Flaxseed Oil vs Fish Oil

by John Staughton (BASc, BFA) last updated -

The debate of flaxseed oil vs fish oil continues to rage in nutrition circles, and there are some clear differences that separate the two.

Flaxseed Oil vs Fish Oil

Both flaxseed oil and fish oil are popular supplements, but what are the key differences between the two? And can they really help in your overall health?

What is Flaxseed Oil and Fish Oil?

  • Also known as linseed oil, flaxseed oil is a yellowish oil made from dried flaxseeds.
  • Fish oil is made from the tissue of oily fish, such as mackerel, salmon, and cod.
A picture of a bowl of flaxseed oil next to a picture of fish oil capsules in a fish-shaped dish

Flaxseed oil vs fish oil Photo Credit: Shutterstock


  • Flaxseed oil is non-toxic but some industrial flax oil cleaners, labeled as linseed oil, contain toxic cleaning agents. So it’s important to always buy food-grade flaxseed oil. [1]
  • Fish oil is non-toxic, but certain fish, such as tuna, may contain high levels of mercury, which can be toxic over time. Be sure to identify where your fish oil comes from and only buy from reputable vendors.


Both oils are good sources of omega-3 fatty acids but contain different types of this critical nutrient. Omega-3 fats are particularly recommended for bodybuilders, as they help build muscle and aid muscle recovery. [2]

  • Flaxseed oil contains plant-based omega-3 fatty acid known as alpha-linolenic acid (ALA), which helps with weight loss and heart health, in addition to lowering cholesterol. [3]
  • Fish oil contains omega-3 fatty acids – eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). DHA is an essential fatty acid required for the development of the fetus during pregnancy. It also helps with dry eyes and encourages hair growth. EPA is most effective at reducing inflammation. [4]

Side Effects 

  • Taking fish oil can reduce your body’s ability to absorb vitamin E.
  • Large doses of either oil can lead to loose stool or diarrhea.
  • Possible allergic reactions may occur in some people.

Which is Better?

  • Both oils contain essential omega-3 fatty acids.
  • Many people believe that fish oil is a more direct way to obtain both essential fatty acids.
  • Flaxseed oil contains only the ALA variety of omega-3, this actually converts to DHA and EPA in your system, although in much smaller amounts than what is available in fish oil.
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About the Author

John Staughton is a traveling writer, editor, publisher and photographer with English and Integrative Biology degrees from the University of Illinois in Champaign-Urbana (USA). He co-founded the literary journal, Sheriff Nottingham, and now serves as the Content Director for Stain’d Arts, a non-profit based in Denver, Colorado. On a perpetual journey towards the idea of home, he uses words to educate, inspire, uplift and evolve.

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