Objective To examine the relationship between Mediterranean diet and risk of later-onset Crohn’s disease (CD) or ulcerative colitis (UC).
Design We conducted a prospective cohort study of 83 147 participants (age range: 45–79 years) enrolled in the Cohort of Swedish Men and Swedish Mammography Cohort. A validated food frequency questionnaire was used to calculate an adherence score to a modified Mediterranean diet (mMED) at baseline in 1997. Incident diagnoses of CD and UC were ascertained from the Swedish Patient Register. We used Cox proportional hazards modelling to calculate HRs and 95% CI.
Results Through December of 2017, we confirmed 164 incident cases of CD and 395 incident cases of UC with an average follow-up of 17 years. Higher mMED score was associated with a lower risk of CD (Ptrend=0.03) but not UC (Ptrend=0.61). Compared with participants in the lowest category of mMED score (0–2), there was a statistically significant lower risk of CD (HR=0.42, 95% CI 0.22 to 0.80) but not UC (HR=1.08, 95% CI 0.74 to 1.58). These associations were not modified by age, sex, education level, body mass index or smoking (all Pinteraction >0.30). The prevalence of poor adherence to a Mediterranean diet (mMED score=0–2) was 27% in our cohorts, conferring a population attributable risk of 12% for later-onset CD.
Conclusion In two prospective studies, greater adherence to a Mediterranean diet was associated with a significantly lower risk of later-onset CD.
- Crohn's disease
- ulcerative colitis
- inflammatory bowel disease
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Contributors HK: study concept and design, analysis and interpretation of data, drafting manuscript, critically revising manuscript. NH: data acquisition, critically revising manuscript. SC, PL, JFL, ATC, OO and ARH: study concept and design, critically revising manuscript. YC: statistical analysis. AW: study concept and design, data acquisition, analysis and interpretation of data, drafting manuscript, critically revising manuscript.
Funding This work was supported by the National Institute of Diabetes and Digestive and Kidney Diseases K24 DK098311 and a Crohn’s and Colitis Foundation Senior Research Award to ATC. Dr Chan is also the Stuart and Suzanne Steele MGH Research Scholar. We acknowledge the Swedish Infrastructure for Medical Population-based Life-course Environmental Research (SIMPLER) for provisioning of facilities and database. SIMPLER receives funding through the Swedish Research Council under grant no 2017-00644.
Competing interests HK receives consulting fees from Abbvie. HK also receives grant support from Takeda and Pfizer. ATC receives consulting fees from Janssen, Pfizer and Bayer Pharma AG. SC has received consulting fees from Abbvie, Takeda and Ferring. OO has been Principal Investigaor (PI) on projects at Karolinska Institutet partly financed by investigator-initiated grants from Janssen, Ferring, Takeda and Pfizer. None of those studies have any relation to this study. Karolinska Institutet has received fees for OO's lectures and participation on advisory boards from Janssen, Ferring, Takeda and Pfizer regarding topics not related to this study. OO was supported by grants from the Swedish Medical Society (Project grants; Fund for Research in Gastroenterology; and Ihre Foundation), Mag-tarmfonden, Karolinska Institutet Foundations, Swedish Foundation for Strategic Research and Regional Agreement on Medical Training and Clinical Research between Stockholm County Council and Karolinska Institutet. JFL coordinates a study on behalf of the Swedish IBD quality register (SWIBREG). This study has received funding from Janssen.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data may be obtained from a third party and are not publicly available. Request for additional data relevant to this study should be made to Dr Alicja Wolk at email@example.com.
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