Higher Coffee and Caffeine Consumption Associated with Lower Ulcerative Colitis Risk

Background & Rationale

The aetiology of ulcerative colitis remains incompletely understood, though dietary and environmental factors are believed to contribute to disease development alongside genetic susceptibility. Epidemiological evidence regarding coffee consumption and ulcerative colitis risk has been inconsistent, with prior studies yielding conflicting results. Most existing research has been conducted in Western populations, and data from Asian populations remain limited. Given differences in coffee consumption patterns, dietary habits, and genetic backgrounds between populations, the relationship between coffee intake and ulcerative colitis risk in Japan warrants specific investigation. The authors undertook this study to examine associations between coffee and caffeine intake and ulcerative colitis risk in a Japanese population using a multicentre case-control design.

Study Design

This multicentre case-control study recruited participants from 37 hospitals across Japan between January 2016 and December 2019. Cases were patients with newly diagnosed ulcerative colitis. Controls were inpatients or outpatients without inflammatory bowel disease, recruited from the same hospitals and matched by age, sex, and residential area. All participants completed a self-administered questionnaire assessing dietary intake, including coffee consumption, alongside demographic and lifestyle factors. Dietary intake was evaluated using a validated food frequency questionnaire. Coffee and caffeine intake were categorised into quartiles based on control group distributions. Conditional logistic regression analysis was employed to calculate odds ratios, adjusting for potential confounders including body mass index, smoking status, alcohol consumption, physical activity, and total energy intake.

Patient Population

The study enrolled 505 cases of newly diagnosed ulcerative colitis and 1,331 control subjects. Cases and controls were frequency matched by sex, age group, and residential area. The mean age was similar between groups. Participants completed detailed questionnaires regarding coffee consumption patterns, including frequency and volume of intake. Information on caffeinated and decaffeinated coffee consumption was collected separately. Baseline characteristics including smoking history, alcohol intake, body mass index, and physical activity levels were recorded. The study excluded individuals with inflammatory bowel disease from the control group. All participants provided informed consent, and the study received ethical approval from participating institutions.

Key Findings

Coffee consumption demonstrated an inverse association with ulcerative colitis risk. Comparing the highest quartile of coffee intake to the lowest, the adjusted odds ratio was 0.56, indicating a 44 per cent reduction in risk among those consuming the most coffee. A dose-response relationship was observed, with progressively lower odds ratios across increasing quartiles of consumption. Caffeine intake similarly showed an inverse association with ulcerative colitis risk. The adjusted odds ratio for the highest versus lowest quartile of caffeine intake was 0.58, representing a 42 per cent risk reduction. This association remained significant after adjustment for multiple confounding variables. When stratified by smoking status, the protective association of coffee consumption appeared stronger among never-smokers compared to ever-smokers, though significant inverse associations were observed in both groups. Tea consumption did not demonstrate a significant association with ulcerative colitis risk. The protective associations observed for coffee and caffeine remained consistent across sensitivity analyses.

Discussion

These findings add to the body of evidence suggesting potential protective effects of coffee and caffeine against ulcerative colitis development. The biological plausibility of this association rests on several mechanisms. Caffeine and other coffee constituents possess anti-inflammatory properties and may modulate immune function. Coffee polyphenols have demonstrated antioxidant effects in experimental studies. Additionally, coffee consumption may influence gut microbiota composition, potentially affecting intestinal inflammation. The stronger protective effect observed among never-smokers warrants consideration, as smoking has complex and paradoxical effects in ulcerative colitis, with former smoking associated with increased disease risk. The lack of association with tea consumption suggests the effect may be specific to coffee compounds beyond caffeine alone, or related to caffeine dose, as coffee typically delivers higher caffeine concentrations per serving. The case-control design limits causal inference, and recall bias remains a consideration despite use of validated dietary assessment tools. Residual confounding from unmeasured factors cannot be excluded entirely.

Authors’ Conclusions

The authors conclude that higher coffee and caffeine intake are associated with reduced risk of ulcerative colitis in this Japanese population. They state that these findings suggest coffee consumption may have a preventive role against ulcerative colitis development. The authors note that the mechanisms underlying this association require further elucidation through mechanistic studies. They emphasise that prospective cohort studies are needed to confirm these findings and establish temporality of the association. The authors acknowledge limitations inherent to the case-control design, including potential recall bias and residual confounding. They suggest that if confirmed in prospective studies, dietary guidance regarding coffee consumption could potentially be considered as part of primary prevention strategies for ulcerative colitis in susceptible populations.

Reference

Tanaka K, Okubo H, Miyake Y, Nagata C, Furukawa S, Andoh A, Yokoyama T, Yoshimura N, Mori K, Ninomiya T, Yamamoto Y, Takeshita E, Ikeda Y, Saito M, Ohashi K, Imaeda H, Kakimoto K, Higuchi K, Nunoi H, Mizukami Y, Suzuki S, Hiraoka S, Okada H, Kawasaki K, Higashiyama M, Hokari R, Miura H, Miyake T, Kumagi T, Kato H, Hato N, Sayama K, Hiasa Y; Japan Ulcerative Colitis Study Group. Coffee and caffeine intake reduces risk of ulcerative colitis: a case-control study in Japan. J Gastroenterol Hepatol. 2024. doi: 10.1111/jgh.16439.