How do dietary patterns influence inflammatory bowel disease?

By Neha MathurAug 7 2023Reviewed by Sophia Coveney

In a recent article published in Nutrients, researchers used bibliometrics, a quantitative analysis method, to analyze the past 30 years (1993–2023) of data from the Web of Science Core Collection (WoSCC) database describing the effects of dietary patterns on inflammatory bowel disease (IBD).

Background

The prevalence of IBD, including ulcerative colitis (UC) and Crohn’s disease (CD), is increasing globally, but its etiology is less understood.

Among others, dietary patterns have received the most attention as an environmental factor related to the occurrence of IBD. Several recent studies have shown that high sugar, high fat, high salt, and low fiber diets increase the risk of IBD.

Despite the well-recognized significance of diet adjustment and nutritional interventions in IBD, no bibliometric analysis has ever been undertaken in this important research field of medicine.

Bibliometrics can reveal research hotspots and trends and help present summary statistics and analyses of citation relationships, authors, keywords, and other data in the published literature.

About the study

In the present study, researchers first retrieved 1,092 relevant papers from the WoSCC database related to the effects of diet on IBD. Next, they used the R language (v 4.3.0) bibliometrix package (v 4.1.2) and CiteSpace (v 6.1.R6) to analyze plain text files, and VOSviewer (v 1.6.19) and the Online Analysis Platform for Bibliometrics (OALM) for tab-delimited files of the whole records and cited references, which fetched 1,074 documents from the 1993–2023 period for analysis.

All four bibliometric analysis tools served a unique function. For instance, the OALM platform helped with the relationship network analysis and CiteSpace with co-occurrence, cluster, and emergent analyses. Likewise, VOSviewer and the bibliometrix package helped the researchers do co-occurrence and cluster analyses and frequency, relational network, and geographic visualization analyses, respectively.

The researchers also used Journal Citation Report (JCR) 2021 edition to document the journal name, impact factor (IF), and ranking.

Results

The development of this research field had two prominent periods: a slow developmental stage between 1993 and 2006 and a significant growth stage after 2006. The growth of relevant publications in this field conformed to Price’s literature growth curve; thus, one might anticipate rapid growth in such research papers even in the future.

Subrata Ghosh and Antonio Gasbarrini had the highest academic influence in this research field, followed by Lee D., whose research is also widely recognized by other researchers. Notably, their research conformed to the generalized Lotka’s law. 

Ghosh S.'s representative work describes how the intestinal microbiome affects human mood, behavior, immunity, and IBD.

Gasbarrini A. introduced the variations in gut microbiota in individuals with varying diets, stress levels, diseases, and antibiotic usage.

In another study, Gasbarrini A. reviewed the effects of different dietary components on the intestinal microbiome. He found that plant proteins, such as polyphenols, micronutrients, etc., benefit intestinal health. The authors’ clustering analysis uncovered that the connection between IBD and dietary patterns was associated with gut microbiota and lipids.

Of 72 countries, the United States of America (USA) contributed the most, while China is rapidly gaining momentum in recent years. Harvard University ranked first in the number of research papers and node centrality to emerge as the top institute in this research field. 

All highly cited studies (n=15) covered the epidemiological status of IBD globally, dietary patterns that mitigated or aggravated the effects of IBD, and the relationship between dietary patterns and intestinal microbiota. 

Studies with most emerging and core references related to gut flora had the highest frequency, suggesting that intestinal microbes are an important focus of research when exploring the effects of dietary patterns on IBD. The journal analysis uncovered that research in this field and its sources were likely to be published in high-impact journals, most of which were JCR Q1 journals.  

Through keyword cluster analysis, the authors identified studies evaluating dietary patterns beneficial or detrimental to IBD patients, and some studies also examined IBD diseases. These studies demonstrated that in UC patients, gut microflora acted on dietary fibers to produce short-chain fatty acids (SCFAs) that interacted with G protein-coupled receptor 43, a process having beneficial effects on gut inflammatory diseases. 

The emergent analysis revealed that early studies in this research field focused on the clinical and pathological characteristics of IBD-associated diseases; during the medieval stages, the research focused on IBD risk factors and pathophysiological processes. However, gut microbiota is the current research focus, and this pattern would likely continue.

Studies have been exploring the molecular mechanism through which dietary patterns affect IBD and found that nuclear factor kappa B (NF-κB), oxidative, and endoplasmic reticulum stresses played a key role in these processes. For instance, a preclinical study showed that oxyberberine mediates inhibition of the NF-κB pathway to improve UC in rats. Likewise, the Mediterranean diet reduces inflammatory biomarkers in IBD patients and improves IBD-related diseases, e.g., non-alcoholic fatty liver disease, partially by altering the gut microbiota.

Conclusions

The study results provided a theoretical basis for follow-up studies on the effects of dietary habits on IBD. Healthy eating and living habits could help manage IBD, reduce the medical, social, and financial burden of IBD globally, and improve the life quality of IBD patients.

Further, the results showed that adherence to a Mediterranean diet could significantly benefit IBD patients. Among dietary components: fatty acids, inulin-type fructans, and carbohydrates were closely related to IBD. Future research would most likely focus on the identified hot spots, including intestinal microbiota, fatty acids, NF-κB, and oxidative and endoplasmic reticulum stresses.