How do you know if something, anything from a car to a blender to a vitamin supplement, works? You test it in a manner consistent with the way it’s going to be used, using specific, relevant measures of performance, and evaluate it according to those parameters.

Unfortunately, many equine nutritional and performance-enhancing supplements did not undergo such testing and evaluation before being put on the market. It’s not legally required that they be proven effective. If there is valid research on a product, you have to interpret the results to see if it did work and if the results can be extrapolated to your horse’s situation