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; Ptrend = 0.57) for CD and 1.30 (95% CI, 0.92-1.84; Ptrend = 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; Ptrend = 0.59) for CD and 0.72 (95% CI, 0.44-1.18; Ptrend = 0.20) for UC. Baseline BMI modified the relationship between nut intake and CD risk (Pint = 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.