When looking to supplement your horses diet, whether it be a basic vitamin, mineral supplement, or something more specific such a joint or hoof supplement there are few things to consider before deciding which one is best for your horse.
One of the most important things is to learn to read the labels. Don't just read the guaranteed analysis. Read the actual ingredients list. What you don't want to see is the addition of too many fillers, artificial flavors, sweeteners and other chemical names that you can't even pronounce!
Here is a list of things that you do not want to see in the supplement or feed:
Mineral Oil (this is a petroleum by product)
Sugar, includes molasses, cane, liquid
Artificial sweeteners such as sucralose, saccharin, sorbitol, aspartame, acesulfame K, dextrose
Grain by products
Synthetic Vitamin E: dl-alpha-tocopheryl acetate
(natural Vitamin e will not have the l after the d)
These things are cheap ingredients for the manufacturer and are often used as fillers to make the product more appealing. None of these ingredients are desirable in your horses diet. Better quality supplements will not have any of these ingredients, therefore producing better results without side effects from unwanted chemicals.