Smoking, Physical Activity, Nutrition and Lifestyle: Environmental Factors and Their Impact on IBD

Abstract

Current smoking increases the risk of developing Crohn’s disease and worsens its course, increasing the need for steroids, immunosuppressants, and re-operations. On the contrary, smoking protects against ulcerative colitis and after disease onset improves its course, decreasing the need for colectomy. Smoking cessation improves Crohn’s disease and worsens ulcerative colitis. Achieving smoking cessation in Crohn’s disease is thus an important goal of therapy, whereas patients with ulcerative colitis should not be discouraged to quit, because the beneficial effect of smoking for their disease is counterbalanced by the deleterious respiratory and cardiovascular effects of tobacco. Physical activity improves quality of life without detrimental effect on disease activity, and may contribute to increase muscle mass and to prevent osteoporosis. Regarding nutrition, a Western diet may be associated with an increased risk of IBD, and a case-control study revealed an increased consumption of linoleic acid before diagnosis of ulcerative colitis. Liquid diets may improve Crohn’s disease flares and decrease the need for steroids; however, there are no defined diets able to improve the disease course, and in Crohn’s disease, supplementation with omega-3 fatty acids did not show a significant benefit. Obesity is becoming more prevalent in IBD and may be associated with higher disease activity. In total, adhering to four simple lifestyle factors – never smoking, physical activity, prudent diet and body mass index <25 – may have a strong impact both on the prevention of major chronic diseases and on the course of IBD.

The effect of increasing physical activity and/or omega-3 supplementation on fatigue in inflammatory bowel disease

“…Evidence to date suggests that individuals with IBD should benefit from increased exercise [15,22,23,53,54], and in particular, that low-moderate intensity PA is safe [19,55]. The results from our study support these findings: no serious adverse effects related to exercise were reported.…”

“…Recent evidence suggests similarities in fatigue between different conditions [12,13], though it is unclear which elements of fatigue co-exist. Although physical activity (PA) has been suggested to be appropriate for adults and children with IBD [14,15], patients may raise concerns regarding exerciserelated exacerbation of their symptoms [16].…”

The Search for Causative Environmental Factors in Inflammatory Bowel Disease

“…Cigarette smoking definitely is a risk factor for flares of CD and for perianal complications [78][79][80][81] . Smoking has a clear negative effect on the disease course [78][79][80][81] . On the other hand, smoking is protective and prevents flares in UC [78,82] .…”

“…Smoking has a clear negative effect on the disease course [78][79][80][81] . On the other hand, smoking is protective and prevents flares in UC [78,82] . The mechanisms behind that are unclear.…”

Interaction between Susceptibility and Environment: Examples from the Digestive Tract

“…Increased lifetime risk to develop CD was reported in current smokers when compared with non-smokers by Calkins [53] (OR 2.0, 95% CI 1.65–2.47) as well as Mahid et al [54] (OR 1.76, 95% CI 1.40–2.22). This risk to develop CD decreases after 4 years of having quit smoking [49,55,56]. …”