Inadequate sunlight exposure in patients with inflammatory bowel disease

Inadequate sun exposure impairs vitamin D activity and favors low bone density, especially in patients at increased risk for osteoporosis, such as those affected by inflammatory bowel disease (IBD). In this study, sun exposure was investigated in a large series of patients with IBD in a Mediterranean country, Italy, where this risk is considered less likely to occur than in higher latitudes.

This is a case-control study of 292 patients with IBD [132 with Crohn's disease (CD) and 160 with ulcerative colitis (UC)], 80 diseased and 540 healthy controls, conducted via a validated questionnaire to quantify sunlight exposure. Data were also compared with controls matched by age and gender.

In total 78 of the 292 patients with IBD had low, 169 had moderate and 45 had high exposure to sunlight, significantly differing from controls (P < 0.001). The 132 patients with CD were more likely to have abnormal levels of sunlight exposure (49 low, 72 moderate and 11 high) than those with UC (29 low, 97 moderate and 34 high) (P < 0.001). The controls were significantly more exposed to sunlight than both men and women with IBD (P < 0.001 and 0.004, respectively).

IBD patients are significantly less exposed to sunlight than matched controls in Italy, often to an extent that may impair vitamin D activation. Increasing responsible sunlight exposure, thus promoting adequate vitamin D concentrations, may prove beneficial in IBD, in geographical areas in which this risk factor is not generally taken into consideration.