Plant-Based Diet Quality and Risk of Crohn’s Disease and Ulcerative Colitis in US Women

Abstract

Abstract Objectives Several plant-based foods have been associated with a lower risk of Crohn's disease (CD) and ulcerative colitis (UC), but not all plant-based foods are healthy. We aimed to examine the association of various plant-based diets with the risk of CD and UC. Methods We followed 169 945 women in the Nurses’ Health Study and Nurses’ Health Study II for up to 32 years. Plant-based diets were assessed by three indices derived from the food frequency questionnaires: an overall plant-based diet index (PDI), a healthful plant-based diet index (hPDI), and an unhealthful plant-based diet index (uPDI). Self-reported CD and UC were confirmed through medical record review. Results We documented 320 incident CD cases and 404 incident UC cases during 4 317 561 person-years. A higher hPDI was associated with a lower risk of UC (hazard ratio [HR] comparing extreme quintiles: 0.67; 95% confidence interval [CI]: 0.47–0.94; P-trend = 0.02). In contrast, the uPDI was associated with an increased risk of CD (HR: 1.67; 95% CI: 1.11–2.51; P-trend = 0.002) and UC (HR: 1.65; 95% CI: 1.15–2.35; P-trend = 0.03). Replacing refined grains, sugar-sweetened beverages, and sweets/desserts with an equal serving of fruits or vegetables was associated with lower risk of CD and UC. Conclusions A healthful plant-based diet rich in fruits and vegetables was associated with a lower UC risk, whereas a plant-based diet emphasizing less healthy plant foods such as refined grains, sugar-sweetened beverages, and sweets/desserts was associated with a higher CD and UC risk. Funding Sources National Institutes of Health.