November 3, 2020
Are pro-inflammatory diets linked to IBD?
Pro-inflammatory diets are associated with increased risk of Crohn’s disease but not ulcerative colitis. Conclusions about causation are tempting, but other confounding factors cannot be excluded.
Lo C, Lochhead P, Khalili H, et al. Dietary Inflammatory Potential and Risk of Crohn’s Disease and Ulcerative Colitis. Gastroenterol> 2020;159(3):873–83; https://doi.org/10.1053/j.gastro.2020.05.011
Prior research has suggested certain foods or food groups are linked with gut epithelial barrier disruptions, modified intestinal immune responses, and altered microbial composition. To shed more light on the link between inflammatory diets and risk of IBD, researchers at Harvard Medical School and several other centers analyzed data from 166,903 women and 41,931 men who participated in the prospectively conducted Nurses’ Health Study (1984-2014), the Nurses’ Health Study II (1991–2015), and the Health Professionals Follow-up Study (1986–2012).
Participants in all three studies completed dietary questionnaires at study outset and every two years and were examined for a variety of health outcomes. Subjects were 44 years of age on average and had no IBD diagnosis at baseline. They were followed-up for roughly five million person-years, cumulatively. The authors used questionnaire responses to calculate empirical dietary inflammatory pattern (EDIP) scores. EDIP is a previously validated measure that scores the inflammatory potential of an individual’s diet based on their consumption of 18 food groups linked with higher levels of plasma IL-6, C-reactive protein and TNF-alpha. During follow-up, 328 cases of medical record-confirmed Crohn’s disease (CD) and 428 cases of ulcerative colitis (UC) were identified. Patients were a median 55 years of age at IBD diagnosis.
In quartile analyses, those with the highest cumulative average EDIP scores were 51% more likely to develop CD than those with the lowest scores (Hazard Ratio [HR]: 1.51; 95% Confidence Interval [CI], 1.10–2.07; P trend = 0.01). This analysis controlled for consumption of fibre and a host of non-dietary inflammatory triggers, such as smoking. Results also showed individuals who switched from a low- to a high-EDIP diet had a two-fold higher risk of CD than those who consistently followed a low-EDIP diet (HR 2.05; 95% CI, 1.10–3.79), while those who switched from a high- to a low-EDIP diet during follow-up had a statistically similar likelihood of having a CD diagnosis as those who consistently followed a low-EDIP diet.
EDIP scores were not linked with the risk of developing UC.
Study Design: Retrospective multi-cohort analysis
Funding: National Institutes of Health, the Beker Foundation, the Chleck Family Foundation and the Crohn’s and Colitis Foundation
Level of Evidence: 1b