Because the advantages of feeding fat are accepted almost universally by equine nutritionists, veterinarians, and horsemen, scientists are delving deeper into how certain fats help horses. Researchers have focused much of their attention on omega-3 fatty acids and the relationship between them and omega-6 fatty acids. The two types of fatty acids must be balanced within the body in order for both to be effective. Horses are often fed diets composed entirely of grain mixes and hay. Such diets are rich in omega-6 fatty acids but extremely low in omega-3 fatty acids. If vegetable oil is added to the ration, it further skews the ratio, with omega-6 fatty acids being overrepresented. To help counteract this imbalance, horses should be supplemented with omega-3 fatty acids, the richest sources of which are fish oils.