Dietary Nut and Legume Intake and Risk of Crohn's Disease and Ulcerative Colitis

Background: We investigated the relationship between nut and legume intake and risk of Crohn's disease (CD) and ulcerative colitis (UC). Methods: We conducted a prospective cohort study of 223 283 adults from the Nurses' Health Study (NHS), NHSII, and Health Professionals Follow-Up Study (1986-2017), excluding those with inflammatory bowel disease (IBD) at baseline. Food frequency questionnaires were used to calculate nut and legume intake. Inflammatory bowel disease was self-reported on questionnaires and confirmed via blinded record review. Using Cox proportional hazards models, we calculated adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) for CD and UC according to categories of nut and legume intake. Results: In over 5 460 315 person-years of follow-up (CD = 371, UC = 481), neither nut nor legume intake was associated with CD or UC risk. Compared to those who never consumed nuts, those who consumed nuts >= 2 times/week had an aHR = 0.96 (95% CI, 0.63-1.47; P-trend = 0.57) for CD and 1.30 (95% CI, 0.92-1.84; P-trend = 0.36) for UC. Compared to those who consumed legumes 0-3 times/month, those who consumed legumes >= 4 times/week had an aHR of 1.26 (95% CI, 0.78-2.04; P-trend = 0.59) for CD and 0.72 (95% CI, 0.44-1.18; P-trend = 0.20) for UC. Baseline BMI modified the relationship between nut intake and CD risk (P-int = 0.03). In those with BMI >= 25, the aHR for CD was 0.14 (95% CI, 0.03-0.56; P = .006) per additional serving/day of nuts compared with 0.88 (95% CI, 0.45-1.74; P = .72) for those with BMI <25. Conclusions: Nut and legume intake were not associated with CD or UC risk. However, higher nut intake decreased CD risk in overweight or obese individuals. Thus, personalized-risk stratification, rather than generalized dietary recommendations, may be important for IBD prevention strategies. Lay Summary Here, we show that overall nut and legume intake was not associated with risk for development of IBD; however, higher nut intake decreased Crohn's disease risk in those with elevated body mass index.