High Dose Interval Vitamin D Supplementation in Patients With Inflammatory Bowel Disease Receiving Biologic Therapy

This study is testing whether giving high doses of vitamin D at scheduled intervals helps maintain better vitamin D levels in children and young adults with inflammatory bowel disease (IBD — Crohn's disease or ulcerative colitis) who are already receiving biologic (IV) therapy. Many IBD patients have low vitamin D, and researchers want to know if this approach can safely correct it. **You may be eligible if...** - You are between 5 and 25 years old - You have a diagnosis of IBD (Crohn's disease, ulcerative colitis, or indeterminate colitis) - You are currently receiving infliximab or vedolizumab infusions every 4–8 weeks - Your vitamin D level (25-OHD) was below 40 ng/mL in the last 4–8 weeks **You may NOT be eligible if...** - You have kidney disease, liver disease, or a granulomatous disease (like sarcoidosis) - You have a history of high calcium levels - You cannot swallow a vitamin D pill - You are currently taking anti-seizure medications or the diuretic furosemide (Lasix) Talk to your doctor to see if this trial is right for you.