I tried Optimum Digestive Health following some colic issues a couple of years ago that were tough to resolve. My vet recommended another product she had first-hand experience with but it was too expensive. After researching, I discovered this product had the same effective ingredients without the fillers and sugars of the more expensive product. The colic episodes disappeared after about 6 weeks. I tested it last summer by removing the Optimum for a couple of months but my horse began acting like he was uncomfortable again so I put him back on it. We're now at a point where he is okay without it in the summer, but I'll be adding it back in over the winter just to be safe.