High School Diet and Risk of Crohn's Disease and Ulcerative Colitis

Background: Diet may play an important role in the pathogenesis of Crohn's disease (CD) and ulcerative colitis (UC); yet, there are few prospective studies of dietary factors. None have examined the association between adolescent diet and risk of inflammatory bowel diseases (CD and UC). Methods: This study included women enrolled in Nurses' Health Study II who completed a validated high school dietary questionnaire in 1998. We examined the effect of dietary patterns (prudent or Western diet) and individual components of each patterns. We documented incident cases of CD and UC through 2011 based on physician review of medical records and used Cox proportional hazards models adjusting for confounders to estimate hazard ratios and confidence intervals for CD and UC. Results: Over 763,229 person-years of follow-up, we identified 70 incident cases of CD and 103 cases of UC. Compared with women in the lowest quartile of a prudent diet score (characterized by greater intake of fruits, vegetables, and fish), women in the highest quartile had a 53% lower risk of CD (hazard ratio, 0.47; 95% confidence interval, 0.23-0.98; P trend 0.04). Specifically, greater intake of fish (P trend 0.01) and fiber (P trend 0.06) were associated with lower risk of CD. In contrast, Western diet score was not associated with risk of CD. Neither dietary patterns nor individual food or nutrient groups was associated with UC. Conclusions: Adolescent diet is associated with risk of CD, but not UC, offering insights into disease pathogenesis.