i've got IBS-D and started taking Primal Defense probiotics about 3+ years ago. For the most part, it works for me every day, until i get a major relapse, then i have to bring out the big guns: psyllium + bentonite clay + caproil (taken away from probiotics) AND stop all sugar and caffeine. i also have to re-examine what i'm eating/drinking/doing in my life and figure out what i need to do (which is where i'm at again) -but for me, the 1 Primal Defense probiotic is essential on a daily basis.