There are three primary omega-3s: ALA, EPA, and DHA. While they are all considered healthful fats, there are big differences between the three and the function they perform in the body. ALA (alpha-linoleic acid) offers limited health benefits. EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) have been studied the most and have many vital, life-sustaining roles.