlled attenuation parameters (CAPs). Microbial composition and BA metabolites were analyzed using 16S rRNA sequencing and metabolomics.

RESULTS

Curcumin consumption significantly reduced CAP value compared with placebo (-17.5 dB/m; 95% confidence interval [CI]: -27.1, -7.8 dB/m; P < 0.001). This corresponded to reduction in weight (-2.6 kg; 95% CI: -4.4, -0.8 kg; P < 0.001) and BMI (-1.0 kg/m2; 95% CI: -2.0, -0.1 kg/m2; P = 0.032) compared with placebo group. Additionally, free fatty acid (-0.12 mmol/L; 95% CI: -0.20, -0.04 mmol/L; P = 0.004), triglycerides (-0.29 mmol/L; 95% CI: -0.41, -0.14 mmol/L; P < 0.001), fasting blood glucose (-0.06 mmol/L; 95% CI: -0.12, -0.01 mmol/L; P = 0.038), hemoglobin A1c (-0.06%; 95% CI: -0.33, -0.01%; P = 0.019), and insulin (-4.94 μU/L; 95% CI: -9.73, -0.15 μU/L; P = 0.043) showed significant reductions in the curcumin group compared with placebo group. Gut microbiota analysis indicated that curcumin significantly decreased Firmicutes to Bacteroidetes ratio and significantly increased Bacteroides abundance. Serum levels of deoxycholic acid, the most potent activator of Takeda G protein-coupled receptor 5 (TGR5), were significantly elevated after curcumin intervention (37.5 ng/mL; 95% CI: 6.7, 68.4 ng/mL; P = 0.018). Curcumin treatment also increased TGR5 expression in peripheral blood mononuclear cells and serum glucagon-like peptide-1 levels (0.73 ng/mL; 95% CI: 0.16, 1.30 ng/mL; P = 0.012).

CONCLUSIONS

Improvements in gut microbiota-dependent BA metabolism and TGR5 activation after 24-wk curcumin intervention were associated with a reduction in hepatic fat content in patients with NASFL, providing evidence that curcumin is a potential nutritional therapy for NASFL. The trial was registered at www.chictr.org.cn as ChiCTR2200058052.

The Possible Synergistic Pharmacological Effect of an Oral Berberine (BBR) and Curcumin (CUR) Complementary Therapy Alleviates Symptoms of Irritable Bowel Syndrome (IBS): Results from a Real-Life, Routine Clinical Practice Settings-Based Study

Irritable bowel syndrome (IBS) is a prevalent chronic functional gastrointestinal disorder, characterised by recurrent abdominal discomfort and altered bowel movements. IBS cause a significantly negative impact on quality of life (QoL). Growing pharmacological evidence suggests that berberine (BBR) and curcumin (CUR) may mitigate IBS symptoms through multiple complementary synergistic mechanisms, resulting in the attenuation of intestinal inflammation and regulation of bowel motility and gut functions. In the present observational study conducted under real-life routine clinical practice settings, 146 patients diagnosed with IBS were enrolled by general practitioner clinics and pharmacies in Belgium. For the first time, this study assessed the potential synergistic pharmacological effect of a combined oral BBR/CUR supplement (Enterofytol® PLUS, containing 200 mg BBR and 49 mg CUR) (two tablets daily for 2 months), serving as complementary therapy in the management of IBS. Following the 2-month supplementation, significant improvements were observed in the patients' IBS severity index (IBSSI) (47.5%) and all the primary IBS symptoms, such as abdominal discomfort (47.2%), distension (48.0%), intestinal transit (46.8%), and QoL (48.1%) (all p < 0.0001). The improvement in the patients' IBSSI was independent of age, sex, and IBS sub-types. The patients' weekly maximum stool passage frequency decreased significantly (p < 0.0001), and the stool status normalized (p < 0.0001). The patients' need for concomitant conventional IBS treatment decreased notably: antispasmodics by 64.0% and antidiarrhoeals by 64.6%. Minor adverse effects were reported by a small proportion (7.1%) of patients, mostly gastrointestinal. The majority (93.1%) experienced symptom improvement or resolution, with a high satisfaction rate (82.6%) and willingness to continue the supplementation (79.0%). These findings support the potential synergistic pharmacological role of BBR and CUR in IBS, and their co-supplementation may alleviate IBS symptoms and improve QoL.

Stability and programmed sequential release of Lactobacillus plantarum and curcumin encapsulated in bilayer-stabilized W1/O/W2 double emulsion: Effect of pectin as protective shell

In order to overcome the problem that traditional W1/O/W2 double emulsions do not have targeted release performance, thereby better meeting the health needs of consumers, ovalbumin fibrils/pectin-based bilayer-stabilized double emulsion (OP-BDE) co-encapsulated with Lactobacillus plantarum and curcumin was constructed with pectin as the outer protective shell, which was expected to be used in the development of novel functional foods. The effects of pectin coating on the viability of Lactobacillus plantarum under conditions including storage, pasteurization, freeze-thaw cycles and in vitro simulated digestion were investigated. Results showed that pectin as protective shell could significantly enhance the tolerance of Lactobacillus plantarum to various environmental factors. Besides, the adsorption of pectin endowed OP-BDE with higher lipolysis and stronger protective effect on curcumin, remarkably improving the photostability and bioaccessibility of curcumin. In addition, in vitro simulated gastrointestinal release study indicated that OP-BDE possessed programmed sequential release property, allowing curcumin and Lactobacillus plantarum to be released in small intestine and colon, respectively. OP-BDE is the first reported co-delivery emulsion system with programmed release characteristic. This study provides new insights into OP-BDE in constructing co-delivery systems and programmed sequential release of active substances, and has potential reference and application value in actual food production.

Regulation Mechanism and Potential Value of Active Substances in Spices in Alcohol-Liver-Intestine Axis Health

Excessive alcohol intake will aggravate the health risk between the liver and intestine and affect the multi-directional information exchange of metabolites between host cells and microbial communities. Because of the side effects of clinical drugs, people tend to explore the intervention value of natural drugs on diseases. As a flavor substance, spices have been proven to have medicinal value, but they are still rare in treating hepatointestinal diseases caused by alcohol. This paper summarized the metabolic transformation of alcohol in the liver and intestine and summarized the potential value of various perfume active substances in improving liver and intestine diseases caused by alcohol. It is also found that bioactive substances in spices can exert antioxidant activity in the liver and intestine environment and reduce the oxidative stress caused by diseases. These substances can interfere with fatty acid synthesis, promote sugar and lipid metabolism, and reduce liver injury caused by steatosis. They can effectively regulate the balance of intestinal flora, promote the production of SCFAs, and restore the intestinal microenvironment.

Enhancing the Bioavailability and Bioactivity of Curcumin for Disease Prevention and Treatment

Curcumin, a natural polyphenolic component from Curcuma longa roots, is the main bioactive component of turmeric spice and has gained increasing interest due to its proposed anti-cancer, anti-obesity, anti-inflammatory, antioxidant, and lipid-lowering effects, in addition to its thermogenic capacity. While intake from dietary sources such as curry may be sufficient to affect the intestinal microbiome and thus may act indirectly, intact curcumin in the body may be too low (<1 microM) and not sufficient to affect signaling and gene expression, as observed in vitro with cultured cells (10-20 microM). Several strategies can be envisioned to increase curcumin levels in the body, such as decreasing its metabolism or increasing absorption through the formation of nanoparticles. However, since high curcumin levels could also lead to undesired regulatory effects on cellular signaling and gene expression, such studies may need to be carefully monitored. Here, we review the bioavailability of curcumin and to what extent increasing curcumin levels using nanoformulations may increase the bioavailability and bioactivity of curcumin and its metabolites. This enhancement could potentially amplify the disease-preventing effects of curcumin, often by leveraging its robust antioxidant properties.

Local and Systemic Effects of Bioactive Food Ingredients: Is There a Role for Functional Foods to Prime the Gut for Resilience?

Scientific advancements in understanding the impact of bioactive components in foods on the gut microbiota and wider physiology create opportunities for designing targeted functional foods. The selection of bioactive ingredients with potential local or systemic effects holds promise for influencing overall well-being. An abundance of studies demonstrate that gut microbiota show compositional changes that correlate age and disease. However, navigating this field, especially for non-experts, remains challenging, given the abundance of bioactive ingredients with varying levels of scientific substantiation. This narrative review addresses the current knowledge on the potential impact of the gut microbiota on host health, emphasizing gut microbiota resilience. It explores evidence related to the extensive gut health benefits of popular dietary components and bioactive ingredients, such as phytochemicals, fermented greens, fibres, prebiotics, probiotics, and postbiotics. Importantly, this review distinguishes between the potential local and systemic effects of both popular and emerging ingredients. Additionally, it highlights how dietary hormesis promotes gut microbiota resilience, fostering better adaptation to stress-a hallmark of health. By integrating examples of bioactives, this review provides insights to guide the design of evidence-based functional foods aimed at priming the gut for resilience.

Evaluation of curcumin nanoemulsion effect to prevent intestinal damage

Curcumin has gained great prominence for the prevention and treatment of inflammatory bowel disease. However, studies have reported the low bioavailability of orally administered curcumin. This work aimed to evaluate the characteristics, stability and effects of a curcumin-carrying nanoemulsion in preventing intestinal damage induced by indomethacin. Nanoemulsions containing curcumin were prepared by spontaneous emulsification method and it was characterized by dynamic light scattering (DLS), zeta potential and the morphology was evaluated by scanning electron microscopy (SEM). Its stability was tested under different conditions of pH, temperature at 0, 7, 14, 21 and 28 days. In animal experimentation, 36 male mice of the Mus musculus lineage (C57BL/6) were used. The intestinal inflammation was evaluated based on macroscopic, histopathological and metagenomic analysis. It was found a stable nanoemulsion with a size of 409.8 nm, polydispersion index (PDI) of 0.132 and zeta potential of -18.8 mV. However, these lost charge in pH2, showing instability in acidic media (p < 0.05). In animal experiments, the nanoemulsion did not significantly improve intestinal inflammation. However, the group treated with curcumin nanoemulsion showed a higher relative abundance of the genus Lactobacillus (p < 0.05). In conclusion, the curcumin nanoemulsion was relevant in the modulation of the intestinal microbiota.

Targeted therapies of curcumin focus on its therapeutic benefits in cancers and human health: Molecular signaling pathway-based approaches and future perspectives

The curry powder spices turmeric (Curcuma longa L.), which contains curcumin (diferuloylmethane), an orange-yellow chemical. Polyphenols are the most commonly used sources of curcumin. It combats oxidative stress and inflammation in diseases, such as hyperlipidemia, metabolic syndrome, arthritis, and depression. Most of these benefits are due to their anti-inflammatory and antioxidant properties. Curcumin consumption leads to decreased bioavailability, resulting in limited absorption, quick metabolism, and quick excretion, which hinders health improvement. Numerous factors can increase its bioavailability. Piperine enhances bioavailability when combined with curcumin in a complex. When combined with other enhancing agents, curcumin has a wide spectrum of health benefits. This review evaluates the therapeutic potential of curcumin with a specific emphasis on its approach based on molecular signaling pathways. This study investigated its influence on the progression of cancer, inflammation, and many health-related mechanisms, such as cell proliferation, apoptosis, and metastasis. Curcumin has a significant potential for the prevention and treatment of various diseases. Curcumin modulates several biochemical pathways and targets involved in cancer growth. Despite its limited tissue accumulation and bioavailability when administered orally, curcumin has proven useful. This review provides an in-depth analysis of curcumin's therapeutic applications, its molecular signaling pathway-based approach, and its potential for precision medicine in cancer and human health.

Effects of curcumin on non-alcoholic fatty liver disease: A scientific metrogy study

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases encountered in clinical practice. Curcumin can alleviate insulin resistance, inhibit oxidative stress response, reduce inflammation, reduce liver fat deposition, and effectively improve NAFLD through various modalities, inhibiting the progression into cirrhosis and fibrosis.

PURPOSE

To explore the current status, hot spots, and developing trends of curcumin in NAFLD treatment through quantitative scientific analysis to serve as a reference for subsequent studies.

STUDY DESIGN

A comprehensive analysis of the mechanism of action of curcumin in the treatment of NAFLD and methods to increase curcumin bioavailability using bibliometric analysis and literature review.

METHODS

This study used VOSviewer software to analyze the literature related to curcumin treatment of NAFLD in the Web of Science (WOS) core set database. A comprehensive and in-depth review was conducted based on the results of scientific econometric research and literature review.

RESULTS

The review observed that curcumin can activate various signaling pathways such as AMPK and NF-κB to inhibit oxidative stress and apoptosis, thereby reflecting its pharmacological effects: lowering lipid, anti-inflammatory, reducing insulin resistance, and anti-fibrosis. These mechanisms improve or even reverse the complex pathological features of lipid metabolism disorders associated with NAFLD. Curcumin also can potentially serve as a primary regulatory target for treating hepatic steatosis using gut microbiota. However, these pharmacological effects of curcumin were limited owing to its low bioavailability.

CONCLUSION

This review discusses NAFLD treatment with curcumin, analyzes the reasons for its low bioavailability, and introduces models for studying and methods for improving curcumin bioavailability. As research on NAFLD grows, future research should capture the trend of basic research, pay attention to clinical research, and continuously explore the therapeutic potential of curcumin.

Gut microbes in metabolic disturbances. Promising role for therapeutic manipulations?

The prevalence of overweight, obesity, type 2 diabetes, metabolic syndrome and steatotic liver disease is rapidly increasing worldwide with a huge economic burden in terms of morbidity and mortality. Several genetic and environmental factors are involved in the onset and development of metabolic disorders and related complications. A critical role also exists for the gut microbiota, a complex polymicrobial ecology at the interface of the internal and external environment. The gut microbiota contributes to food digestion and transformation, caloric intake, and immune response of the host, keeping the homeostatic control in health. Mechanisms of disease include enhanced energy extraction from the non-digestible dietary carbohydrates, increased gut permeability and translocation of bacterial metabolites which activate a chronic low-grade systemic inflammation and insulin resistance, as precursors of tangible metabolic disorders involving glucose and lipid homeostasis. The ultimate causative role of gut microbiota in this respect remains to be elucidated, as well as the therapeutic value of manipulating the gut microbiota by diet, pre- and pro- synbiotics, or fecal microbial transplantation.

Molecular Mechanisms of Curcumin in the Pathogenesis of Metabolic Dysfunction Associated Steatotic Liver Disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a multifactorial condition characterized by insulin resistance, oxidative stress, chronic low-grade inflammation, and sometimes fibrosis. To date, no effective pharmacological therapy has been approved for the treatment of metabolic-associated steatohepatitis (MASH), the progressive form of MASLD. Recently, numerous in vitro and in vivo studies have described the efficacy of nutraceutical compounds in the diet has been tested. Among them, curcumin is the most widely used polyphenol in the diet showing potent anti-inflammatory and antifibrotic activities. This review aims to summarize the most important basic studies (in vitro and animal models studies), describing the molecular mechanisms by which curcumin acts in the context of MASLD, providing the rationale for its effective translational use in humans.

The Dose-Dependent Effect of Curcumin Supplementation on Inflammatory Response and Gut Microbiota Profile in High-Fat Fed C57BL/6 Mice

SCOPE

The prevalence of obesity has increased, with excessive consumption of high-fat foods being one of the primary causes. Curcumin, a polyphenol extracted from Curcuma longa L., exhibits anti-inflammatory activity.  The study aims to investigate the effects of curcumin supplementation in different doses on the biochemical profile, inflammatory response, and gut microbiota profile in mice that are fed with high-fat diet (HFD).

METHODS AND RESULTS

C57BL/6 male mice are fed a standard diet, or a HFD with or without different doses of curcumin (50, 250, and 500 mg kg-1 of body weight). Throughout the experimental period, food intake and body weight are assessed weekly. At euthanasia, blood, stool, and tissue samples are collected for biochemical, histological, and molecular analyses. Curcumin increases the IL-10 protein expression in the white adipose tissue. In the liver, there is a reduction in tumor necrosis factor alpha (TNF-α) and an increase in IL-10 gene expression. Also, curcumin promotes the growth of butyrogenic bacteria, such as Clostridium clusters IV and XIVa.

CONCLUSIONS

The findings suggest that curcumin has the potential to improve the inflammatory response and modulate healthy gut microbiota. Further studies are needed to clarify the role of curcumin as a preventive and effective strategy for obesity.

Qushi Huayu decoction ameliorates non-alcoholic fatty liver disease in rats by modulating gut microbiota and serum lipids

Introduction

Non-alcoholic fatty liver disease (NAFLD) is a multifactorial disease. As a clinical empirical prescription of traditional Chinese medicine, Qushi Huayu decoction (QHD) has attracted considerable attention for its advantages in multi-target treatment of NAFLD. However, the intervention mechanism of QHD on abnormal lipid levels and gut microbiota in NAFLD has not been reported.

Methods

Therefore, we verified the therapeutic effect of QHD on high-fat diet (HFD)-induced NAFLD in rats by physiological parameters and histopathological examination. In addition, studies on gut microbiota and serum lipidomics based on 16S rRNA sequencing and ultra-high performance liquid chromatography-mass spectrometry (UPLC-MS) were conducted to elucidate the therapeutic mechanism of NAFLD in QHD.

Results

The changes in gut microbiota in NAFLD rats are mainly reflected in their diversity and composition, while QHD treated rats restored these changes. The genera Blautia, Lactobacillus, Allobaculum, Lachnoclostridium and Bacteroides were predominant in the NAFLD group, whereas, Turicibacter, Blautia, Sporosarcina, Romboutsia, Clostridium_sensu_stricto_1, Allobaculum, and Psychrobacter were predominant in the NAFLD+QHD group. Lipid subclasses, including diacylglycerol (DG), triglycerides (TG), phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidic acid (PA), phosphatidylserine (PS), lysophosphatidylinositol (LPI), and phosphatidylglycerol (PG), were significantly different between the NAFLD and the control groups, while QHD treatment significantly altered the levels of DG, TG, PA, lysophosphatidylcholine (LPC), lysophosphatidylethanolamine (LPE), and platelet activating factor (PAF). Finally, Spearman's correlation analysis showed that NAFLD related differential lipid molecules were mainly associated with the genera of Bacteroides, Blautia, Lachnoclostridium, Clostridium_sensu_stricto_1, and Turicibacter, which were also significantly correlated with the biological parameters of NAFLD.

Discussion

Taken together, QHD may exert beneficial effects by regulating the gut microbiota and thus intervening in serum lipids.

Interactions between gut microbiota and polyphenols: A mechanistic and metabolomic review

BACKGROUND

Polyphenols are a class of naturally sourced compounds with widespread distribution and an extensive array of bioactivities. However, due to their complex constituents and weak absorption, a convincing explanation for their remarkable bioactivity remains elusive for a long time. In recent years, interaction with gut microbiota is hypothesized to be a reasonable explanation of the potential mechanisms for natural compounds especially polyphenols.

OBJECTIVES

This review aims to present a persuasive explanation for the contradiction between the limited bioavailability and the remarkable bioactivities of polyphenols by examining their interactions with gut microbiota.

METHODS

We assessed literatures published before April 10, 2023, from several databases, including Scopus, PubMed, Google Scholar, and Web of Science. The keywords used include "polyphenols", "gut microbiota", "short-chain fatty acids", "bile acids", "trimethylamine N-oxide", "lipopolysaccharides" "tryptophan", "dopamine", "intestinal barrier", "central nervous system", "lung", "anthocyanin", "proanthocyanidin", "baicalein", "caffeic acid", "curcumin", "epigallocatechin-3-gallate", "ferulic acid", "genistein", "kaempferol", "luteolin", "myricetin", "naringenin", "procyanidins", "protocatechuic acid", "pterostilbene", "quercetin", "resveratrol", etc. RESULTS: The review first demonstrates that polyphenols significantly alter gut microbiota diversity (α- and β-diversity) and the abundance of specific microorganisms. Polyphenols either promote or inhibit microorganisms, with various factors influencing their effects, such as dosage, treatment duration, and chemical structure of polyphenols. Furthermore, the review reveals that polyphenols regulate several gut microbiota metabolites, including short-chain fatty acids, dopamine, trimethylamine N-oxide, bile acids, and lipopolysaccharides. Polyphenols affect these metabolites by altering gut microbiota composition, modifying microbial enzyme activity, and other potential mechanisms. The changed microbial metabolites induced by polyphenols subsequently trigger host responses in various ways, such as acting as intestinal acid-base homeostasis regulators and activating on specific target receptors. Additionally, polyphenols are transformed into microbial derivatives by gut microbiota and these polyphenols' microbial derivatives have many potential advantages (e.g., increased bioactivity, improved absorption). Lastly, the review shows polyphenols maintain intestinal barrier, central nervous system, and lung function homeostasis by regulating gut microbiota.

CONCLUSION

The interaction between polyphenols and gut microbiota provides a credible explanation for the exceptional bioactivities of polyphenols. This review aids our understanding of the underlying mechanisms behind the bioactivity of polyphenols.

Dietary factors in nonalcoholic fatty liver disease: impacts on human and animal health - a review

Non-alcoholic fatty liver disease (NAFLD) is defined as a clinical syndrome characterized by excessive fat accumulation in liver, predominantly influenced by dietary choices. This study provides an extensive quantitative literature analysis on dietary influences on NAFLD. Bibliometric data were collected through the search string TOPIC = (“NAFLD*” OR “nonalcoholic fatty liver*” OR “non-alcoholic fatty liver*”) AND TOPIC = (“diet*” OR “nutrition*” OR “food*” OR “feed*”), which yielded 12,445 publications indexed within the Web of Science Core Collection. Utilizing VOSviewer software, term maps were generated to visually illustrate recurring phrases alongside citation data. The literature, which has seen exponential growth since the 2010s, predominantly consists of original articles, with a ratio of 4.7:1 compared to reviews. Notably, the significant contributors to this field were China and the United States. The majority of publications were found journals specialized in Gastroenterology & Hepatology, Nutrition & Dietetics, Biochemistry & Molecular Biology, Endocrinology & Metabolism, and Pharmacology & Pharmacy. Key dietary compounds/compounds classes such as resveratrol, polyphenols, curcumin, berberine, quercetin, flavonoids, omega-3 fatty acids, docosahexaenoic acid (DHA), genistein, and palmitic acid were frequently mentioned and cited. Many of them were demonstrated to have some potential benefits on NAFLD, both in human and animal studies.

The bioavailability, metabolism and microbial modulation of curcumin-loaded nanodelivery systems

Curcumin (Cur), the major bioactive component of turmeric (Curcuma longa) possesses many health benefits. However, low solubility, stability and bioavailability restricts its applications in food. Recently, nanocarriers such as complex coacervates, nanocapsules, liposomes, nanoparticles, nanomicelles, have been used as novel strategies to solve these problems. In this review, we have focused on the delivery systems responsive to the environmental stimuli such as pH-responsive, enzyme-responsive, targeted-to-specific cells or tissues, mucus-penetrating and mucoadhesive carriers. Besides, the metabolites and their biodistribution of Cur and Cur delivery systems are discussed. Most importantly, the interaction between Cur and their carriers with gut microbiota and their effects of modulating the gut health synergistically were discussed comprehensively. In the end, the biocompatibility of Cur delivery systems and the feasibility of their application in food industry is discussed. This review provided a comprehensive review of Cur nanodelivery systems, the health impacts of Cur nanocarriers and an insight into the application of Cur nanocarriers in food industry.

The role of curcumin in the liver-gut system diseases: from mechanisms to clinical therapeutic perspective

Natural products have provided abundant sources of lead compounds for new drug discovery and development over the past centuries. Curcumin is a lipophilic polyphenol isolated from turmeric, a plant used in traditional Asian medicine for centuries. Despite the low oral bioavailability, curcumin exhibits profound medicinal value in various diseases, especially liver and gut diseases, bringing an interest in the paradox of its low bioavailability but high bioactivity. Several latest studies suggest that curcumin's health benefits may rely on its positive gastrointestinal effects rather than its poor bioavailability solely. Microbial antigens, metabolites, and bile acids regulate metabolism and immune responses in the intestine and liver, suggesting the possibility that the liver-gut axis bidirectional crosstalk controls gastrointestinal health and diseases. Accordingly, these pieces of evidence have evoked great interest in the curcumin-mediated crosstalk among liver-gut system diseases. The present study discussed the beneficial effects of curcumin against common liver and gut diseases and explored the underlying molecular targets, as well as collected evidence from human clinical studies. Moreover, this study summarized the roles of curcumin in complex metabolic interactions in liver and intestine diseases supporting the application of curcumin in the liver-gut system as a potential therapeutic option, which opens an avenue for clinical use in the future.

Effects of Curcumin on Growth Performance, Ruminal Fermentation, Rumen Microbial Protein Synthesis, and Serum Antioxidant Capacity in Housed Growing Lambs

This experiment was conducted to investigate growth performance, ruminal fermentation, rumen microbial protein synthesis, and serum antioxidant capacity with different doses of curcumin (CUR) included in the diet of housed growing lambs. Forty-eight four-month-old Dorper × Thin-tailed Han F₁ crossbred male lambs (body weight = 20.89 ± 1.15 kg, age = 120 ± 10 days; mean ± SD) were randomly divided into four groups for a single-factor, completely randomized experiment. Treatments comprised the following: the basal diet supplemented with 0 (Control), 300 mg/kg (300 CUR), 600 mg/kg (600 CUR), or 900 mg/kg (900 CUR) CUR, respectively. The results showed that dietary CUR increased average daily gain (ADG), and the 300 CUR group evidenced the highest value. There were no significant effects on dry matter intake (DMI) and DMI/ADG. Lambs in the 300 CUR group showed higher totals of volatile fatty acids (VFA) and acetate than other groups, while decreased valerate was observed with supplementary CUR. The ruminal pH and ammonia N (NH₃-N) concentration decreased with increasing CUR, with the greatest effect in the 300 CUR group. The quadratic effects were found in pectinase, carboxymethyl cellulose, and protease, with the greatest value in the 300 CUR group. The microbial populations of total bacteria and Ruminococcus albus also responded quadratically, and the methanogens, protozoan, and Fibrobacter succinogenes populations decreased linearly with increasing CUR. Lambs receiving additional CUR showed increased Prevotella ruminicola population. Microbial protein (MCP) synthesis was promoted by supplementary CUR. As supplementation with CUR increased, the serum activity of total antioxidant capacity (T-AOC), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) was enhanced, with the greatest value in the 300 CUR group. In conclusion, dietary CUR improved ruminal fermentation, promoted rumen microbial protein (MCP) synthesis, and enhanced serum antioxidant activity, as well as promoting growth performance in housed growing lambs.

Effects of Different Vegetable Oils on the Nonalcoholic Fatty Liver Disease in C57/BL Mice

Background

Nonalcoholic fatty liver disease (NAFLD) is the most common hepatic disorder, affecting 22-28% of the adult population and more than 50% of obese people all over the world. Modulation of the fatty acids in diet as a means of prevention against nonalcoholic fatty liver disease in animal models (NAFLD) remains unclear. The treatment of NAFLD has not been described in specific guidelines so far. Thus, the justification for the study is to check modifications in macronutrients composition, fatty acids, in particular, play a significant role in the treatment of NAFLD regardless of weight loss.

Aim

To investigate different vegetable oils in prevention and progression of NAFLD in animal models.

Methods

For the experiment were used fifty C57BL/6J mice male fed with high fat and fructose diet (HFD) to induce the NAFLD status and they received different commercial vegetable oils for 16 weeks to prevent steatosis. Liver steatosis and oxidative stress parameters were analyzed using biochemical and histological methods. Fatty acids profile in the oils and in the liver samples was obtained.

Results

The high fat and fructose diet led to obesity and the vegetable oils offered were effective in maintaining body weight similar to the control group. At the end of the experiment (16 weeks), the HFHFr group had a greater body weight compared to control and treated groups (HFHFr: 44.20 ± 2.34 g/animal vs. control: 34.80 ± 3.45 g/animal; p < 0.001; HFHFr/OL: 35.40 ± 4.19 g/animal; HFHFr/C: 36.10 ± 3.92 g/animal; HFHFr/S: 36.25 ± 5.70 g/animal; p < 0.01). Furthermore, the HFD diet has caused an increase in total liver fat compared to control (p < 0.01). Among the treated groups, the animals receiving canola oil showed a reduction of hepatic and retroperitoneal fat (p < 0.05). These biochemical levels were positively correlated with the hepatic histology findings. Hepatic levels of omega-3 decreased in the olive oil and high fat diet groups compared to the control group, whereas these levels increased in the groups receiving canola and soybean oil compared to control and the high fat groups.

Conclusion

In conclusion, the commercial vegetable oils either contributed to the prevention or reduction of induced nonalcoholic fatty liver with high fat and fructose diet, especially canola oil.

Bioactive dietary components-Anti-obesity effects related to energy metabolism and inflammation

Obesity is the result of the long-term energy imbalance between the excess calories consumed and the few calories expended. Reducing the intake of energy dense foods (fats, sugars), and strategies such as fasting and caloric restriction can promote body weight loss. Not only energy in terms of calories, but also the specific composition of the diet can affect the way the food is absorbed and how its energy is stored, used or dissipated. Recent research has shown that bioactive components of food, such as polyphenols and vitamins, can influence obesity and its pathologic complications such as insulin resistance, inflammation and metabolic syndrome. Individual micronutrients can influence lipid turnover but for long-term effects on weight stability, dietary patterns containing several micronutrients may be required. At the molecular level, these molecules modulate signaling and the expression of genes that are involved in the regulation of energy intake, lipid metabolism, adipogenesis into white, beige and brown adipose tissue, thermogenesis, lipotoxicity, adipo/cytokine synthesis, and inflammation. Higher concentrations of these molecules can be reached in the intestine, where they can modulate the composition and action of the microbiome. In this review, the molecular mechanisms by which bioactive compounds and vitamins modulate energy metabolism, inflammation and obesity are discussed.

Spice-Derived Bioactive Compounds Confer Colorectal Cancer Prevention via Modulation of Gut Microbiota

Colorectal cancer (CRC) is the second most frequent cause of cancer-related mortality among all types of malignancies. Sedentary lifestyles, obesity, smoking, red and processed meat, low-fiber diets, inflammatory bowel disease, and gut dysbiosis are the most important risk factors associated with CRC pathogenesis. Alterations in gut microbiota are positively correlated with colorectal carcinogenesis, as these can dysregulate the immune response, alter the gut's metabolic profile, modify the molecular processes in colonocytes, and initiate mutagenesis. Changes in the daily diet, and the addition of plant-based nutraceuticals, have the ability to modulate the composition and functionality of the gut microbiota, maintaining gut homeostasis and regulating host immune and inflammatory responses. Spices are one of the fundamental components of the human diet that are used for their bioactive properties (i.e., antimicrobial, antioxidant, and anti-inflammatory effects) and these exert beneficial effects on health, improving digestion and showing anti-inflammatory, immunomodulatory, and glucose- and cholesterol-lowering activities, as well as possessing properties that affect cognition and mood. The anti-inflammatory and immunomodulatory properties of spices could be useful in the prevention of various types of cancers that affect the digestive system. This review is designed to summarize the reciprocal interactions between dietary spices and the gut microbiota, and highlight the impact of dietary spices and their bioactive compounds on colorectal carcinogenesis by targeting the gut microbiota.

Curcumin improves insulin sensitivity in high-fat diet-fed mice through gut microbiota

Background

Insulin resistance precedes metabolic syndrome which increases the risk of type 2 diabetes and cardiovascular disease. However, there is a lack of safe and long-lasting methods for the prevention and treatment of insulin resistance. Gut microbiota dysbiosis can lead to insulin resistance and associated glucose and lipid metabolic dysfunction. Thus, the role of gut microbiota in metabolic diseases has garnered growing interest. Curcumin, the active ingredient of tropical plant Curcuma longa, has excellent prospects for the prevention and treatment of metabolic diseases. However, due to the extremely low bioavailability of curcumin, the mechanisms by which curcumin increases insulin sensitivity remains to be elucidated. This study aimed to elucidate the role of gut microbiota in mediating the effects of curcumin on improving insulin sensitivity in high-fat diet (HFD)-fed mice.

Methods

Glucose, insulin, and pyruvate tolerance were tested and hepatic triglycerides (TGs) content was measured in HFD-fed mice treated with curcumin (100 mg kg−1 d−1, p.o.) or vehicle for 4 weeks and aforementioned mice after gut microbiota depletion via antibiotic treatment for 4 weeks. Fecal microbiota transplantation (FMT) was conducted in endogenous gut microbiota-depleted HFD-fed mice. Glucose and lipid metabolic phenotypes were also measured in recipient mice colonized microbiota from vehicle- or curcumin-treated HFD-fed mice. The mechanisms underlying the effects of curcumin on increasing insulin sensitivity were testified by Western blotting, real-time quantitative polymerase chain reaction and enzyme-linked immunosorbent assay (ELISA).

Results

Curcumin ameliorated HFD-induced glucose intolerance, insulin resistance, pyruvate intolerance, and hepatic TGs accumulation, while these effects were mediated by gut microbiota. Curcumin induced insulin-stimulated Akt phosphorylation levels in insulin-regulated peripheral tissues. The inhibitory effects of curcumin on the expressions of genes involved in hepatic gluconeogenesis and de novo lipogenesis were dependent on gut microbiota. Meanwhile, curcumin upregulated the expression of fibroblast growth factor 15 (FGF15) through gut microbiota.

Conclusions

The effects of curcumin on promoting insulin sensitivity were dependent on gut microbiota in HFD-fed mice. Moreover, curcumin at least partly exerted its effects on increasing insulin sensitivity via FGF15 upregulation. This study provided new ideas on nutritional manipulations of gut microbiota for the treatment of metabolic diseases.

Preventive Effects of Different Black and Dark Teas on Obesity and Non-Alcoholic Fatty Liver Disease and Modulate Gut Microbiota in High-Fat Diet Fed Mice

Non-alcoholic fatty liver disease (NAFLD) has emerged as a leading public health challenge and is closely associated with metabolic syndromes, such as obesity. Intestinal microbiota dysbiosis could play a vital role in the pathogenesis and progression of NAFLD. Tea is the second most popular health drink in the world behind water, and exhibits many health-promoting effects. In this study, the protective effects of different black and dark teas on NAFLD induced by long-term high-fat diet (HFD) exposure and their regulation of gut microbiota were evaluated and explored. The results indicated that supplementation with different black and dark tea extracts could significantly suppress the energy intake, alleviate abnormal accumulation of visceral fat, and prevent obesity, hepatic abnormal lipid deposition and liver steatosis in HFD-fed mice at varying degrees. In addition, Dianhong tea and Liupao tea interventions could significantly decrease the ratio of Firmicutes to Bacteroidetes, and selenium-enriched black tea and selenium-enriched dark rea supplementation could remarkably reduce the relative abundance of Actinobacteria compared to the model group. Moreover, these teas could partly shift the relative abundances of Allobaculum, Roseburia and Dubosiella. Taken together, black teas and dark teas could prevent HFD-induced features of obesity and NAFLD, which might partly be due to the modulation of gut microbiota.

Curcumin attenuates cadmium-induced atherosclerosis by regulating trimethylamine-N-oxide synthesis and macrophage polarization through remodeling the gut microbiota

BACKGROUND

Studies have shown that cadmium (Cd) exposure primarily occurs through diet, and Cd ingestion is a risk factor for atherosclerosis (AS). However, the underlying mechanism remains unclear. As a target organ, the gastrointestinal tract may play a key role in Cd-induced AS. Additionally, as curcumin is insoluble in water but stable in the stomach of acidic pH, it may play regulative roles in the gut.

OBJECTIVES

We assess the effect of Cd exposure on gut flora, trimethylamine-N-oxide (TMAO) metabolism and macrophage polarization, further investigate whether curcumin protects against Cd-induced AS by remodeling gut microbiota.

METHODS AND RESULTS

The results of 16 S rRNA sequencing show that Cd exposure causes diversity reduction and compositional alteration of the microbial community, resulting in the increasing TMAO synthesis, the imbalance of lipid metabolism, and the M1-type macrophage polarization in the mouse model (ApoE^-/-) of AS. As a result, the plaque area is increased with Cd exposure, shown by oil red O staining. TMAO synthesis is positively correlated with the concentration of blood Cd, and the dynamics of specific bacteria in this process were revealed at the phylum to genus levels. Moreover, the effects of intestinal flora and TMAO on Cd-induced AS are further confirmed via microbial transplantation from a mouse model not exposed to Cd, as the transplantation decreases plaque area. Finally, the gavage with curcumin reverses the Cd-induced pathological progression via gut flora restoration.

CONCLUSIONS

We first demonstrate that Cd exposure worsens the progression of AS via intestinal flora imbalance and increased TMAO synthesis. Curcumin was verified as a potential novel intervention for preventing Cd-induced AS via remodeling gut microbiota. This study elucidates a new approach for treating AS in regions with significant Cd exposure.

Phytic Acid Improves Hepatic Steatosis, Inflammation, and Oxidative Stress in High-Fat Diet (HFD)-Fed Mice by Modulating the Gut-Liver Axis

Nonalcoholic fatty liver disease (NAFLD) induced by obesity is a grave threat to human health. Phytic acid (PA) is a natural compound found in high-fiber diets, such as soybeans. This study investigated the effects and mechanisms of PA on obesity, hepatic lipid metabolism, and gut-liver axis homeostasis in high-fat diet (HFD)-fed mice. PA was observed to significantly inhibit obesity and alleviate liver steatosis in mice. PA improved HFD-induced liver inflammation, oxidative stress and fibrosis. Moreover, PA improved HFD-induced colonic inflammation, gut barrier damage and systemic inflammation in mice. Furthermore, PA effectively ameliorated the decreased diversity and gut microbiota composition in HFD-fed mice. Additionally, PA decreased the abundance of harmful bacteria Proteobacteria and Desulfovibrionaceae and increased the abundance of probiotic bacteria Muribaculaceae and Lachnospiraceae. Thus, PA is effective in restoring the homeostasis of the gut-liver axis. It further provides a theoretical basis for the prevention and treatment of NAFLD in patients with obesity by the rational intake of foods containing PA.

Shifts in the intestinal microflora of meat rabbits in response to glucocorticoids

BACKGROUND

As major stress hormones, glucocorticoids can directly or indirectly affect the intestinal microflora, although few studies have focused on changes in the composition of the intestinal microflora. In this study, rabbits were randomly divided into two groups: gavage administration with saline, and the same doses of dexamethasone (1 mg kg^-1 ). After 7 days, the microbial diversity of the jejunum contents was analysed.

RESULTS

The gut microflora richness and diversity had no significant difference between the two groups. The proportions of Firmicutes and Bacteroidetes were the most abundant in the jejunum of meat rabbits. Dexamethasone injection led to a change in the structure of the gut microflora composition, and we found that there were six biomarkers with linear discriminant analysis score >4 (Firmicutes, Caproiciproducens, Clostridiales, Clostridia, Psychrobacter, and Psychrobacter faecalis), moreover, the results of this study provide new insight into alleviating the effects of stress on meat rabbits.

CONCLUSION

It was concluded that glucocorticoids caused changes in the composition of intestinal microflora. © 2022 Society of Chemical Industry.

The Impact of Plant Phytochemicals on the Gut Microbiota of Humans for a Balanced Life

The gastrointestinal tract of humans is a complex microbial ecosystem known as gut microbiota. The microbiota is involved in several critical physiological processes such as digestion, absorption, and related physiological functions and plays a crucial role in determining the host’s health. The habitual consumption of specific dietary components can impact beyond their nutritional benefits, altering gut microbiota diversity and function and could manipulate health. Phytochemicals are non-nutrient biologically active plant components that can modify the composition of gut microflora through selective stimulation of proliferation or inhibition of certain microbial communities in the intestine. Plants secrete these components, and they accumulate in the cell wall and cell sap compartments (body) for their development and survival. These compounds have low bioavailability and long time-retention in the intestine due to their poor absorption, resulting in beneficial impacts on gut microbiota population. Feeding diets containing phytochemicals to humans and animals may offer a path to improve the gut microbiome resulting in improved performance and/or health and wellbeing. This review discusses the effects of phytochemicals on the modulation of the gut microbiota environment and the resultant benefits to humans; however, the effect of phytochemicals on the gut microbiota of animals is also covered, in brief.

Reconnoitering the Therapeutic Role of Curcumin in Disease Prevention and Treatment: Lessons Learnt and Future Directions

Turmeric is a plant with a very long history of medicinal use across different cultures. Curcumin is the active part of turmeric, which has exhibited various beneficial physiological and pharmacological effects. This review aims to critically appraise the corpus of literature associated with the above pharmacological properties of curcumin, with a specific focus on antioxidant, anti-inflammatory, anticancer and antimicrobial properties. We have also reviewed the different extraction strategies currently in practice, highlighting the strengths and drawbacks of each technique. Further, our review also summarizes the clinical trials that have been conducted with curcumin, which will allow the reader to get a quick insight into the disease/patient population of interest with the outcome that was investigated. Lastly, we have also highlighted the research areas that need to be further scrutinized to better grasp curcumin’s beneficial physiological and medicinal properties, which can then be translated to facilitate the design of better bioactive therapeutic leads.

The role of microbiota in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most frequent liver disease worldwide. Gut microbiota can play a role in the pathogenesis of NAFLD since dysbiosis is associated with reduced bacterial diversity, altered Firmicutes/Bacteroidetes ratio, a relative abundance of alcohol-producing bacteria, or other specific genera. Changes can promote disrupted intestinal barrier and hyperpermeability, filtration of bacterial products, activation of the immune system, and pro-inflammatory changes in the intestine, in the liver, and at a systemic level. Microbiota-derived molecules can contribute to the steatogenic effects. The link between gut dysbiosis and NAFLD, however, is confused by several factors which include age, BMI, comorbidities, dietary components, and lifestyle. The role of toxic chemicals in food and water requires further studies in both gut dysbiosis and NAFLD. We can anticipate that gut microbiota manipulation will represent a potential therapeutic tool to delay or reverse the progression of NAFLD, paving the way to primary prevention measures.

Protective Effects of Lacticaseibacillus rhamnosus Hao9 on Dextran Sulphate Sodium-Induced Ulcerative Colitis in Mice

AIMS

Some probiotics used as food additives or food supplements had anti-inflammatory effect. We tested the potential protective effects of probiotic Lacticaseibacillus rhamnosus Hao9 (Hao9) in mice with dextran sulphate sodium (DSS)-induced ulcerative colitis (UC) and determined whether these effects were related to the modulation of gut microbiota and amelioration of inflammation.

METHODS AND RESULTS

UC mouse model was established by feeding mice with 2.5% (w/v) DSS in drinking water for 7 days. We analysed the disease activity index (DAI), colon length, and histological changes in the colon. In addition, we investigated the effects of Hao9 (1 × 10⁹ CFU/day) and curcumin (CUR) (200 mg/kg/day) on gut microbiota and serum inflammatory cytokines. In this study, CUR was used as a positive control. The results showed that both Hao9 and CUR effectively reduced body mass loss and DAI, restored colon length, alleviated colonic pathological variations, and reduced histological scores compared with the UC group. Hao9 reduced the serum concentrations of proinflammatory cytokines (TNF-α, IL-6, and IL-1β) and increased the concentration of the anti-inflammatory cytokine IL-10. In addition, Hao9 promoted the growth of Faecalibaculum and Romboutsia in the gut and helped to maintain intestinal homeostasis.

CONCLUSIONS

Hao9 had a protective effect against DSS-induced colitis, and the mechanisms underlying Hao9 may involve controlling inflammation and maintaining host microecological balance. This study provided experimental evidence for the application of Hao9 in the treatment of ulcerative colitis and suggested that Hao9 may be a promising candidate as a dietary supplement against colitis.

SIGNIFICANCE AND IMPACT OF THE STUDY

The comparison of probiotics and prebiotics in terms of therapeutic efficacy in UC helps us to understand their different patterns of regulation of intestinal microbiota.

Effect of maternal curcumin supplementation on intestinal damage and the gut microbiota in male mice offspring with intra-uterine growth retardation

PURPOSE

The present study investigated whether maternal curcumin supplementation might protect against intra-uterine growth retardation (IUGR) induced intestinal damage and modulate gut microbiota in male mice offspring.

METHODS

In total, 36 C57BL/6 mice (24 females and 12 males, 6-8 weeks old) were randomly divided into three groups based on the diet before and throughout pregnancy and lactation: (1) normal protein (19%), (2) low protein (8%), and (3) low protein (8%) + 600 mg kg-1 curcumin. Offspring were administered a control diet until postnatal day 35.

RESULTS

Maternal curcumin supplementation could normalize the maternal protein deficiency-induced decrease in jejunal SOD activity (NP = 200.40 ± 10.58 U/mg protein; LP = 153.30 ± 5.51 U/mg protein; LPC = 185.40 ± 9.52 U/mg protein; P < 0.05) and T-AOC content (NP = 138.90 ± 17.51 U/mg protein; LP = 84.53 ± 5.42 U/mg protein; LPC = 99.73 ± 12.88 U/mg protein; P < 0.05) in the mice offspring. Maternal curcumin supplementation increased the maternal low protein diet-induced decline in the ratio of villus height-to-crypt depth (NP = 2.23 ± 0.19; LP = 1.90 ± 0.06; LPC = 2.56 ± 0.20; P < 0.05), the number of goblet cells (NP = 12.72 ± 1.16; LP = 7.04 ± 0.53; LPC = 13.10 ± 1.17; P < 0.05), and the ratio of PCNA-positive cells (NP = 13.59 ± 1.13%; LP = 2.42 ± 0.74%; LPC = 6.90 ± 0.96%; P < 0.05). It also reversed the maternal protein deficiency-induced increase of the body weight (NP = 13.00 ± 0.48 g; LP = 16.49 ± 0.75 g; LPC = 10.65 ± 1.12 g; P < 0.05), the serum glucose levels (NP = 5.32 ± 0.28 mmol/L; LP = 6.82 ± 0.33 mmol/L; LPC = 4.69 ± 0.35 mmol/L; P < 0.05), and the jejunal apoptotic index (NP = 6.50 ± 1.58%; LP = 10.65 ± 0.75%; LPC = 5.24 ± 0.71%; P < 0.05). Additionally, maternal curcumin supplementation enhanced the gene expression level of Nrf2 (NP = 1.00 ± 0.12; LP = 0.73 ± 0.10; LPC = 1.34 ± 0.12; P < 0.05), Sod2 (NP = 1.00 ± 0.04; LP = 0.85 ± 0.04; LPC = 1.04 ± 0.04; P < 0.05) and Ocln (NP = 1.00 ± 0.09; LP = 0.94 ± 0.10; LPC = 1.47 ± 0.09; P < 0.05) in the jejunum. Furthermore, maternal curcumin supplementation normalized the relative abundance of Lactobacillus (NP = 31.56 ± 6.19%; LP = 7.60 ± 2.33%; LPC = 17.79 ± 2.41%; P < 0.05) and Desulfovibrio (NP = 3.63 ± 0.93%; LP = 20.73 ± 3.96%; LPC = 13.96 ± 4.23%; P < 0.05), and the ratio of Firmicutes/Bacteroidota (NP = 2.84 ± 0.64; LP = 1.21 ± 0.30; LPC = 1.79 ± 0.15; P < 0.05). Moreover, Lactobacillus was positively correlated with the SOD activity, and it was negatively correlated with Il - 1β expression (P < 0.05). Desulfovibrio was negatively correlated with the SOD activity and the jejunal expression of Sod1, Bcl - 2, Card11, and Zo - 1 (P < 0.05).

CONCLUSIONS

Maternal curcumin supplementation could improve intestinal integrity, oxidative status, and gut microbiota in male mice offspring with IUGR.

Curcumin Supplementation Ameliorates Bile Cholesterol Supersaturation in Hamsters by Modulating Gut Microbiota and Cholesterol Absorption

Curcumin is a polyphenol that has been shown to have prebiotic and cholesterol-lowering properties. This study aimed to investigate the impact of curcumin on bile cholesterol supersaturation and the potential mechanistic role of intestinal microbiota and cholesterol absorption. Male hamsters (n = 8) were fed a high-fat diet (HFD) supplemented with or without curcumin for 12 weeks. Results showed that curcumin significantly decreased cholesterol levels in the serum (from 5.10 to 4.10 mmol/L) and liver (from 64.60 to 47.72 nmol/mg protein) in HFD-fed hamsters and reduced the bile cholesterol saturation index (CSI) from 1.64 to 1.08 due to the beneficial modifications in the concentration of total bile acids (BAs), phospholipids and cholesterol (p < 0.05). Gut microbiota analysis via 16S rRNA sequencing revealed that curcumin modulated gut microbiota, predominantly increasing microbiota associated with BA metabolism and short-chain fatty acid production, which subsequently up-regulated the expression of hepatic cholesterol 7-alpha hydroxylase and increased the synthesis of bile acids (p < 0.05). Furthermore, curcumin significantly down-regulated the expression of intestinal Niemann−Pick C1-like protein 1(NPC1L1) in hamsters and reduced cholesterol absorption in Caco-2 cells (p < 0.05). Our results demonstrate that dietary curcumin has the potential to prevent bile cholesterol supersaturation through modulating the gut microbiota and inhibiting intestinal cholesterol absorption.

Pterostilbene and Its Derivative 3'-Hydroxypterostilbene Ameliorated Nonalcoholic Fatty Liver Disease Through Synergistic Modulation of the Gut Microbiota and SIRT1/AMPK Signaling Pathway

Nonalcoholic fatty liver disease (NAFLD) is a recent chronic liver disease common in many developed countries and is closely associated with metabolic syndrome, such as obesity and insulin resistance. The present study was performed to investigate the effects of pterostilbene (Pt) and its derivative 3'-hydroxypterostilbene (OHPt) on free fatty acids (FFA)-induced lipid accumulation in HepG2 cells and high-fat diet (HFD)-induced NAFLD in C57BL/6J mice. The results showed that Pt and OHPt significantly ameliorated FFA-induced steatosis in HepG2 cells and enhanced lipolysis through the upregulation of SIRT1/AMPK and insulin signaling pathways. In the in vivo study, Pt and OHPt treatment resulted in reduced hepatic lipid droplets accumulation. The data showed that Pt and OHPt upregulated the SIRT1/AMPK pathway and subsequently downregulated the protein expression of SREBP-1 to activate fatty acid (FA) β-oxidation to inhibit FA synthesis. Pt and OHPt administration activated the insulin signaling pathway and further ameliorated the insulin resistance and liver function in the HFD-fed mice. Furthermore, Pt and OHPt markedly increased the numbers of Oscillospira and decreased the numbers of Allobaculum, Phascolarctobacterium, and Staphylococcus compared with those in the HFD group. These robust results indicate that Pt and OHPt are able to possess potential health benefits in improving insulin resistance and hepatic steatosis by promoting healthy populations or abundances of considered vital microbiota. Besides, OHPt is more effective than Pt, which might have promising chemotherapeutic effects for future clinical application.

The hepatoprotective effects of plant-based foods based on the "gut-liver axis": a prospective review

The importance of the "gut-liver axis" in the pathogenesis of liver diseases has been revealed recently; which promotes the process of developing preventive and therapeutic strategies. However, considering that there are still many challenges in the medical treatment of liver diseases, potential preventive dietary intervention may be a good alternative choice. Plant-based foods have received much attention due to their reported health-promoting effects in targeting multiple pathways involved in the pathogenesis of liver diseases as well as the relative safety for general use. Based on the PubMed and Web of Science databases, this review emphatically summarizes the plant-based foods and their chemical constituents with reported effects to impact the LPS/TLR4 signaling pathway of gut-liver axis of various liver diseases, reflecting their health benefits in preventing/alleviating liver diseases. Moreover, some plant-based foods with potential gut-liver effects are specifically analyzed from the reported studies and conclusions. This review intends to provide readers an overview of the current progress in the field of this research topic. We expect to see more hepatoprotective measures for alleviating the current prevalence of liver diseases.

Curcumin Alleviates DSS-Induced Anxiety-Like Behaviors via the Microbial-Brain-Gut Axis

The anxiety and depression caused by inflammatory bowel diseases (IBD) are known to greatly affect the mental health of patients. The mechanism of psychiatric disorders caused by IBD is not fully understood. Previous research has suggested that the gut microbiome plays a key role in IBD. Curcumin is a yellow polyphenol extracted from the rhizome of the ginger plant, which has been shown to have effects against both depression and anxiety. Research has indicated that curcumin affects the gut microbiome and exerts antianxiety and neuroprotective effects through the microbiota-gut-brain axis (MGB). However, whether curcumin can alleviate the psychiatric disorders caused by IBD and how curcumin affects the MGB axis through the gut microbiota have not been fully understood. Therefore, this study was aimed at determining the metabolic parameters and microbiological environment in the peripheral and central nervous system to determine the effects of curcumin against anxiety induced by dextran sulfate sodium salt (DSS) in mice. To elaborate on the link between the gut microbiota and how curcumin alleviates anxiety-like behaviors, we performed a fecal microbiota transplantation (FMT) experiment. The results suggested that curcumin can effectively relieve anxiety-like behaviors caused by DSS in mice. Further, curcumin treatment can alleviate disturbances in the gut microbiota and systemic disorders of lipid metabolism caused by DSS. Finally, through FMT, we verified that curcumin increased phosphatidylcholine in the prefrontal cortex of the mice and alleviated DSS-induced anxiety-like behaviors by modulating specific gut microbiota. We also revealed that Muribaculaceae may be a key part of the gut microbiota for curcumin to alleviate DSS-induced anxiety-like behaviors through the MGB axis.

Curcumin Mitigates TNFα-Induced Caco-2 Cell Monolayer Permeabilization Through modulation of NF-κB, ERK1/2 and JNK Pathways

SCOPE

This work studied the capacity of curcumin to inhibit TNFα-induced inflammation, oxidative stress, and loss of intestinal barrier integrity, characterizing the underlying mechanisms.

METHODS AND RESULTS

Caco-2 cell monolayers were incubated with TNFα (10 ng/ml), in the absence or presence of curcumin. TNFα caused an increase in interleukin (IL)-6 and IL-8 release which was inhibited by curcumin in a dose-dependent manner (IC₅₀ = 3.4 μM for IL-6). Moreover, TNFα led to: i) increased ICAM-1 and NLRP3 expression; ii) increased cell monolayer permeability and decreased levels of tight junction proteins; iii) increased cellular and mitochondrial oxidant production; iv) decreased mitochondrial membrane potential and complex I-III activity; v) activation of redox-sensitive pathways, i.e., NF-κB, ERK1/2 and JNK; and vi) increased MLCK expression and phosphorylation levels of MLC. Curcumin (2-8 μM) inhibited all these TNFα-triggered undesirable outcomes, mostly showing dose-dependent effects.

CONCLUSION

The inhibition of NF-κB, ERK1/2 and JNK activation could be in part involved in the capacity of curcumin to mitigate intestinal inflammation, oxidant production, activation of redox-sensitive pathways, and prevention of monolayer permeabilization. These results support an action of dietary curcumin in sustaining gastrointestinal tract physiology. This article is protected by copyright. All rights reserved.

Curcumin Supplementation (Meriva®) Modulates Inflammation, Lipid Peroxidation and Gut Microbiota Composition in Chronic Kidney Disease

Chronic kidney disease (CKD) subjects suffer from high risk of cardiovascular mortality, and any intervention preventing the progression of CKD may have an enormous impact on public health. In the last decade, there has been growing awareness that the gut microbiota (GM) can play a pivotal role in controlling the pathogenesis of systemic inflammatory state and CKD progression. To ameliorate the quality of life in CKD subjects, the use of dietary supplements has increased over time. Among those, curcumin has demonstrated significant in vitro anti-inflammatory properties. In this pilot study, 24 CKD patients and 20 healthy volunteers were recruited. CKD patients followed nutritional counselling and were supplemented with curcumin (Meriva^®) for six months. Different parameters were evaluated at baseline and after 3-6 months: uremic toxins, metagenomic of GM, and nutritional, inflammatory, and oxidative status. Curcumin significantly reduced plasma pro-inflammatory mediators (CCL-2, IFN-γ, and IL-4) and lipid peroxidation. Regarding GM, after 6 months of curcumin supplementation, Escherichia-Shigella was significantly lower, while Lachnoclostridium was significant higher. Notably, at family level, Lactobacillaceae spp. were found significantly higher in the last 3 months of supplementation. No adverse events were observed in the supplemented group, confirming the good safety profile of curcumin phytosome after long-term administration.

Calebin-A prevents HFD-induced obesity in mice by promoting thermogenesis and modulating gut microbiota

Background and aim

Obesity is one of the complications of sedentary lifestyle and high-calorie food intake which become a global problem. Thermogenesis is a novel way to promote anti-obesity by consuming energy as heat rather than storing it as triacylglycerols. Over the last decade, growing evidence has identified the gut microbiota as a potential factor in the pathophysiology of obesity. Calebin A is a non-curcuminoid novel compound derived from the rhizome of medicinal turmeric with putative anti-obesity effects. However, its ability on promoting thermogenesis and modulating gut microbiota remain unclear.

Experimental procedure

C57BL/6J mice were fed either normal diet or high-fat diet (HFD) supplement with calebin A (0.1 and 0.5%) diet for 12 weeks. The composition of the gut microbiota was assessed by analyzing 16S rRNA gene sequences.

Results and conclusion

Mice treated with calebin A shows a remarkable alteration in microbiota composition compared with that of normal diet-fed or HFD-fed mice and is characterized by an enrichment of Akkermansia, Butyricicoccus, Ruminiclostridium_9, and unidentified_Ruminococcaceae. We also explored that calebin A reduce the weight and blood sugar of mice that are induced by HFD, and show a dose-dependent reaction. Moreover, calebin A decreases the weight of white, beige, and brown adipose tissue, and also restores liver weight. In cold exposure experiments, calebin A can better maintain rectal temperature through thermogenesis. In summary, calebin A has a good thermogenesis function and is effective in anti-obesity. It can be used as a novel gut microbiota modulator to prevent HFD-induced obesity.

Intestinal Barrier and Permeability in Health, Obesity and NAFLD

The largest surface of the human body exposed to the external environment is the gut. At this level, the intestinal barrier includes luminal microbes, the mucin layer, gastrointestinal motility and secretion, enterocytes, immune cells, gut vascular barrier, and liver barrier. A healthy intestinal barrier is characterized by the selective permeability of nutrients, metabolites, water, and bacterial products, and processes are governed by cellular, neural, immune, and hormonal factors. Disrupted gut permeability (leaky gut syndrome) can represent a predisposing or aggravating condition in obesity and the metabolically associated liver steatosis (nonalcoholic fatty liver disease, NAFLD). In what follows, we describe the morphological-functional features of the intestinal barrier, the role of major modifiers of the intestinal barrier, and discuss the recent evidence pointing to the key role of intestinal permeability in obesity/NAFLD.