Omega-3 essential fatty acids can be divided into two categories: plant sources (linseed oil, containing ALA), or marine sources (fish oil, containing EPA and DHA).
Humans convert ALA to EPA and DHA at a slower rate and which may be affected by many factors. For example, too much Omega-6 or trans fatty acids from the diet of fast food and baked goods, alcohol, some specific health conditions or lack of vitamins and minerals (vitamins B3, B6, zinc, magnesium, etc.). According to clinical studies, the ability of humans to convert ALA to EPA is only about 15%, and most people are not even able to convert ALA to DHA. Linseed oil is a healthy oil that can also bring many benefits to the human body; however, it is not a good source of EPA and DHA. On the contrary, marine sources such as fish oil and algae oil contain the kind of EPA and DHA that can be directly absorbed by human body.