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Korean fermented soybean pastes (jang, including doenjang, ganjang, and gochujang) and jeotgal are characterized by their complex microbial ecosystems, rich nutrient composition, and notable health-promoting properties. These foods naturally generate bioactive metabolites such as isoflavones, γ-polyglutamic acid, phenolic acids, and peptides, which contribute to antioxidant, anti-inflammatory, anti-cancer, and menopausal symptom-alleviating effects. Unlike standardized industrial products, traditional fermentation relies on spontaneous microbial interactions and extended maturation, resulting in distinctive metabolite profiles and enhanced functional activity. Recent advances in metabolomics have enabled comprehensive characterization of these metabolites through both targeted and untargeted approaches, offering insights into fermentation dynamics, nutritional quality, and functional potential. Comparative metabolomic studies reveal that traditionally fermented soybean pastes and jeotgal exhibit greater chemical diversity and bioactivity compared with their commercial counterparts, emphasizing both their scientific and cultural value. This review synthesizes current evidence on the nutritional and functional attributes of these foods, with a focus on metabolomic methodologies that elucidate key metabolic pathways and their physiological relevance. In addition, it highlights the industrial potential of fermentation-derived bioactive compounds, while emphasizing the need for integrative multi-omics strategies, including genomics and metagenomics, to understand complex microbe–host–metabolite interactions. Such approaches can deepen understanding of how fermentation-derived metabolites contribute to host health, gut microbiota modulation, and disease prevention. By consolidating nutritional, functional, and metabolomic perspectives, this review provides a focused framework for advancing the global recognition, scientific validation, and sustainable development of Korean fermented soybean pastes and jeotgal.

Catecholamines and steroids are well-known neurotransmitters and hormones that rapidly change the excitability of neurons. Alopecia areata is a disease for which the exact cause is unknown, but it is considered to be associated with stress, and so the simultaneous analysis of catecholamines and steroids is required for the diagnosis of alopecia areata. Thus, we herein report the simultaneous analysis of catecholamines and steroids bearing different functional groups for the first time, during which it was necessary to carry out a serial hydrolysis procedure. Following hydrolysis of the urine samples to produce the free forms from the urinary conjugates, ethyl acetate extractions were carried out, and chemical derivatization was performed using dansyl chloride to increase the sensitivity of the liquid chromatography–tandem mass spectrometry method. The matrix effects and recoveries of this analytical method were validated, giving values of 85.4–122.9% and 88.8–123.0%, respectively. In addition, the method accuracy and precision were assessed, giving values of 0.4–21.5% and 2.0–21.6% for the intra-day and inter-day precisions, respectively. This validated method was then applied to identify differences between patients with and without alopecia areata, wherein the metanephrine content was found to be significantly higher in the alopecia areata patient group. This quantitative profiling method can also be applied to steroid-dependent diseases, as well as catecholamine-related diseases.

Fusobacteria are associated with colorectal cancer (CRC) and are amplified during colorectal carcinogenesis. Compared to the adenoma-carcinoma sequence of carcinogenesis, serrated neoplasm has distinct clinical features and a different molecular background. We aimed to compare the gut microbiome between tubular adenoma (TA) and sessile serrated adenoma/polyp (SSA/P). Patients with TA, SSA/P, or CRC were recruited. Three pieces of colorectal mucosal tissue were obtained from each patient by endoscopic biopsy. 16S rRNA gene pyrosequencing and phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) were performed. Among 26 enrolled patients, 8, 10, and 8 had TA, SSA/P, and CRC, respectively. The relative abundance of Fusobacteria did not differ significantly between the TA and SSA/P groups (4.3% and 1.9%, P  = 0.739) but was higher in the CRC group (33.8%) than in the TA or SSA/P group, respectively (TA vs. CRC, P  = 0.002, false discovery rate [FDR] = 0.023; SSA/P vs. CRC, P  < 0.001, FDR = 0.001). PICRUSt revealed that most functions in the TA metagenome were similar to those in the SSA/P metagenome. The gut microbiome, including relative abundance of Fusobacteria , did not differ between TA and SSA/P, suggesting that Fusobacteria may contribute to both the serrated pathway and the adenoma-carcinoma sequence.

A simultaneous quantitative profiling method for polyamines and steroids using liquid chromatography–tandem mass spectrometry was developed and validated. We applied this method to human serum samples to simultaneously evaluate polyamine and steroid levels. Chemical derivatization was performed using isobutyl chloroformate to increase the sensitivity of polyamines. The method was validated, and the matrix effects were in the range of 78.7–126.3% and recoveries were in the range of 87.8–123.6%. Moreover, the intra-day accuracy and precision were in the ranges of 86.5–116.2% and 0.6–21.8%, respectively, whereas the inter-day accuracy and precision were in the ranges of 82.0–119.3% and 0.3–20.2%, respectively. The linearity was greater than 0.99. The validated method was used to investigate the differences in polyamine and steroid levels between treated breast cancer patients and normal controls. In our results, N-acetyl putrescine, N-acetyl spermidine, cadaverine, 1,3-diaminopropane, and epitestosterone were significantly higher in the breast cancer patient group. Through receiver operating characteristic curve analysis, all metabolites that were significantly increased in patient groups with areas under the curve >0.8 were shown. This mass spectrometry-based quantitative profiling method, used for the investigation of breast cancer, is also applicable to androgen-dependent diseases and polyamine-related diseases.

Background: Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease. In recent times, the term NAFLD has been modified to metabolic dysfunction-associated steatotic liver disease (MASLD), reflecting its comprehensive scope encompassing a range of metabolic abnormalities. Coriandrum sativum L. (CS) is a traditional medicine, although the preventive mechanism of CS extracts remains unclear. Objective: This study evaluated the preventive effects of CS in high-fat diet (HFD)-induced MASLD mice by oral administration of 100 or 200 mg/kg/day of CS extracts for 12 weeks. Results: The major CS extract compounds were chlorogenic acid, caffeic acid, rutin, and isoquercetin. The administration of CS extract suppressed HFD-induced weight gain, liver weight, and the liver/body weight ratio. It improved the mice’s serum biological profiles and suppressed HFD-induced lipid droplet and lipid accumulation by inhibiting lipid accumulation-related gene expression in the liver. It modulated HFD-induced Ampk-Srebp1c pathways and suppressed HFD-induced NF-κB pathway activation in the liver. It regulated inflammation and the AMPK alpha signaling pathway in HFD-fed mice by reducing the accumulation of specific amino acids, leading to the amelioration of fatty liver. Conclusions: The CS extract prevents HFD-induced MASLD and may help prevent or treat MASLD.

Prolonged intake of a high-fat diet (HFD) disturbs the composition of gut microbiota, contributing to the development of metabolic diseases, notably obesity and increased intestinal permeability. Thyme (Thymus vulgaris L.), an aromatic plant, is known for its several therapeutic properties. In this study, we explored the potential of thyme extract (TLE) to mitigate HFD-induced metabolic derangements and improve the gut environment. Eight-week-old C57BL/6 mice were administered 50 or 100 mg/kg TLE for eight weeks. Administration of 100 mg/kg TLE resulted in decreased weight gain and body fat percentage, alongside the regulation of serum biomarkers linked to obesity induced by a HFD. Moreover, TLE enhanced intestinal barrier function by increasing the expression of tight junction proteins and ameliorated colon shortening. TLE also altered the levels of various metabolites. Especially, when compared with a HFD, it was confirmed that 2-hydroxypalmitic acid and 3-indoleacrylic acid returned to normal levels after TLE treatment. Additionally, we investigated the correlation between fecal metabolites and metabolic parameters; deoxycholic acid displayed a positive correlation with most parameters, except for colon length. In contrast, hypoxanthine was negatively correlated with most parameters. These results suggest a promising role for thyme in ameliorating obesity and related gut conditions associated with a HFD.

Non-alcoholic fatty liver disease (NAFLD) is a major issue because it is closely associated with metabolic diseases. Advanced glycation end products (AGEs) are implicated as risk factors for steatosis during NAFLD progression. AGEs influence NAFLD progression through a receptor-independent pathway involving AGE cross-link formation and a receptor-dependent pathway that binds to receptors like receptors for advanced glycation end products (RAGE). The objectives of this study are to examine the effect of Lindera obtusiloba Blume (LO) on NAFLD promoted by Nε-(carboxymethyl)lysine (CML), one of the most common dietary AGEs. The anti-glycation effects of LO were evaluated by inhibiting the AGEs formation and AGEs-collagen cross-links breaking. The efficacy of LO against NAFLD promoted by CML was assessed using both in vitro and in vivo models. NAFLD was induced in mice by feeding a high-fat diet and orally administering CML over a period of 12 weeks, and the effects of LO on lipid metabolism and its regulatory mechanisms were investigated. LO showed the effect of inhibited AGEs formation and breakage, and collagen cross-linking. Fed a high-fat diet with administered CML by gavage, LO administration resulted in a reduction in body weight, fat mass, serum triglycerides, total cholesterol, and low-density lipoprotein cholesterol levels. LO reduced hepatic CML accumulation and RAGE expression in mice fed a high-fat diet and orally administered CML. LO alleviated hepatic steatosis accompanied by lipid accumulation and histological damage by suppressing the expression of sterol regulatory element-binding protein 1c, carbohydrate response element binding protein, fatty acid synthase, stearoyl-CoA desaturase1, tumor necrosis factor-α, and interleukin-1β. LO alleviated the MAPK/NF-κB expression by attenuating CML and RAGE expression. Taken together, our results demonstrate that LO alleviates the progression of NAFLD by lowering the levels of AGEs by downregulating CML/RAGE expression.

Osteoarthritis is one of the leading conditions that promote the consumption of these dietary supplements. Chondroitin sulfate, glucosamine, and methylsulfonylmethane are among the prominent alternative treatments for osteoarthritis. In this study, these dietary supplements were incubated with cytochrome P450 isozyme-specific substrates in human liver microsomes, and the formation of marker metabolites was measured to investigate their inhibitory potential on cytochrome P450 enzyme activities. The results revealed no significant inhibitory effects on seven CYPs, consistent with established related research data. Therefore, these substances are anticipated to have a low potential for cytochrome P450-mediated drug interactions with osteoarthritis medications that are likely to be co-administered. However, given the previous reports of interaction cases involving glucosamine, caution is advised regarding dietary supplement–drug interactions.

With the advancement of multiomics technologies and cohort study designs, integrative omics research is increasingly applied to human health and nutrition. However, optimal storage and preprocessing of labile biological samples, particularly feces, remain challenging. In this study, we systematically evaluated three normalization methods—wet weight, dry weight, and protein quantification—for quantitative metabolomic profiling of fecal samples, using 41 metabolites. Fresh fecal samples from three healthy individuals showed high reproducibility, with 24 metabolites exhibiting a coefficient of variation (CV) below 30 for both wet and dry weight normalization. Fecal samples from 20 obese patients collected using the OMNIgene·GUT kit demonstrated improved reproducibility with wet weight normalization (20 metabolites, CV < 30) and protein quantification normalization (19 metabolites, CV < 30), whereas dry weight normalization yielded no metabolites meeting the CV < 30 criterion. Direct analysis of the kit solution without a drying step further enhanced chromatographic clarity, highlighting practical considerations for large‐scale studies. Overall, wet weight normalization consistently minimized variation across sample types, providing a robust and standardized framework for fecal metabolite profiling. These findings demonstrate that the OMNIgene·GUT kit is compatible with broad‐spectrum metabolomic analyses and support its integration into multiomics workflows. By establishing reproducible normalization protocols, this study provides the foundation for accurate, comparable, and scalable fecal metabolomics in both clinical and nutritional research settings.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a leading global liver disorder. Parsnip ( Pastinaca sativa ), rich in dietary fiber and medicinal properties, has shown health benefits, but its effects on MASLD are largely unexplored. This study evaluated the prebiotic and anti-MASLD effects of parsnip root water-soluble extract (PRE) in a mouse model. Mice fed a high-fat diet with 50 or 100 mg/kg PRE for eight weeks showed reduced fat accumulation, improved serum metabolic profiles, and decreased liver injury markers. PRE also lowered hepatic lipogenic protein levels induced by the high-fat diet. Additionally, PRE enhanced gut health by reducing endotoxins, improving intestinal permeability, and upregulating tight junction proteins. These results indicate that PRE can improve gut health, prevent MASLD, and support its potential as a dietary supplement to enhance metabolic health.