Analysis of annual publication trends
The predefined WoSCC search strategy and database filters yielded a total of 2,473 records, which constituted the final dataset for bibliometric analysis. From 2015 to 2025, the annual number of publications in this field showed an overall upward trend, increasing from 72 publications in 2015 to 333 publications in 2025. The publication output increased steadily between 2015 and 2018, followed by a rapid growth phase from 2019 to 2021, reaching a peak in 2021 (334 publications). Although annual publication output showed some variation in recent years, overall productivity remained robust. The sustained high level of publications indicates that research on gut microbiota and metabolic syndrome has entered a mature phase of development, highlighting its continued importance within the scientific community (Figure 2).
Analysis of country distribution and collaboration networks
Figure 3A presents the geographical visualization of international collaborations, revealing a clear globalized research pattern in this field. China and the United States were identified as the major research centers, with the highest publication outputs, the largest node sizes, and the strongest collaborative relationship between the two countries. European countries, including the United Kingdom, Spain, Italy, and Denmark, demonstrated close collaborative connections, forming relatively stable regional cooperation networks. In addition, China maintained extensive collaborations with countries such as India and Australia. Overall, an international collaboration framework centered on China and the United States, with broad participation from multiple countries, has been established in this field.
The CiteSpace country collaboration network shown in Figure 3B comprised 97 nodes and 134 links, with a density of 0.0288, reflecting an established but relatively sparse international collaboration network. China and the United States had the highest publication outputs and the largest node sizes, occupying the core positions within the collaboration network. In terms of betweenness centrality, the United States exhibited a prominent intermediary role, serving as a key bridge in international academic collaborations. Although China demonstrated a high publication volume, its centrality was relatively lower, indicating a less prominent bridging role within the international collaboration network. In addition, European countries, such as Italy, Spain, and the Netherlands, showed strong interconnections and formed regional collaboration networks. Collectively, these findings indicate that the field has developed an international collaborative landscape centered on China and the United States, with extensive participation from multiple countries.
Institutional collaboration network analysis
Figure 3C illustrates the institutional collaboration network, demonstrating extensive inter-institutional collaborations in this field. The size of each node represents the publication output of the institution, while the connecting lines indicate collaborative relationships and their strengths. Overall, the institutions were closely interconnected, forming a prominent collaborative network structure. Among them, Instituto de Salud Carlos III had the highest publication output and occupied a central position within the network, maintaining close collaborations with multiple institutions. Zhejiang University, Harvard Medical School, and the Chinese Academy of Sciences also showed high publication outputs and represented major research contributors in this field. In terms of collaboration patterns, the core institutions formed relatively stable cooperation networks, indicating that a mature institutional collaboration model has gradually been established in this research area.
Keyword analysis
Analysis of keyword hotspots and evolution trends
The keyword co-occurrence analysis (Figure 4A) demonstrated that “metabolic syndrome” and “gut microbiota” constituted the central nodes of the research network. Other high-frequency keywords included “obesity,” “inflammation,” and “insulin resistance,” indicating that the major research focuses were metabolic disorders, inflammatory responses, and gut microecological regulation. The keyword density map (Figure 4B) further revealed that the regions centered around “metabolic syndrome” and “gut microbiota” exhibited the highest density, surrounded by highly frequent terms such as “obesity” and “inflammation,” thereby forming distinct research hotspot clusters. In addition, several related research directions, including “gut microbiota,” “probiotics,” and “nonalcoholic steatohepatitis,” extended from these core themes, reflecting a multi-layered research structure.
The keyword network encompassed both mechanistic and intervention-related research. Terms such as “high-fat diet,” “mice,” and “intestinal permeability” reflected investigations into the mechanisms linking gut microbiota to metabolic disturbances, while “probiotics,” “Mediterranean diet,” and “double-blind” indicated the inclusion of dietary interventions and clinical study designs. Together, these findings illustrated a broad research scope encompassing mechanistic investigation and potential clinical applications.
Analysis of keyword bursts and emerging research trends
The keyword burst analysis (Figure 4C) revealed distinct evolutionary characteristics of research frontiers across different periods. During the early stage (2015–2019), burst keywords mainly included “diet induced obesity,” “induced insulin resistance,” “fecal microbiota,” and “innate immunity,” with relatively high burst strengths (e.g., “diet induced obesity,” strength = 9.02), indicating that research during this period primarily focused on obesity-related metabolic abnormalities and fundamental immune mechanisms.
During the intermediate stage (2017–2021), research hotspots gradually shifted toward terms such as “glucose tolerance,” “endothelial dysfunction,” and “metagenome,” reflecting increasing attention to metabolic functions and molecular-level mechanisms. In recent years (2021–2025), burst keywords have mainly included “protein,” “cells,” “pathway,” “supplementation,” and “fructose,” suggesting that current research frontiers have evolved from studies of basic metabolism and phenotypes toward molecular mechanism exploration and intervention strategy development.
Overall, the research hotspots in this field have undergone a progressive evolution from metabolic phenotype investigations to molecular mechanism elucidation, and subsequently toward clinical translation and intervention applications. With the continuous deepening of molecular mechanistic studies, research limited solely to mechanistic exploration can no longer fully satisfy current scientific demands. Consequently, increasing emphasis has been placed on the clinical translation and practical application of basic research findings, highlighting the clinical value of gut microbiota-related mechanisms in precision therapy, individualized intervention, and disease management.
Analysis of author collaboration networks
The author collaboration network (authors with ≥3 publications) is presented in Figure 5A, showing that multiple relatively independent research teams have been established in this field. Node size represents the publication output of authors, while connecting lines indicate collaborative relationships between authors. Different colors represent distinct collaboration clusters. Among all authors, Nieuwdorp M had the highest publication output and occupied a central position within the network, maintaining collaborative relationships with multiple research groups. Authors such as Chassaing B, Moreno-Indias I, Portincasa P, and Gasbarrini A also demonstrated relatively high publication outputs and formed several major research clusters. From the network structure, collaborations within individual author clusters were relatively close, whereas interactions between different clusters were comparatively limited, suggesting that a highly integrated global author collaboration network has not yet been fully established in this field.
Analysis of author co-citation networks
The author co-citation network (authors cited at least 30 times; Figure 5B) indicates the establishment of a stable knowledge base in this field. Node size represents citation frequency, while connecting lines indicate co-citation relationships between authors. Various colors represent unique research theme clusters. Cani PD demonstrated the highest co-citation frequency and largest node size, indicating a prominent position within the author co-citation network. Authors such as Alberti KGMM, Saklayen MG, and Caporaso JG also showed high co-citation frequencies and constituted important foundational contributors to this research area.
From the clustering structure, author groups with different colors represented distinct research directions, including the definition and clinical research of metabolic syndrome, gut microbiota structural analysis and sequencing technologies, as well as studies on gut microbiota and metabolic mechanisms. The observed links among clusters reflect considerable thematic convergence and intellectual exchange between different lines of research.
The journal distribution and co-occurrence analysis (journals with ≥5 publications; Figure 6A) revealed a predominance of publications appearing in journals focusing on nutrition and related disciplines, metabolism, and microbiology. Node size represents the publication output of journals, while connecting lines indicate co-occurrence relationships between journals. Different colors represent distinct research directions. Among all journals, Nutrients exhibited the largest node size and the highest publication output, making it the leading journal in this field. International Journal of Molecular Sciences, Frontiers in Nutrition, and Food & Function also showed relatively high publication outputs, collectively constituting the core journal cluster.
From the clustering structure, the journals could generally be categorized into three major research directions. One cluster mainly focused on nutrition and food science, including journals such as Nutrients and Food & Function; another cluster emphasized molecular mechanisms and microbiology, represented by International Journal of Molecular Sciences; and the third cluster primarily concentrated on clinical and metabolic disease research, represented by journals such as Frontiers in Endocrinology.
In addition, the core journals with ≥5 publications and their impact indicators are summarized in Table 2. Other frequently represented journals included Nutrients, International Journal of Molecular Sciences, Frontiers in Nutrition, and Food & Function. Most core journals were classified in the upper Journal Citation Reports (JCR) quartiles and had relatively high impact factors, indicating that research in this field has been published across several highly ranked journals. The journal co-occurrence network further demonstrated that studies related to gut microbiota and metabolic syndrome are mainly published in the disciplines of nutrition, metabolism, and microbiology, highlighting the strong interdisciplinary characteristics of this research area.
Co-cited reference network analysis
Figure 6B presents the co-cited reference network, which exhibited a clear clustering pattern. Node size represents citation frequency, connecting lines indicate co-citation relationships, and different colors represent distinct research clusters. The network comprised four primary research clusters. The blue cluster (core foundational research), represented by studies such as Turnbaugh PJ (2006, Nature) and Cani PD (2007, Diabetes), primarily focused on the fundamental mechanisms linking gut microbiota with obesity and metabolic disorders, thereby constituting the theoretical foundation of this field. The green cluster (mechanisms and metabolic regulation), represented by Qin J (2012, Nature) and David LA (2014, Nature), mainly focused on microbiome structure, metabolic pathways, and the interaction mechanisms between gut microbiota and the host. The red cluster (reviews and frontier integration), represented by Saklayen MG (2018) and Fan Y (2021), mainly consisted of review studies related to metabolic syndrome and gut microbiota, reflecting knowledge integration and emerging developmental directions within the field. The yellow cluster (clinical studies and disease associations), represented by Zhu L (2013, Hepatology) and Younossi ZM (2016), primarily involved clinical research associated with MASLD, liver diseases, and related metabolic disorders.
Among all references, Turnbaugh PJ (2006) and Cani PD (2007) exhibited the largest node sizes and the densest connections, highlighting their central hub positions within the network and their foundational importance for subsequent studies. In terms of network connectivity, the green and blue clusters showed the closest relationships, suggesting a high degree of integration between foundational and mechanistic research. In contrast, the red and yellow clusters were more peripheral and primarily represented reviews and clinical studies, respectively.
Analysis of research theme evolution
Combined with the results of the co-cited reference network and keyword evolution analyses, the research themes in this field showed a broadening of research emphasis, with clinical translation and comprehensive intervention strategies gaining prominence alongside continued mechanistic research. At the beginning of the observation period, scientific attention was primarily directed toward understanding how alterations in gut microbial communities were associated with obesity-related metabolic dysfunction. Major research themes involved diet-induced obesity, impaired insulin sensitivity, and innate immune responses, highlighting efforts to clarify the biological pathways underlying metabolic disorders.
Subsequently, research gradually expanded toward metabolic pathways and host–microbiota interaction mechanisms, with increasing attention to short-chain fatty acids, bile acid metabolism, intestinal barrier function, and inflammatory signaling pathways. During this period, studies employing multi-omics technologies and metagenomic approaches also increased substantially.
In recent years, research hotspots have increasingly included clinical translation and intervention strategies, including probiotics, dietary nutrition, individualized therapies, and metabolic dysfunction-associated steatotic liver disease. Notably, burst keywords such as “pathway,” “supplementation,” and “fructose” have persisted through 2025, suggesting that current research is increasingly focused on elucidating mechanistic pathways and the clinical value of nutritional interventions.
DATA AVAILABILITY:
The datasets analyzed during the current study are publicly available from the WoSCC database. All data generated or analyzed during this study are available from the corresponding author upon reasonable request.

Figure 1: Flowchart of literature retrieval and dataset construction. This figure summarizes the literature retrieval, data processing, bibliometric analysis, and visualization workflow used in this study. Please click here to view a larger version of this figure.

Figure 2: Annual publication output in gut microbiota and metabolic syndrome research from 2015 to 2025. This figure illustrates the yearly publication volume and the overall growth trend of research in this field from 2015 to 2025. Please click here to view a larger version of this figure.

Figure 3: Geographic distribution and collaboration networks in gut microbiota and metabolic syndrome research from 2015 to 2025. (A) Geographic visualization of international collaborations among countries generated using SCImago Graphica. (B) Country-level collaboration network. Nodes represent countries, node size indicates publication output, connecting lines represent collaborative relationships, and node and link colors correspond to the annual time slices from 2015 to 2025. (C) Institutional collaboration network. Node size represents institutional publication output, connecting lines indicate inter-institutional collaborations, and thicker lines represent stronger collaborative relationships. Please click here to view a larger version of this figure.

Figure 4: Keyword co-occurrence, density, and burst analyses in gut microbiota and metabolic syndrome research. (A) Overlay visualization of keyword co-occurrence. Node size represents keyword occurrence frequency, connecting lines indicate co-occurrence relationships, and colors represent the average publication year of the documents in which each keyword occurred, with blue indicating earlier average publication years and yellow indicating more recent average publication years. (B) Keyword density visualization. The color gradient from blue to red indicates increasing keyword occurrence frequency, with red regions representing concentrated research hotspots. (C) Keyword burst analysis. Red bars indicate periods of burst activity, and burst strength reflects the intensity of the research trend. Please click here to view a larger version of this figure.

Figure 5: Author collaboration and co-citation networks in gut microbiota and metabolic syndrome research. (A) Collaboration network of authors with three or more publications. Node size represents author publication output, connecting lines indicate collaborative relationships, and colors represent distinct collaboration clusters. (B) Author co-citation network for authors with at least 30 citations. Node size represents author co-citation frequency, connecting lines indicate co-citation relationships, and colors represent distinct co-citation clusters. Please click here to view a larger version of this figure.

Figure 6: Journal and reference networks in gut microbiota and metabolic syndrome research. (A) Co-occurrence network of journals with at least five publications. Node size represents journal publication output, connecting lines indicate relationships between journals, and colors represent distinct research clusters. (B) Co-cited reference network. Node size represents citation frequency, connecting lines indicate co-citation relationships among references, and colors represent distinct research clusters. Please click here to view a larger version of this figure.
| Clinical Trial Identifier | Study Status | Indications | Intervention | Key Primary Outcome Measures | Key Secondary/Other Outcome Measures | Representative Category |
| NCT02041104 | Completed | Metabolic Syndrome; Dyslipidemia; Abdominal Obesity; Hyperglycemia; Hypertension | Bread with added β-glucans vs. bread without added β-glucans | Lipid profile, intestinal microbiota composition, OGTT-based glucose and insulin measures, blood pressure, and fecal SCFAs | Post-intervention intestinal microbiota composition, SCFAs, lipid profile, and glucose/insulin responses | Dietary/prebiotic-related intervention |
| NCT03201068 | Completed | Metabolic Syndrome; Microbiome; Immune Function; Inflammation | Probiotic supplement vs. placebo | Changes in metabolic syndrome parameters, including waist circumference, blood pressure, triglycerides, HDL-cholesterol, and fasting glucose | Microbiota composition, microbiota metabolites/SCFAs, cytokines, chemokines, and hs-CRP | Probiotic supplementation |
| NCT03477916 | Completed | Obesity; Metabolic Syndrome | Fecal microbiota transplantation (FMT) and/or prebiotic fiber supplementation | Change in insulin sensitivity | BMI and body weight, glucose metabolism, lipid profile, blood pressure, quality of life, inflammatory markers, stool microbiota composition, and SCFAs | FMT + prebiotic fiber |
| NCT03608800 | Completed | Metabolic Syndrome | Intermittent fasting vs. control diet | BMI and body fat mass | Blood pressure, gut microbiota composition and metabolic pathways, inflammatory and vascular biomarkers, and glucose/lipid-related measures | Dietary/lifestyle intervention |
Table 1: Representative ClinicalTrials.gov studies of gut microbiota-related interventions in metabolic syndrome. This table summarizes representative interventional studies covering distinct gut microbiota-related intervention strategies in metabolic syndrome.
| No. | Journal Title | Journal Impact Factor (2024) | JCR Category/Quartile (2024) |
| 1 | Nutrients | 5 | Nutrition & Dietetics, Q1 |
| 2 | International Journal of Molecular Sciences | 4.9 | Biochemistry & Molecular Biology, Q1 |
| 3 | Frontiers in Nutrition | 5.1 | Nutrition & Dietetics, Q1 |
| 4 | Food & Function | 5.4 | Food Science & Technology, Q1 |
| 5 | Frontiers in Endocrinology | 4.6 | Endocrinology & Metabolism, Q1 |
| 6 | Nutrition & Metabolism | 4.1 | Nutrition & Dietetics, Q2 |
| 7 | Clinical Nutrition | 7.4 | Nutrition & Dietetics, Q1 |
| 8 | Advances in Nutrition | 9.2 | Nutrition & Dietetics, Q1 |
| 9 | International Journal of Biological Macromolecules | 8.5 | Biochemistry & Molecular Biology, Q1 |
| 10 | LWT - Food Science and Technology | 6.6 | Food Science & Technology, Q1 |
Table 2: Core journals and their impact indicators. This table summarizes the core journals identified in the analysis and their corresponding impact indicators. Journal impact factors and JCR quartiles are reported for the 2024 metric year.
| First Author | Year | Journal | Main Research Content | IF |
| Turnbaugh PJ | 2006 | Nature | Proposed the concept of obesity-associated gut microbiota | 48.5 |
| Cani PD | 2007 | Diabetes | Proposed the theory of metabolic endotoxemia | 7.5 |
| Qin J | 2012 | Nature | Metagenomic analysis of gut microbiota composition in patients with type 2 diabetes mellitus | 48.5 |
| David LA | 2014 | Nature | Investigated the effects of diet on dynamic alterations in gut microbiota composition | 48.5 |
| Fan Y | 2021 | Nat Rev Microbiol | Summarized the relationship between gut microbiota and metabolic diseases | 103.3 |
| Heianza Y | 2023 | Nat Rev Endocrinol | Reviewed the relationship between microbiota-derived metabolites and cardiometabolic diseases | 42.3 |
Table 3: Main contents and contributions of core references cited more than five times. This table summarizes the main research content and key contributions of the core references cited more than five times.
Supplementary File 1: Search syntax. This file provides the complete search syntax for the current study.Please click here to download this file.