The gut microbiota (GM) comprises microorganisms, including bacteria, viruses, and fungi, which live in the digestive tract (Thursby and Juge, 2017; Chen et al., 2021). The total number of these microorganisms in the microbiota is more than 10 trillion (Witkowski et al., 2020; Ley, 2022). The primary role of the GM is to assist in the fermentation of non-digestible substrates (Valdes et al., 2018), but studies have indicated that the GM causes several diseases, including infectious diseases (Libertucci and Young, 2019), hypertension (Li et al., 2017), atherosclerosis (Ma and Li, 2018), and thrombus formation (Duttaroy, 2021). The GM releases endotoxins or metabolites that trigger the primary immune response, causing systemic inflammation (Rooks and Garrett, 2016; Brandsma et al., 2019). An appropriate balance of microorganisms in the gastrointestinal tract is necessary for the maintenance of several bodily processes, whereas an imbalance is detrimental to the host (Fujimura et al., 2010; Hasan and Yang, 2019). GM transplantation or modulation is a promising method for treating several diseases caused by GM dysbiosis (Liu et al., 2017; Settanni et al., 2021). Our knowledge of the GM has gradually increased over time (Trejo-Castro et al., 2022).

Cardiovascular disease (CVD) is one of the leading causes of death worldwide (Roth et al., 2020). The factors responsible for CVD are variable, and the mechanisms complicated. Studies in the last two decades have implicated the GM in CVD (Ordovas and Mooser, 2006). The GM has been found to be related to atherosclerosis, as bacterial DNA has been detected in atherosclerotic plaques (Koren et al., 2011). Many studies in recent decades have confirmed that the GM contributes to the pathophysiology of CVD, and understanding the underlying mechanisms could provide novel therapeutic strategies for treating CVD (He et al., 2015; Blandino et al., 2016; Li et al., 2017). Hypertension and dyslipidemia are two dominant risk factors for CVD and are related to the alteration of the GM (Li et al., 2017; Chi et al., 2019; Zwartjes et al., 2021). Metabolism-related diseases, such as type 2 diabetes and obesity, have over time become the main health burdens globally, and both of them are associated with the GM, a major factor implicated in the development of CVD (Piche et al., 2020). Further research is under way to explore the possible molecular mechanism of how the GM contributes to the incidence of CVD. Metabolites synthesized by the GM, such as choline trimethylamine/trimethylamine oxide (TMA/TMAO), promote the development of atherosclerosis/cardiorenal fibrosis by binding to amine-associated receptors (Chen et al., 2016). Lipopolysaccharide modulates vascular function via the toll-like receptors 2, 4, and 9 (Medvedev et al., 2000), and short-chain fatty acids negatively affect blood pressure via G-protein-coupled receptors 41 and 43 (Natarajan et al., 2016). More studies in this area are still under way.

Bibliometrics analysis based on VOSviewer or CiteSpace is widely used to systematically assess the achievements, hotspots, and research trends in a specific area based on the literature published in this field. Bibliometric indicators include cooperation between authors, countries, and institutions, as well as keywords and references (Rousseau, 2014). Bibliometric analysis summarizes the abundant data and findings in a specific field. In recent years, it has been widely applied in many fields of medicine, such as developing drugs for CVD (Lai et al., 2022), the role of exosomes in CVD (Ma et al., 2021), the role of signaling pathways in the development of diseases (Shi et al., 2020), and cardiac regeneration (Ma et al., 2021). Over the last two decades, more than 1,500 pieces of literature on the GM in CVD have been published. However, bibliometric analysis in this field is still lacking.

The current study summarized the most recent progress, evolutionary path, study hotspots, and potential research directions on the GM in CVD based on bibliometric analysis of publications in this field. The findings of this study could provide a strong foundation for future research and valuable insight into the role of the GM in CVD.

To the best of our knowledge, this is the first bibliometric analysis of the GM in CVD. Our findings highlight the following:

As shown in Figure 1 , only 22 (1.53%) pieces of literature were published from 2004 to 2012, and 398 (26.5%) were published from 2013 to 2018. A total of 1,077 (71.8%) pieces of literature have been published since 2019. More than 98% of publications were published in the last decade, spurred by two novel publications by Vijay-Kumar M et al. and Omry Koren et al. In 2010, Vijay-Kumar M et al. published a paper in Science titled “Metabolic syndrome and altered gut microbiota in mice lacking Toll-like receptor 5”, which was the first to reveal that the GM participates in the development of metabolic diseases. The research also indicated that dysfunction of the innate immune system promotes the development of metabolic syndrome (Vijay-Kumar et al., 2010). In early 2011, Omry Koren et al. published another paper, titled “Human oral, gut, and plaque microbiota in patients with atherosclerosis”, in Proceedings of the National Academy of Sciences of the USA. Their study showed that bacteria from the oral cavity and the gut correlate with disease markers of atherosclerosis (Koren et al., 2011). Those two papers set the pace and provided a strong foundation for research on the role of the GM in CVD. Two reviews, “The role of the gut microbiota in energy metabolism and metabolic disease” by Cani PD et al., published in Current Pharmaceutical Design in 2009 (Cani and Delzenne, 2009), and “Functional interactions between the gut microbiota and host metabolism”, by Tremaroli V et al., published in Nature in 2012 (Tremaroli and Backhed, 2012), systematically summarized the research in this field, and showed research prospects in this area. Notably, those four papers were among the top 10 most cited papers, and were published before 2013, before a rapid increase in publications in this field.

The USA and China contributed similar numbers of publications in this field, 418 (27.8%) and 485 (32.3%) publications, respectively. This indicator is highly dependent on the number of productive institutions in a country. The USA and China are leading countries in publications in this field, with three and four institutions, respectively, among the top 10 institutions with the most publications in this field. As shown in Table 3 , the Chinese Academy of Medical Sciences and Peking Union Medical College (Np: 62), the Chinese Academy of Sciences (Np: 33), Sun Yat-sen University (Np: 29), and Shanghai Jiao Tong University (Np: 27) were the four Chinese institutions in the top 10 most productive institutions in this field. The University of California System (Np: 56), Harvard University (Np: 41), and the Cleveland Clinic Foundation (Np: 27) were the three USA institutions in the top 10 fruitful institutions. China had seven of the top 10 most prolific authors, which explains its position among the top 10 fruitful countries. Furthermore, differences in the influence of the USA and China should be noted. The H-index (47) and ACN (20.1) were lower for China than for the USA (H-index: 80, ACN: 59.6). As shown in Figure 3C , China began research in this field much later than the USA, which might explain why it lags the USA. As in other fields of cardiology (Lai et al., 2017), the USA’s excellence in the scientific research system offered a strong base for high-quality research. Knight R, who is from the USA, has cooperated widely with other authors, which further underlines the great influence of the USA in this area of study ( Figure 4 ). The huge variety of the GM and the complexity of the mechanisms linking the GM and CVD make research in this field difficult (Rahman et al., 2022). Cooperation between different groups or institutions is necessary if the hidden mechanisms are to be determined. The number of publications from China has increased hugely in the last 8 years, from 1 in 2014 to 136 in 2021. In the first 9 months of 2022, the number of publications from China was 130, and the total number of publications in 2022 will certainly be higher than in 2021. This suggests that China will become more influential in this field in the future.

The papers in this field were published in 789 journals. The journal Nutrients accounted for the largest number of publications (73), followed by other journals such as Scientific Reports (Np: 38), Frontiers in Microbiology (Np: 34), and Food & Function (Np: 26). Nutrients publishes articles on a wide range of topics, including diet-related disorders, metabolic syndrome, public health, and so on. The GM plays an important role in nutrient supply and balance (Valdes et al., 2018) but also participates in the pathological process of different diseases (Martinez et al., 2009). Therefore, studies on the GM and CVD fit well with the scope of Nutrients. Recently, more mechanisms of how the GM leads to disease have been discovered, and more than 10 papers related to the GM and CVD have been published in Nutrients in last 2 years (Liu et al., 2022; Burakova et al., 2022). It can be expected that, in the future, more papers on interesting topics in this field will published in this journal.

All keywords, clusters, and the top 20 keywords with the strongest citation bursts are shown in Figures 6 , 7 , Table 7 , and Supplementary Table 1 . Keywords represent the core content of a study. The evolution of keywords reflects the research direction of studies in the field. A cluster contains related keywords on a specific theme. In this field, all keywords were divided into 10 main clusters, with each cluster indicating a research direction. Cluster 8 (obesity) includes all studies related to obesity and GM. Obesity is one of the leading risk factors for CVD. Cluster 6 (short-chain fatty acids) comprises studies on the relationship between the GM and short-chain fatty acids. Short-chain fatty acids mediate the progress of CVD (Nogal et al., 2021) and have been implicated in the pathophysiology of atherosclerosis (Ohira et al., 2017). Apart from classifying keywords by cluster, the evolutionary path in different clusters revealed additional details in each cluster, reflecting the evolution of keywords over time. The keyword most representative of cluster 0 was initially, i.e., in 2010, “high-fat diet” but became “metabolic syndrome” in 2015 and “fatty liver disease” and “epithelial cell” in recent times. In cluster 1, the main keyword evolved from “risk” in around 2012 to “marker” in 2018, and to “prevention”, and “modulation” in recent times. “Atherosclerosis” was the most common keyword in cluster 3 in 2010, and has evolved to “metformin nutrients” in recent years. “Gut microbiota dysbiosis” was the earliest keyword and “metabolic disease” and “epidemiology” are the latest keywords in cluster 4. The earliest keyword in cluster 7 was “nitric oxide” in 2005, while recent keywords in this cluster are “pulse wave velocity” and “ammonia”. “Bacteria” was initially, in 1995, the most common keyword in cluster 8, but “inflammation” is now the most popular keyword in this cluster. “Childhood obesity” is the latest keyword in this cluster. In cluster 9, “carnitine” was the most common keyword in 2016, but has been overtaken by “cardiometabolic disease”. The emerging keywords in a specific cluster indicate the research trend or the potential research hotspot in that field.

Keywords with strong citation bursts indicate the emerging research direction. Monooxygenase-3 (cluster 9) participates in cholesterol metabolism (Schugar and Brown, 2015). It has now been confirmed to be associated with dioxin-induced reorganization of the gut microbiome and host insulin sensitivity (Massey et al., 2022). Short-chain fatty acids (cluster 6) were shown in early 2006 to improve colonic and systemic health (Wong et al., 2006), but, with the development of GM studies, the function of short-chain fatty acids has been further elucidated (Chambers et al., 2018; Bartolomaeus et al., 2019), and it is likely that short-chain fatty acids will continue to be a hot topic in the future. The cause of fatty liver disease (cluster 0), especially non-alcoholic fatty liver disease, is the subject of debate (Chiriac et al., 2021), but, interestingly, it is now thought that the GM may be involved (Drozdz et al., 2021). A Mediterranean diet (cluster 9) has been confirmed to be beneficial for CVD and some chronic diseases. However, the detailed mechanisms should be explored in randomized controlled trials (Merra et al., 2020). Intestinal barrier (cluster 2) dysfunction is associated with CVD (Li et al., 2020), and, thus, regulation of intestinal barrier function has been suggested as a promising novel therapeutic target for treating CVD (Lewis and Taylor, 2020). As the role of the GM in CVD is complicated, targeting the GM may be a double-edged sword. Despite leading to CVD, the GM is also a target for preventing CVD (Yamashita et al., 2015; Hsu et al., 2021), which is why “prevention” (cluster 1) is an emerging keyword. Although some of the emerging keywords are not immediately associated with GM and CVD, they indicate the current research direction in this field. Generally, these keywords show potential hotspots.

Research on the role of the GM in CVD has become a hotspot area in recent years. Publications on the GM in CVD have increased rapidly in the last 10 years. China is the leading country in the field, with the highest number of publications on the GM in CVD, with the USA coming a close second. However, the USA is the country that is most influential in this field. Close cooperation between different authors and countries promotes progress in this field. The journal Nutrients, among a total of 789 journals, has the highest number of publications in this field, and studies on “monooxygenase-3”, “short-chain fatty acid”, “fatty liver disease”, “metabolic disease”, “Mediterranean diet”, “intestinal barrier”, and “prevention” are likely to be published in this field. The findings of this study provided valuable insights into future studies on GM in CVD.

The original contributions presented in the study are included in the article/ Supplementary Material . Further inquiries can be directed to the corresponding authors.

PL, Y-lL, and MS designed the study. MS, W-wC, and SqX collected and chose the data. PL, MS, SqX, W-wC, F-qL, Y-xO, and Y-mZ analyzed the data and drew the figures; PL, SqX, and MS drafted the manuscript. PL and Y-lL revised the final version of the manuscript. The authors read and approved the final manuscript.