Billie, I dont know how the caltrate works, I wonder about that myself, the only thing I can think why it works is that vitamins are constipating. As for fiber, it adds bulk to your stools. Citrucel or metamucil acts likes a gel and absorb all the water and make your stools firmer. But make sure you drink alot of water otherwise you will have rocks in there and nothing will pass around it. Add other form of fiber too, like vege, fruit with the skin on, bran, wheat, beans, they do the same things and more pleasant to eat than to drink your food. But a supplement is still a good way to add fiber but it might also give you gas but as your body adjust it will pass. Hope this answer your question.