Abstract
INTRODUCTION: Dairy consumption has been linked to the development of autoimmune diseases. We aimed to examine the association between dairy intake and risk of incident inflammatory bowel disease.
METHODS: We conducted a prospective cohort study of 197,763 participants without a baseline diagnosis of inflammatory bowel disease in 1986 in Nurses' Health Study, 1991 in Nurses' Health Study II (NHSII), and 1986 in Health Professionals Follow-up Study. Data on dairy intake were collected every 2-4 years using a validated semi-quantitative food frequency questionnaire and modeled according to quintiles for total intake and quartiles for components of dairy. We used Cox proportional hazard modeling to estimate adjusted hazard ratios and 95% CIs.
RESULTS: Through the end of follow-up in 2016 in Nurses' Health Study and Health Professionals Follow-up Study, and 2017 in Nurses' Health Study II, we documented 347 Crohn's disease cases and 428 cases of ulcerative colitis (UC). In our primary analysis, we observed an inverse association between baseline dairy intake (P trend = 0.04) and risk of UC (adjusted hazard ratio of 0.72 [95% CI 0.52-1.00 comparing extremes of quintiles]). Among dairy components, baseline yogurt consumption (hazard ratio = 0.70; 95%CI 0.5-0.99; P trend = 0.05) was most strongly associated with decreased risk of UC. There was no consistent association between dairy intake and risk of Crohn's disease.
DISCUSSION: In 3 large prospective cohort studies, we observed a suggestive inverse association between baseline dairy intake, particularly from yogurt, and risk of UC. Future studies are needed to confirm these results.