Modifiable lifestyle factors in early life and inflammatory bowel disease risk in two birth cohorts

Early life may be a critical period for the development of inflammatory bowel disease (IBD) susceptibility. The aim was to examine the association between early-life adherence to a healthy lifestyle and later IBD risk.

In two Scandinavian birth cohorts (1997-2009), we developed the a priori Modifiable Health-related Lifestyle Score (MHLS) and an empirically weighted Optimal Risk Score (ORS) by ages 1 and 3 years, incorporating data on smoking exposure, delivery mode, breastfeeding, diet quality, antibiotic use, physical activity, and body mass index. Linked national registers identified diagnoses of any IBD, Crohn's disease (CD), and ulcerative colitis (UC) through 2023-2024. Cox regression and random-effects models, adjusted for parental IBD and sociodemographic characteristics, were used to estimate pooled hazard ratios (aHRs) across MHLS and ORS tertiles.

By a mean age of 20 years at the end of follow-up, 732 of 117 487 participants were diagnosed with IBD. Children with high vs low MHLS by age 1 year had a reduced risk of later IBD (aHR = 0.77 [95% CI = 0.61-0.98]), particularly CD (aHR = 0.57 [0.38-0.86]). ORS analyses yielded estimates nearly identical to MHLS by age 1 year and showed that high vs low adherence to a healthy lifestyle by age 3 was associated with a reduced risk of IBD (aHR = 0.77 [95% CI = 0.63-0.95]) and CD (aHR = 0.68 [95% CI = 0.49-0.94]), but not of UC. Associations were similar for childhood-onset IBD.

A healthy lifestyle in early childhood was associated with a reduced risk of IBD, particularly CD, suggesting that early lifestyle modifications may help prevent the disease.