Omega-3 fatty acid supplements are made from either fish oils or from plant sources such as flaxseed oil, but there are some structural differences between the fats found in animals and the fats found in plants. Fish oil contains two long-chain fatty acids called docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), which are the forms of omega-3s that your body uses for a variety of purposes. Flax and other plant oils contain alpha-linolenic acid (ALA), which is also an omega-3 fatty acid, but it has a slightly different structure compared to EPA and DHA. Your body should be able to convert the ALA to either DHA or EPA depending upon which fatty acid your body needs. Here's more about fat structure and function in your body.
Algal oil, which is made from ocean algae, is the one plant source of omega-3 fatty acids that contains pre-formed DHA. Algal oil is also sold as a dietary supplement.
Both fish oil and plant-based omega-3 fatty acid supplements are safe to take as long as you follow the label directions. Taking these supplements for long periods of time may lead to vitamin E deficiencies in some people, and taking large amounts of omega-3 supplements may interfere with blood clotting or interact with certain medications. Speak with your health care provider before taking large amounts of any dietary supplements.
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