Modulating effects of capsaicin on glucose homeostasis and the underlying mechanism

Dietary capsaicin attenuates cardiac injury after myocardial infarction in type 2 diabetic mice by inhibiting ferroptosis through activation of TRPV1 and Nrf2/HMOX1 pathway

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a major 21st-century epidemic. T2DM elevates the risk of myocardial infarction and heart failure while also reducinges survival rates. Recently Ferroptosis has been found to be involved in the development of various cardiovascular diseases. TRPV1 is also a potential therapeutic target for cardioprotection. This study explores whether capsaicin, a transient receptor potential vanilloid receptor 1 (TRPV1) agonist, can prevent diabetic myocardial infarction-induced injury by inhibiting ferroptosis.

METHODS

T2DM model was induced by high-fat diet (HFD) feeding combined with streptozocin (STZ) injections, and the diabetic mice were treated with capsaicin(0.015 %) in their food. Myocardial infarction model was established as well. Mouse' general characteristics, cardiac function, and morphological histology were observed and analyzed. RNA-seq was used to investigate the possible mechanism of injury in AC16 cardiomyocytes cultured with high glucose and hypoxia. In addition, the potential mechanism of capsaicin against injury was further investigated in AC16 cardiomyocytes cultured with high glucose and hypoxia.

RESULTS

The RNA-seq analysis revealed that ferroptosis was associated with cell death induced by high-glucose in combination with hypoxia, and CAP treatment could effectively inhibit ferroptosis to enhance cell survival. In vivo studies demonstrated that CAP treatment significantly improved post-MI cardiac function, attenuated myocardial inflammation and fibrosis. Furthermore, it was observed that CAP reduced ferroptosis levels by activating TRPV1 in the heart, upregulating Nrf2 expression, promoting Nrf2 nuclear translocation and increasing the expression of the Nrf2 downstream molecule Heme oxygenase-1 (HMOX1).

CONCLUSIONS

Dietary capsaicin may inhibit cardiomyocyte ferroptosis through activation of myocardial TRPV1 and Nrf2/HMOX1 signaling pathway, which in turn exerts a protective effect on the myocardium after myocardial infarction in type 2 diabetic mice.

Ulcerative colitis: molecular insights and intervention therapy

Ulcerative colitis (UC) is a chronic inflammatory bowel disease characterized by abdominal pain, diarrhea, rectal bleeding, and weight loss. The pathogenesis and treatment of UC remain key areas of research interest. Various factors, including genetic predisposition, immune dysregulation, and alterations in the gut microbiota, are believed to contribute to the pathogenesis of UC. Current treatments for UC include 5-aminosalicylic acids, corticosteroids, immunosuppressants, and biologics. However, study reported that the one-year clinical remission rate is only around 40%. It is necessary to prompt the exploration of new treatment modalities. Biologic therapies, such as anti-TNF-α monoclonal antibody and JAK inhibitor, primarily consist of small molecules targeting specific pathways, effectively inducing and maintaining remission. Given the significant role of the gut microbiota, research into intestinal microecologics, such as probiotics and prebiotics, and fecal microbiota transplantation (FMT) shows promising potential in UC treatment. Additionally, medicinal herbs, such as chili pepper and turmeric, used in complementary therapy have shown promising results in UC management. This article reviews recent findings on the mechanisms of UC, including genetic susceptibility, immune cell dynamics and cytokine regulation, and gut microbiota alterations. It also discusses current applications of biologic therapy, herbal therapy, microecologics, and FMT, along with their prospects and challenges.

Sweet pepper extract reduces fat storage in Caenorhabditis elegans by SREBP-SCD axis based on multiomics analysis

Sweet pepper, a globally commercialized horticultural crop, has been demonstrated to impede fat accumulation, but its mechanism remains incompletely understood. This study was designed to explore the potential mechanism of sweet pepper in reducing fat accumulation in Caenorhabditis elegans through RNA-seq and metabolome analysis. A total of 22 metabolites were identified from sweet pepper by UHPLC-ESI-TOF-MS analysis. In vivo, sweet pepper significantly inhibited α-glucosidase activity and reduced the levels of glucose, triglycerides (TG), total cholesterol (TC), and the area stained with oil red O. Additionally, it increased body length and the number of head swings in C. elegans compared to the control group. The KEGG enrichment analysis revealed significant enrichment of the biosynthesis of unsaturated fatty acids signaling pathway among the differentially expressed genes and metabolites. Furthermore, the mRNA levels of sterol regulatory element-binding proteins (SREBPs) ortholog SBP-1, as well as the stearyl CoA desaturase-1 (SCD1), including fat-5, fat-6, and fat-7, were significantly decreased after treatment with sweet pepper. Collectively, sweet pepper effectively reduces fat accumulation, which is probably related to downregulating the SREBP-SCD axis, offering new insights for future functional food development.

Multiple effects of spicy flavors on neurological diseases through the intervention of TRPV1: a critical review

The spicy properties of foods are contributed by various spicy flavor substances (SFs) such as capsaicin, piperine, and allicin. Beyond their distinctive sensory characteristics, SFs also influence health conditions and numerous studies have associated spicy flavors with disease treatment. In this review, we enumerate different types of SFs and describe their role in food processing, with a specific emphasis on critically examining their influence on human wellness. Particularly, detailed insights into the mechanisms through which SFs enhance physiological balance and alleviate neurological diseases are provided, and a systematic analysis of the significance of transient receptor potential vanilloid type-1 (TRPV1) in regulating metabolism and nervous system homeostasis is presented. Moreover, enhancing the accessibility and utilization of SFs can potentially amplify the physiological effects. This review aims to provide compelling evidence for the integration of food flavor and human health.

Association between Variants of the TRPV1 Gene and Body Composition in Sub-Saharan Africans

In humans, the transient receptor potential vanilloid 1 (TRPV1) gene is activated by exogenous (e.g., high temperatures, irritating compounds such as capsaicin) and endogenous (e.g., endocannabinoids, inflammatory factors, fatty acid metabolites, low pH) stimuli. It has been shown to be involved in several processes including nociception, thermosensation, and energy homeostasis. In this study, we investigated the association between TRPV1 gene variants, sensory perception (to capsaicin and PROP), and body composition (BMI and bioimpedance variables) in human populations. By comparing sequences deposited in worldwide databases, we identified two haplotype blocks (herein referred to as H1 and H2) that show strong stabilizing selection signals (MAF approaching 0.50, Tajima's D > +4.5) only in individuals with sub-Saharan African ancestry. We therefore studied the genetic variants of these two regions in 46 volunteers of sub-Saharan descent and 45 Italian volunteers (both sexes). Linear regression analyses showed significant associations between TRPV1 diplotypes and body composition, but not with capsaicin perception. Specifically, in African women carrying the H1-b and H2-b haplotypes, a higher percentage of fat mass and lower extracellular fluid retention was observed, whereas no significant association was found in men. Our results suggest the possible action of sex-driven balancing selection at the non-coding sequences of the TRPV1 gene, with adaptive effects on water balance and lipid deposition.

Are We Ready to Recommend Capsaicin for Disorders Other Than Neuropathic Pain?

Capsaicin, a lipophilic, volatile compound, is responsible for the pungent properties of chili peppers. In recent years, a significant increase in investigations into its properties has allowed the production of new formulations and the development of tools with biotechnological, diagnostic, and potential therapeutic applications. Most of these studies show beneficial effects, improving antioxidant and anti-inflammatory status, inducing thermogenesis, and reducing white adipose tissue. Other mechanisms, including reducing food intake and improving intestinal dysbiosis, are also described. In this way, the possible clinical application of such compound is expanding every year. This opinion article aims to provide a synthesis of recent findings regarding the mechanisms by which capsaicin participates in the control of non-communicable diseases such as obesity, diabetes, and dyslipidemia.

Effects of Capsaicin on Glucose Uptake and Consumption in Hepatocytes

Obesity represents a major health challenge because it substantially increases the risk of metabolic diseases. Capsaicin, the major active ingredient of Capsicum spp., has been reported to possess anti-obesity activity. Hereon, the effect of capsaicin on glucose uptake and consumption in hepatocytes was extensively studied. Capsaicin was shown to accelerate the glucose uptake/consumption and the ATP production of hepatocytes. The elevation of intracellular Ca²⁺ was thought to be a potential mechanism. By transcriptome analysis, 78, 146 and 507 differentially expressed genes (DEGs) were identified between capsaicin and the control group for 4 h, 12 h and 24 h treatments. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that most of the DEGs were involved in canonical pathways, like MAPK and PI3K-AKT signaling pathways. Clustering analysis showed that many DEGs were associated with glucose and amino acid metabolism. The variation trend in genes related to glucose and amino acid metabolism (like CTH, VEGFA, PCK2 and IGFBP3) in the quantitative PCR (q-PCR) assay was consistent with the transcriptome data. These results demonstrated that capsaicin efficiently accelerated the glucose uptake and consumption of hepatocytes.

Potential benefits of spicy food consumption on cardiovascular outcomes in patients with diabetes: A cohort study of the China Kadoorie Biobank

OBJECTIVES

Dietary capsaicin from spicy foods has potential benefits for those with cardiometabolic diseases (CMDs). However, there is no evidence linking spicy food consumption with cardiovascular outcomes in individuals with diabetes. The aim of this study was to explore the association between spicy food consumption and the incidence of major adverse cardiovascular events (MACEs) in individuals with diabetes from the CKB (China Kadoorie Biobank) study and to provide evidence-based dietary recommendations for those with CMDs.

METHODS

This prospective study enrolled 26 163 patients with diabetes without coronary heart disease, stroke, or cancer from the CKB study. Of the 26 163 patients enrolled, 17 326 never or rarely ate spicy food (non-spicy group), and 8837 ate spicy food ≥1 d/wk (spicy group). The primary outcomes were MACEs, including cardiac death, non-fatal myocardial infarction, and stroke. Cox proportional hazards models were used to estimate the hazard ratio (HR) of MACEs and their associated 95% confidence intervals (CIs).

RESULTS

During a median follow-up of 8.5 y, MACEs occurred in 5465 participants (20.9%), with 3820 (22%) and 1645 (18.6%) cases occurring in the non-spicy and spicy groups, respectively. Spicy food consumption was independently associated with a decreased tendency for MACEs, with an adjusted HR of 0.94 (95% CI, 0.89-1.00; P = 0.041). Subgroup analysis showed consistency in the results that the regular spicy eating groups were associated with significantly lower incidence of MACEs than the non-spicy group. There was no statistical difference in the incidence of MACEs among the three different spicy eating frequency groups.

CONCLUSION

This cohort study revealed that the consumption of spicy food was independently associated with a reduced incidence of adverse cardiovascular events in Chinese adults with diabetes, suggesting a beneficial effect on cardiovascular health. Further studies are needed to confirm the association between the consumption of different doses of spicy food and cardiovascular outcomes and the exact mechanism of action.

Improving the Leavening Effect of Ice like CO2 Gas Hydrates by Addition of Gelling Agents in Wheat Bread

This article brings together the application of ice-like CO2 gas hydrates (GH) as a leavening agent in wheat bread along with the incorporation of some natural gelling agents or flour improvers into the bread to enhance the textural properties of the wheat bread. The gelling agents used for the study were ascorbic acid (AC), egg white (EW), and rice flour (RF). These gelling agents were added to the GH bread containing different amounts of GH (40, 60, and 70% GH). Moreover, a combination of these gelling agents in a wheat GH bread recipe was studied for each respective percentage of GH. The combinations of gelling agents used in the GH bread were as follows: (1) AC, (2) RF + EW, and (3) RF + EW + AC. The best combination of GH wheat bread was 70% GH + AC + EW + RF combination. The primary goal of this research is to gain a better understanding of the complex bread dough created by CO2 GH and its influence on product quality when certain gelling agents are added to the dough. Moreover, the prospect of managing and modifying wheat bread attributes by the use of CO2 GH with the addition of natural gelling agents has not yet been researched and is a fresh idea in the food industry.

Transient receptor potential vanilloid 1 (TRPV1)-independent actions of capsaicin on cellular excitability and ion transport

Capsaicin is a naturally occurring alkaloid derived from chili pepper that is responsible for its hot pungent taste. Capsaicin is known to exert multiple pharmacological actions, including analgesia, anticancer, anti-inflammatory, antiobesity, and antioxidant effects. The transient receptor potential vanilloid subfamily member 1 (TRPV1) is the main receptor mediating the majority of the capsaicin effects. However, numerous studies suggest that the TRPV1 receptor is not the only target for capsaicin. An increasing number of studies indicates that capsaicin, at low to mid µM ranges, not only indirectly through TRPV1-mediated Ca²⁺ increases, but also directly modulates the functions of voltage-gated Na⁺ , K⁺ , and Ca²⁺ channels, as well as ligand-gated ion channels and other ion transporters and enzymes involved in cellular excitability. These TRPV1-independent effects are mediated by alterations of the biophysical properties of the lipid membrane and subsequent modulation of the functional properties of ion channels and by direct binding of capsaicin to the channels. The present study, for the first time, systematically categorizes this diverse range of non-TRPV1 targets and discusses cellular and molecular mechanisms mediating TRPV1-independent effects of capsaicin in excitable, as well as nonexcitable cells.

Regulation of transient receptor potential channels by traditional Chinese medicines and their active ingredients

In recent years, activation of thermal transient receptor potential (TRP) ion channels at a range of temperatures has received widespread attention as a target for traditional Chinese medicine (TCM) to regulate body temperature and relieve pain. Discovery of transient receptor potential vanilloid 1 (TRPV1) was awarded a Nobel Prize, reflecting the importance of these channels. Here, the regulatory effects of TCMs and their active ingredients on TRP ion channels are reviewed, and future directions for research on the cold, hot, warm, cool, and neutral natures of TCMs are considered. In herbs with cold, hot, warm, cool, and neutral natures, we found 29 TCMs with regulatory effects on TRP ion channels, including Cinnamomi Cortex, Capsici Fructus, Rhei Radix et Rhizoma, Macleayae cordatae Herba, Menthae Haplocalycis Herba, and Rhodiolae Crenulatae Radix et Rhizoma. Although some progress has been made in understanding the regulation of TRP ion channels by TCMs and their ingredients, the molecular mechanism by which TCMs have this effect remains to be further studied. We hope this review will provide a reference for further research on the cold, hot, warm, cool, and neutral natures of TCMs.

Dietary Supplements for Weight Management: A Narrative Review of Safety and Metabolic Health Benefits

Dietary supplements for weight management include myriad ingredients with thermogenic, lipotropic, satiety, and other metabolic effects. Recently, the safety of this product category has been questioned. In this review, we summarize the safety evidence as well as relevant clinical findings on weight management and metabolic effects of six representative dietary supplement ingredients: caffeine, green tea extract (GTE), green coffee bean extract (GCBE), choline, glucomannan, and capsaicinoids and capsinoids. Of these, caffeine, GTE (specifically epigallocatechin gallate [EGCG]), and choline have recommended intake limits, which appear not to be exceeded when used according to manufacturers’ instructions. Serious adverse events from supplements with these ingredients are rare and typically involve unusually high intakes. As with any dietary component, the potential for gastrointestinal intolerance, as well as possible interactions with concomitant medications/supplements exist, and the health status of the consumer should be considered when consuming these components. Most of the ingredients reviewed also improved markers of metabolic health, such as glucose, lipids, and blood pressure, although the data are limited for some. In summary, weight management supplements containing caffeine, GTE, GCBE, choline, glucomannan, and capsaicinoids and capsinoids are generally safe when taken as directed and demonstrate metabolic health benefits for overweight and obese people.