Personalized Vitamin D Supplementation for Reducing or Preventing Fatigue and Enhancing Quality of Life of Patients with Colorectal Tumor: Randomized Intervention Trial (VICTORIA)

Lab values

• Sufficient vitamin D status (25(OH)D ≥ 60 nmol/L) • Severe renal impairment (eGFR < 30 ml/min/1,73 m²) • Hypercalcemia • Hypercalciuria • High-dose vitamin D3 therapy (≥ 2,000 IU daily or similar dosage which corresponds to ≥ 2,000 IU daily) • Therapy with vitamin D analogs • Topical therapy with vitamin D3 or vitamin D analogs • Hypersensitivity towards ingredients in Dekristol® 20 000/1000 I.E.: peanuts, soy, gelatin, lactose, maize starch or sucrose or ingredients in the placebo capsules (mannitol, silicon dioxide) • Nephrolithiasis with symptoms in the last year • Pseudohypoparathyreodism • Sarcoidosis • Therapy with cardiac glycosides • Therapy with high-dose calcium-supplements (> 1000 mg calcium daily) • Participation in another intervention trial • Pregnancy, planned pregnancy in next 12 weeks, or lactation • No use of adequate contraceptive measures in women of childbearing potential

• Age ≥ 18 years • CRC patients, both men and women • CRC therapy in last 12 months (surgical removal of tumor, radiation and/or chemotherapy (adjuvant or neoadjuvant)) • At least 3 weeks in-patient rehabilitation in a cooperating clinic is planned • Sufficient knowledge of the German language and mental capabilities to be able to give written informed consent and comply with the study requirements