I've had IBS-D for 40 years. Tried every tablet, every exclusion diet, had every test, taken every supplement, without much success. BUT a couple of years ago I went on the 'Dukan Diet' to lose some weight. This starts off by only having protein foods for a few days, then alternating one day only protein, next day protein with veggies. No fruit, fat or sugar. Miracles occurred! I believe that the problem causing IBS-D is the wrong type of bacteria in the gut. If you avoid the foods they thrive on for a while, (Starches and sugars) they die and leave you with the good guys. My IBS was miles better for two years but then started to slowly get worse again. So, this summer I've gone back to the Dukan Diet for two months and Lo and Behold, my IBS is much, much better again. I REALLY recommend trying this, it can change your life.