Vitamin D is essential for anyone with IBD. Get your blood tested and take up to 20,000 IUs a day until it reaches at least 50ng/ml. you can go up to up 80 or 90ng/ml with enough magnesium in your diet. You may have to take magnesium becasue conversion of D into active form requires it and if there isn't enough it won't be utilized. Green juices are good for that, as are chelated magnesium tablets (bisglycinate).