Regular exercise protects women against the development of Crohn’s disease, reveals research published in the BMJ.
However, analysis of the Nurses’ Health Study and Nurses’ Health Study II data for 194,711 women did not find that physical activity reduced the risk for the related inflammatory bowel disease, ulcerative colitis (UC).
“Taken together with previous observations that physical activity may induce autophagy and modulate innate immunity, our findings suggest that such pathways may play a stronger role in the cause of Crohn’s disease compared with ulcerative colitis,” suggest Andrew Chan (Massachusetts General Hospital and Harvard Medical School, Boston, USA) and co-authors.
Over 3,421,972 person–years of follow-up, 284 women were diagnosed with Crohn’s disease and 363 women were diagnosed with UC.
Compared with women in the lowest quintile for physical activity (median metabolic equivalent task [MET] h/week=1.0), those in the highest quintile (median MET h/week=45.2) had a significantly reduced risk for Crohn’s disease, with a hazard ratio (HR) of 0.64, after adjusting for a raft of confounders including age, smoking, hormone use, and body mass index.
And using prespecified activity levels, the team found that the likelihood for Crohn’s disease diagnosis reduced significantly with increasing activity levels, so that women in the highest category (≥27 MET h/week) had an adjusted HR of 0.56 compared with those in the lowest category (<3 MET h/week).
This translated to about a 6% reduction in the risk for Crohn’s disease per 10 MET h/week, a level of exercise achieved by 2.5 hours of brisk walking, Chan et al explain.
“Whether these associations with disease incidence may imply a benefit of physical activity on disease activity in patients with existing Crohn’s disease is unclear and merits further study,” the researchers note.
They write that further research into the impact of physical activity on the natural history of Crohn’s disease, while considering the role of autophagy and immune pathways, will help determine the etiology of the condition.
“Ultimately, this may lead to lifestyle interventions among subgroups with known genetic risk factors for Crohn’s disease to modify the risk of disease or among patients with established disease to limit its progression,” they write.
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