Obese adults see increased risk of Crohn’s disease


Obesity in adulthood was associated with a 34% increased risk of developing Crohn’s disease, while no such link was seen with ulcerative colitis, according to a pooled analysis of large prospective studies .

Compared to adults with a normal baseline body mass index (BMI), those with a BMI of 30 or more had a higher risk of older Crohn’s disease, with a combined adjusted risk ratio (aHR) of 1. 34 (95% CI 1.05 -1.71), reported Simon Chan, MD, of the Norfolk and Norwich University Hospital NHS Trust in England, and colleagues.

In the entire study population, every 5% increase in BMI was associated with a 16% higher risk of developing Crohn’s disease (aHR 1.16, 95% CI 1.05-1, 22), reaching 22% for every 5% increase in BMI in people aged 18 to 20. elderly (aHR 1.22, 95% CI 1.05-1.40), based on the results of Clinical gastroenterology and hepatology.

Meanwhile, the researchers found no relationship between the risk of ulcerative colitis for people with a BMI of 30 or greater (aHR 0.88, 95% CI 0.72-1.08).

“Our data imply that the growing burden of obesity may be contributing to the growing incidence of Crohn’s disease around the world,” Chan said. MedPage today.

“Previous epidemiological studies have not established a consistent link between obesity and the risk of CD [Crohn’s disease] and UC [ulcerative colitis]”He continued.” This was likely due to the significant limitations of previous studies, including retrospective design, smaller sample size, and the inability to control for confusion from other important exposures related to the lifestyle and the lack of detailed obesity measures. “

In 2005, the prevalence of obesity in Western Europe and the United States was 15 to 29%, increasing from 20 to 36% in 2016. Assuming a cause and effect relationship, the authors noted, would give a risk attributable to Crohn’s disease ranging from 5% to 11%.

“Future work will consider examining the precise mechanisms by which obesity may influence the etiopathogenesis of CD,” Chan said.

“Our observation that BMI in early adulthood is associated with an increased risk of late-onset CD is supported by a study that reported that obesity in children (ages 8 to 13) is associated with CD before the age of 30, “Chan’s group noted.

“Obesity, and in particular mesenteric fat, is associated with a pro-inflammatory condition that contributes to metabolic syndrome and is associated with other ‘Western diseases’ including diabetes and coronary heart disease,” Stephen B. Hanauer , MD, of Northwestern University in Chicago. , Told MedPage today. “Increased gut permeability is another potential contributor and may have a more direct impact on the development of CD.”

Hanauer, who was not involved in this study, warned that the findings “remain associative rather than causative” and will require further consideration in other age groups, “including young adults who have the greatest predilection as well as the phenotypic attributes of “obesity associated with ‘CD.”

“Additional dietary contributions, microbiome impact, and other potential confounders require further investigation to provide clearer information on potential causes,” he said.

Previous, smaller studies examining associations between obesity and inflammatory bowel disease (IBD) have shown inconsistent results. Therefore, the group aimed to further assess the issue in the largest study to date, using a pooled analysis of five prospective cohorts included in Dietary and Environmental Factors IN-IBD (DEFINe-IBD), an international consortium of studies cohort in the United States and Europe.

A total of 601,009 participants from nine countries were included, with an average follow-up of 16 years. The participants were between 18 and 98 years old, although most were middle-aged and 71% were women. A total of 1,047 participants had ulcerative colitis and 563 had Crohn’s disease.

Measurements were taken for waist-to-hip ratios and baseline BMI, in addition to lifestyle factors. People with a low BMI (

Risk ratios were adjusted for smoking status, gender, physical activity, dietary fiber (Crohn’s) or fat (ulcerative colitis), as well as total fat, fiber, or energy intake. BMI was used as a covariate to assess secondary exposures.

Limitations of the study included the use of exposure assessment questionnaires that were given to various participants to calculate BMI over several durations (1986 to 1997), which may have changed over time. In addition, the measurements were only taken at one point. The researchers further noted the limited number of cases of Crohn’s disease in those aged 18 to under 40.

Finally, given that the participants were mostly middle-aged Westerners, Chan and his coauthors acknowledged that the findings may not extend to non-Westerners or young patients with IBD. They also noted that the life exposures and environmental factors attributed to the outcomes were also not fixed and remained subjective.

Last updated on July 08, 2021

  • Zaina Hamza is a writer for MedPage Today, covering gastroenterology and infectious diseases. She is based in Chicago.


Funding for the research grants was provided by the Crohn’s and Colitis Foundation, and other funding for the studies came from various government agencies and other organizations in the United States and Europe.

Chan disclosed Abbvie and Takeda’s travel grants. The co-authors have reported relationships with Takeda, AbbVie, Pfizer, Janssen, Ferring, the Swedish inflammatory bowel disease registry, Boehringer Ingelheim and Bayer Pharma AG.

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