P652 Underweight patients with Crohn’s disease and without vitamin D supplementation are at high risk of vitamin D deficiency

Background Vitamin D deficiency is frequently present in inflammatory bowel disease (IBD) with a higher incidence in Crohn’s disease (CD) than in ulcerative colitis (UC). Given the involvement of the alimentary tract, many factors can contribute to vitamin D deficiency. The aim of the study was to investigate the association of vitamin D deficiency according to body mass index (BMI) in adult patients with IBD. Methods A cross-sectional study was conducted on a cohort of 152 IBD patients, 68.1% (n = 104) CD and 31.9% (n = 48) UC. The mean age of the total study population was 37.3±11.8 years and 57.3% (n = 87) were male. All patients were adult, Caucasian and without vitamin D supplementation. Patients were recruited during one year period. Results Out of all IBD patients, 60.5% (n = 92) had vitamin D deficiency, 32.2%, (n = 49) insufficiency and 7.2% (n = 11) sufficiency. According to BMI categories there were 12.5% (n = 19) obese patients, 27.6% (n = 42) overweight, 51.3% (n = 78) with normal body weight, and 8.6% (n = 13) underweight. There was a significant difference in vitamin D levels according to different BMI categories in terms of underweight patients having the lowest vitamin D levels; underweight 29.84±11.94 mmol/l, normal 46 ± 20.7 mmol/l, overweight 48±20.1 mmol/l, obese 51±15.3 mmol/l. In addition, there was a significant correlation of vitamin D levels and BMI values (Rho = 0.212, 95% CI 0.069–0.345, p = 0.004), which was more clearly observed in the lower range of BMI values (Figure 1). Male underweight patients had lower levels of vitamin D compared with female patients (26.6 ± 9 vs. 34.7 ± 5.6, p < 0.05). Both patients with CD and UC had significant positive correlation of vitamin D levels and BMI values (UC Rho=0.40, 95% CI 0.16–0.59, p = 0.001, UC Rho = 0.27, 95% CI 0.01–0.05, p = 0.044). However, when comparing vitamin D levels according to phenotype, a significant difference in vitamin D levels was observed in underweight CD (28.4 ± 11.1) comparing to underweight UC patients (40.6 ± 10.6), p < 0.05. In logistic regression analysis, CD phenotype was risk factor for vitamin D deficiency (OR 2.18 95% CI 1.01–4.72, β = 1.22, p = 0.04). Conclusion Our results on untreated IBD patients show a high proportion of vitamin D deficiency both in CD and UC, and significant correlation of vitamin D levels and BMI values, especially in the lower range of BMI values. Moreover, underweight CD patients have lower vitamin D levels comparing to UC. This suggests the need for regular vitamin D monitoring and supplementation especially in IBD patients at risk.