Obesity links to increased risk for Crohn’s disease
“As a major environmental factor in the development of autoimmune diseases, obesity may contribute substantially to the etiopathogenesis of inflammatory bowel disease, particularly in those with older-onset IBD, where relative to those with younger disease onset the overall contribution of the environment is significantly greater,” Simon Chan, PhD, Norfolk and Norwich University Hospital NHS Trust, and colleagues wrote. “Obesity is further associated with increased markers of bowel inflammation based on fecal calprotectin measurements and intestinal permeability, biological hallmarks of IBD. Yet despite these compelling data, epidemiologic studies have failed to identify a consistent link between obesity and the risk of CD and UC.”
To investigate the association between obesity and the risk for CD and UC, Chan and colleagues performed a pooled analysis of five prospective cohort studies with validated anthropometric measurements for BMI, waist–hip ratio and lifestyle factors ascertained from baseline questionnaires. Of 601,009 participants, researchers identified 563 incident cases of CD and 1,047 incident cases of UC over a mean follow-up of 16 years.
According to study results, a baseline BMI greater than or equal to 30 kg/m2 correlated with an increased risk for CD (pooled adjusted HR = 1.34; 95% CI, 1.05-1.71) compared with a normal BMI (18.5 kg/m2 to < 25 kg/m2). Further, every 5 kg/m2 increment in baseline BMI and in early adulthood (18-20 years) BMI correlated with a 16% increased risk for CD (aHR = 1.16; 95% CI, 1.05-1.22) and a 22% increased risk for CD (aHR = 1.22; 95% CI, 1.05-1.4), respectively. Conversely, researchers observed no association between obesity and risk for UC.
“The growing burden of obesity is likely contributing to the increasing incidence of CD worldwide. Together with previous observations that obesity modulates immune responses, intestinal permeability and alterations in the gut microbiota such pathways may play a more important role in the etiopathogenesis of CD compared with UC,” Chan and colleagues concluded. “Future work should consider examining the precise mechanisms through which obesity may influence the etiopathogenesis of CD.”