I can't speak to the Houston region in specific, but from what I've read here, it appears that many (though not all) who take LDN usually get it through a different source than the GI -- a primary care physician, naturopath, etc. I had a GI that was willing to prescribe to me, but only because I came armed with some published studies for evidence, and I was doing "OK" by their standards -- I wasn't a severe case. LDN isn't considered standard-of-care yet, so finding a gastroenterologist to prescribe it might be tricky.