The supplementation will be performed in patients with serum vitamin D levels below 29 ng/Ml. The replacement with cholecalciferol (vitamin D3) tablets will be provided at no cost to the patients. The dosage of 1.500-2.000 IU (International Units) vitamin D/day is recommended in order to meet the need of vitamin D above 30ng/ml in adults. However, a dose at least 2 to 3 times higher is recommended for CD patients due to malabsorption, significant loss of adipose tissue and use of glucocorticoids. Thus, the dose of 50000IU/week will be administered.