@Bansaw, I tried L-glutamine (150mg a day) but had to abandon it after 2 days as it made me extremely and unbearably aggressive and irritable. I have trouble tolerating some meds and supplements and this one is definately not for me.
I have had success with gluten, dairy, soy free diet, eliminating other identified problem foods, FODMAPs diet and supplementing with apple pectin, slippery elm, curcumin and probiotics.
Has made a big difference for me. IBS symptoms largely resolved and regained much needed weight.
Best wishes, Andy