In a recent study published in the journal Nutrients, researchers investigated the association between coffee consumption and irritable bowel syndrome (IBS) risk.

Study: Examining the Association between Coffee Intake and the Risk of Developing Irritable Bowel Syndrome: A Systematic Review and Meta-Analysis. Image Credit: Kingmaya Studio / Shutterstock.com

IBS and the benefits of coffee

IBS is a common disorder that affects the gastrointestinal tract and is characterized by abdominal discomfort, diarrhea, constipation, and bloating. Current estimates indicate that IBS affects 5-10% of the world’s population. IBS is associated with significant losses, both in the quality of life of affected individuals and socioeconomically.

The consumption or elimination of certain food items has been shown to worsen or improve IBS symptoms in many individuals. For example, the Mediterranean-style diet, rich in fresh fruits and vegetables, whole grains, seeds, and nuts, has consistently been shown to alleviate symptoms of IBS and improve overall health outcomes.

Coffee is the second most consumed beverage in the world after water and the most popular daily drink. Umbrella reviews on coffee consumption have revealed that three to four cups daily provide the overall best health outcomes. Despite numerous studies investigating the association between coffee drinking and IBS, the results remain inconclusive and often confounding.

Coffee contains several bioactive molecules that have been hypothesized to interact with the gut microbiome, alter intestinal permeability, promote bile acid metabolism, and even improve the functioning of the central nervous system (CNS).

About the study

The current study aims to evaluate the association between coffee intake and the risk of subsequent IBS development. The researchers employed a systematic review and meta-analysis approach in compliance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

Data were collected from studies obtained from the EMBASE, PubMed, and the Cochrane Library databases from inception until March 31, 2023. Inclusion criteria comprised publications that reported associations between coffee intake and IBS, were randomized controlled trials (RCTs), case-control investigations, and cross-sectional studies, and published in English.

Publication year, geographical study location, study population demographics, and clinical outcomes were extracted from all studies. All extracted data were processed through double coding to verify and ensure precision.

Outcomes were measured using reported standard deviation (SD) values for continuous variables and percentages or frequencies for categorical variables. Publication bias was evaluated using the Newcastle-Ottawa Scale (NOS).

Statistical analyses included calculating the odds ratios (ODs), the results of which were pooled. Egger’s regression was used to report publication bias and its interpretation of results where applicable.

Study findings

A total of 187 studies were identified, eight of which met the inclusion criteria for the meta-analysis. The studies comprised a total sample cohort of 432,022 individuals. Study bias assessment revealed a moderate to high risk of bias, which was highest in selected cross-sectional studies.

Selected studies comprised cohorts predominantly from Asia (n = 6), with one each from Africa and the United Kingdom, respectively. IBS diagnoses within included studies followed the ROME III criteria for IBS symptoms, with one exception that used ROME II. Levels of coffee consumption varied between studies, with some reporting a binary study design of drinkers versus abstainers, while others had more detailed cohort allocation.

A fixed effects model revealed that across the included studies, coffee consumers were less likely to develop IBS as compared to their abstainer counterparts, with an OR of 0.84. Stability analyses verified that these findings were accurate across the 432,022-strong sample size despite differences in study-specific methodologies.

Conclusions

The present study used a fixed effects meta-analysis model to investigate the association between coffee intake and subsequent IBS risk. Analyses encompassed eight studies spread across three continents, with a pooled sample size of over 432,000.

The study findings reveal that coffee consumption of any quantity or frequency was associated with a reduced risk of subsequently developing IBS.

Future research in this area should (1) prioritize high-quality prospective cohort studies with well-documented coffee consumption (and exposure) and track the development of incident IBS in previously healthy individuals over time, and (2) investigate biological mechanisms.”

Written by

Hugo Francisco de Souza

Hugo Francisco de Souza is a scientific writer based in Bangalore, Karnataka, India. His academic passions lie in biogeography, evolutionary biology, and herpetology. He is currently pursuing his Ph.D. from the Centre for Ecological Sciences, Indian Institute of Science, where he studies the origins, dispersal, and speciation of wetland-associated snakes. Hugo has received, amongst others, the DST-INSPIRE fellowship for his doctoral research and the Gold Medal from Pondicherry University for academic excellence during his Masters. His research has been published in high-impact peer-reviewed journals, including PLOS Neglected Tropical Diseases and Systematic Biology. When not working or writing, Hugo can be found consuming copious amounts of anime and manga, composing and making music with his bass guitar, shredding trails on his MTB, playing video games (he prefers the term ‘gaming’), or tinkering with all things tech.