Introduction There are plausible biological mechanisms for how diet may be involved in the aetiology of Crohn's disease, with numerous case-control studies reporting positive associations with an increased sugar intake. However, these findings may be subject to recall biases for sugar intake leading to spurious results. The aim of this investigation was to eliminate this error by conducting the first multicentre European prospective cohort study of the dietary intake of total sugar and the risk of developing Crohn's disease.

Methods A total of 333 682 initially well men and women aged 20–80 years were recruited into the EPIC Study (European Prospective Investigation into Cancer). The participants were resident in The UK, Sweden, Denmark, Germany, Italy and France. At recruitment they completed food frequency questionnaires on diet from which their sugar intake was determined. Each case was matched with four controls and the odds ratios (ORs) calculated using conditional logistic regression, adjusted for total energy intake and cigarette smoking.

Results In the cohort, a total of 93 initially well participants developed Crohn's disease (71% women) at a median age of 56.7 years (range 27.0–78.7 years). The terminal ileum was affected in 44% of patients. The adjusted OR for the highest vs the lowest quartile of intake of total sugar was 1.01 (95% CI 0.41 to 2.47, p=0.98) with a trend across quartiles of 0.94 (95% CI 0.71 to 1.23, p=0.62). There were no associations with either the dietary intakes of total carbohydrates (OR for trend=0.87, 95% CI 0.62 to 1.21) or starch (OR for trend=1.16, 95% CI 0.78 to 1.72).

Conclusion This prospective cohort study found no association with the intake of total dietary sugar and the risk of developing Crohn's disease. Therefore, reports of a positive association from case-control studies is probably indicative of recall bias due to an increased sugar consumption by patients with established disease and therefore sugar does not have a role in the aetiology of Crohn's disease.