Healthy lifestyle may mitigate genetic risk for inflammatory bowel disease

In a cohort study, U.K. residents with high genetic risk for inflammatory bowel disease who met four or five lifestyle measures developed Crohn's disease or ulcerative colitis at higher-than-average rates, but at about half the rate of those with both genetic risk and an unhealthy lifestyle.

Patients with genetic risk for inflammatory bowel disease (IBD) had significantly lower risk of developing Crohn's disease (CD) or ulcerative colitis (UC) if they followed a healthy lifestyle, a recent study found.

The cohort study used data from the UK Biobank on about 500,000 people of European ancestry recruited across the United Kingdom between 2006 and 2010. Researchers estimated genetic susceptibility to CD and UC with polygenic risk scores and categorized participants by high, intermediate, and low risk. They based healthy lifestyle scores on five common factors (smoking, body mass index, sleep, diet, and physical activity) and categorized them as favorable (4 or 5 factors), intermediate (3 factors), or unfavorable (0 to 2 factors). Results were published by the American Journal of Gastroenterology on Jan. 6.

During 12 years of follow-up, 707 CD and 1,576 UC cases were diagnosed in the study cohort. A high genetic risk score was associated with a significantly increased risk of either condition, with hazard ratios (HRs) of 2.24 (95% CI, 1.75 to 2.86) and 2.15 (95% CI, 1.82 to 2.53), respectively. However, patients with high genetic risk and a favorable lifestyle had significantly lower elevation in risk compared to those with high genetic risk and an unfavorable lifestyle (HRs for CD, 2.33 [95% CI, 1.58 to 3.44] vs. 4.40 [95% CI, 2.91 to 6.66]; for UC, 2.05 [95% CI, 1.58 to 2.66 for UC] vs. 4.44 [95% CI, 3.34 to 5.91]). Overall, HRs associated with an unfavorable lifestyle were 1.94 (95% CI, 1.61 to 2.33) for CD and 1.98 (95% CI, 1.73 to 2.27) for UC.

“To our knowledge, no previous studies have examined the association of a combination of healthy lifestyle and multiple genetic factors with risk of incident CD and UC,” the authors said. They noted that the results “verified the associations of smoking, physical inactivity, unhealthy diet, and abnormal sleep duration” with CD and UC but did not show an association between the diseases and alcohol consumption.

“One of the interesting findings was that participants at lower genetic risk and poor lifestyle still had an elevated risk of IBD,” said the authors, who added that although the finding was imprecise, it “has important clinical implications by indicating that promoting a healthy lifestyle is an effective strategy to lower incidence of these diseases, even among those with high-risk genetic background.” They noted that limitations of the study include the possibility of residual confounding and lack of generalizability to populations of different ethnicities or younger ages.