Higher Dietary Glycemic Index, but not Glycemic Load, is Associated with Increased Risk of Ulcerative Colitis: A Prospective Cohort Study

We included 121,148 UK Biobank participants without IBD at baseline, and collected dietary information from a validated web-based 24-hour dietary recall questionnaire. Overall dietary glycemic index and glycemic load was estimated. Cox proportional hazard models were used to calculate multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs). Substitution analyses were conducted to test associations after replacing medium or high glycemic index foods with low glycemic index foods. During a median follow-up of 10.6 years, 133 incident CD and 335 incident UC cases were identified. Dietary glycemic index was associated with UC but not CD. The HR of UC was 1.13 (95% CI 1.01-1.27) per 1 standard deviation increment and 1.46 (95%CI 1.07-1.99) for the highest versus lowest quartile of glycemic index. Replacing medium or medium and high glycemic index foods with low glycemic index foods was associated with a lower risk of UC. No significant associations were found between dietary glycemic load with risk of CD and UC. A higher dietary glycemic index, but not glycemic load, is associated with an increased risk of UC, underscoring the importance of considering glycemic index in dietary recommendations for UC prevention.