Omega-3 fats are acquired from both animal and plant sources, but there is a lot of confusion when it comes to what type you should take to get the best omega-3 benefits.
Marine animals such as fish and krill provide eicosapentaenoic acid (EPA) anddocosahexaenoic acid (DHA), which are mostly promoted for their protective effects on your heart. Flaxseed, chia, hemp, and a few other foods, on the other hand, offer alpha-linoleic acid (ALA). 2
You would want to choose an animal-based variety – most of the health benefits linked to omega-3 fats are linked to the animal-based EPA and DHA, not the plant-based ALA.
Furthermore, ALA is converted into EPA and DHA in your body at a very low ratio. What this means is that even if you consume large amounts of ALA, your body can only convert a relatively small amount into EPA and DHA, and only when there are sufficient enzymes.
Remember, though, that plant-based omega-3 fats are NOT inherently harmful or should be avoided. Ideally, what you want to do is include an animal-based form in your diet. For instance, you can combine flax and hemp in your diet with animal-based omega-3s.