The availability and necessity of vitamin E in equine diets is well established. When healthy horses are given frequent access to fresh green forage such as good-quality pasture, there is little need for supplementation of vitamin E. However, many horses today are managed without fresh forage in their diets. These horses can survive in such management systems, but they will likely not be consuming sufficient vitamin E for optimal health.

Vitamin E is first and foremost an antioxidant, an agent that keeps free radicals from forming and potentially weakening cells and tissues. In addition to its antioxidant responsibilities, vitamin E is vital to immune, cardiovascular, circulatory, neuromuscular, and reproductive functions. Therefore, supplementation with an effective vitamin E supplement is recommended for all horses that do not consume a significant quantity of green pasture.