I am deficient at 11 ng/ml Actually 11 ng/ml is pretty low. Optimum range is 40-60 ng/ml. Over 100 ng/ml is flirting with overdose. Optimum range of 40-60 ng/ml is the equivalent of around 100-150 nmol/L.
The general rule of thumb is adding 1,000 iu will increase your level by 10 points. So if your level is 11 ng/ml, then by supplementing with 3,000 iu of vitamin D3 will increase your level to around 41 ng/ml. BTW it is better to supplement with vitamin D3 which is the natural form rather than vitamin D2 which is less absorbed.
Many IBDers cannot absorb vitamins very well so some of us need to take more. The only way to find out is to supplement with vitamin D for a few months and see what your blood levels are. I need 5,000 IU/day to keep my D levels in the 50's ng/ml. Some here take much more. On the other hand over 100 ng/ml is flirting with overdose so there is no substitute for regularly checking your levels.
Most people are deficient in vitamin D but even more so if you have IBD. If you google “vitamin D Crohn's”, “vitamin D ulcerative colitis”, “vitamin D cancer”, or vitamin D anything you will see that it is important for maintaining health against a host of diseases.
m.medicalxpress.com/news/2015-06-vitamin-d-crohn-disease.htmlIn a double-blind randomised placebo-controlled study, the authors assigned 27 CD patients in remission to 2000 IU/day vitamin D supplementation or placebo for 3 months. They found, that patients treated with the supplementation were more likely to maintain their intestinal permeability, whereas this deteriorated in the placebo group.
Increased intestinal permeability is considered a measure of gut leakiness, which is shown to predict and precede clinical relapse in CD. In addition, patients with the highest blood levels of vitamin D had signs of reduced inflammation (measured by C-reactive protein and antimicrobial peptides), and these patients also reported better quality of life.