A lot of people swear by Glucosamine (and Chondroitin) for cartlidge repair, but ITBS is not cartlidge, so..........not sure if you have other problems aswell?
I think stretching is essential to cure the ITBS, and if inflexibilty alone is the problem, stretching alone may be all that is required. However, from what I have picked up from these forums (fora?) and elsewhere, there is often an underlying biomechanical problem causing the ITBS, which would need to be corrected somehow.