Benefits of Fish Oil as a Source of Omega-3s
Fish oil primarily contains eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and consuming it provides your body with a healthy booster of these fatty acids without requiring any metabolic effort. However, consuming ground flaxseed rich in ALA, or flaxseed oil offers significant additional health benefits to consuming fish oil alone The ALA out-competes dietary LA for enzymes needed to convert ALA into other omega-3s such as EPA and DHA (Domenichiello 2016). By giving your body the necessary ingredients to trigger this chain reaction (ALA that can be converted to EPA and DHA) you can prevent your body from converting some of the excess omega-6 fatty acids in your diet into the substitute and potentially harmful fatty acids that can contribute to disease onset.
Consuming omega-3s in fish oil form alone will not reduce the number of inflammatory products your body produces from the high levels of omega-6 in your diet. Also, fish oil can contain heavy metal contaminants such as mercury. If most of your fish oil intake is consumed as a supplement, the source of that oil and how it is refined will determine if it contains heavy metals. For example, fish oil sourced from salmon (top of the food chain) has a greater potential to contain heavy metals than fish oil sourced from krill (bottom of the food chain).
If you are consuming fish oil primarily by adding fish to your diet, you are undoubtedly exposing yourself to higher burdens of heavy metals such as mercury, because you are consuming unrefined oil. Heavy metal contamination is not a concern for flaxseed sourced from Canadian growers.