Best Omega-3 Supplement: Flaxseed Oil vs. Fish Oil

The best omega-3 supplement must be one that can optimize your body’s levels of EPA and DHA. Can a vegetarian omega-3 do this? Let’s clear the confusion by looking at plant-based omega-3 oils (such as evening primrose and flaxseed oil) and then comparing them to fish oil.

best omega-3 supplement

Which is the best omega-3 supplement?The flaxseed oil vs. fish oil debate has been going on for years.

Have you heard the claim that the best omega-3 supplement is a vegetarian omega-3? The fish oil vs. flaxseed oil debate has been going on for years but recently came to the forefront again. Some well-known natural health experts say that it’s better to get your long-chain omega-3 fatty acids (EPA, or eicosapentaenoic acid, and DHA, or docosahexaenoic acid) from the conversion of flax and other plant-based omega-3 oils. Other experts claim this is inaccurate and state that it’s best to take a direct source of EPA and DHA from fish or algae.

In this article, we examine the evidence in looking for the best omega-3 supplement.

Deciphering the Three Best Omega-3 Supplements

There are three major types of omega-3 fatty acids that are ingested in foods and used by the body:

  • Alpha-linolenic acid (ALA)
  • Eicosapentaenoic acid (EPA)
  • Docosahexaenoic acid (DHA)

Most of the ALA consumed in the diet comes from plant sources such as flaxseed and other nuts and seeds. Once eaten, the body uses certain vitamins, minerals, and genetically controlled enzymes to convert ALA to EPA and then to DHA.

EPA and DHA can also be consumed directly. The highest concentrations of EPA and DHA are found in cold-water fish such as salmon, tuna, and herring. EPA and DHA are the two types of omega-3 fatty acids that serve important roles in cell signaling, gene expression, inflammatory processes, and other bodily processes fundamental to health. In other words, it is EPA and DHA, rather than ALA, that perform essential functions in the body.

Are Plant-Based Omega-3s Better?

One popular claim is that your body will automatically convert other omega-3 oils into exactly the amount of EPA and DHA it needs, as long as you provide it with enough omega-3 oils along with the proper vitamins required to assist in the synthesis. One of the important vitamins needed for EPA and DHA synthesis is vitamin B6. If people just consumed adequate vitamin B6, they would efficiently convert the ALA from other omega-3 oils into EPA and DHA and they wouldn’t need to take fish oil, so the claim goes.

But the truth is that conversion of ALA from other omega-3 oils into EPA and DHA is dependent on much more than vitamin B6. Niacin, vitamin C, zinc, and magnesium are needed for the conversion, too.

But that’s only a small part of the story. In fact, scientists still don’t have the full conversion picture totally figured out. However, they have discovered that genetics, age, gender, and—perhaps most important—the other fats in your diet all play important roles in how much EPA and DHA can be synthesized.

Consider these factors, all of which iInfluence your body’s ability to convert ALA to EPA and DHA:

  • Other dietary fats. Vegetable oils high in omega-6 fatty acids, such as canola oil, compete for the same compounds that ALA from flax oil needs to convert to EPA and DHA, and the omega-6s win out. Not only that, but omega-6s also inhibit the incorporation of DHA and EPA into your body’s tissues. So the more omega-6 oils you consume, the less EPA and DHA you can make from flax, and even what you can make is blocked from being utilized.[1]
  • Gender. Human studies show that males and females differ in their ability to synthesize EPA and DHA from ALA. In particular, women have a higher capacity than men to synthesize DHA from ALA. The studies suggest that estrogen stimulates, whereas testosterone inhibits, the conversion. Thus, women consistently have higher DHA levels than men.[2]
  • Age. How old you are appears to make a difference in how well you can synthesize DHA, in particular, from ALA. In recent animal studies, researchers found that the older rats get, the less DHA they can synthesize. Since DHA is the fatty acid incorporated into the brain, researchers believe “its reduced synthesis may be deleterious to brain function.”[3]
  • Genetics. Genetic variability in the genes that control the synthesis of the long-chain omega-3’s EPA and DHA is common. Certain variations of these genes have been found to be directly associated with people’s EPA and DHA levels. It wasn’t until quite recently that researchers discovered just how important these tiny variations in genes can be to EPA and DHA synthesis.[4]

Algae or Fish Oil is the Best Omega-3 Supplement

In summary, the question of what the best omega-3 supplement is should be put to rest. Although ALA can be used for EPA and DHA synthesis, studies have found that this pathway is limited in humans and varies between individuals based on genes, sex, age, and intake of other fats and nutrients.

So far, no human studies have shown that intake of vegetarian omega-3 sources (ALA) plus certain vitamins, like vitamin B6, leads to optimal levels of EPA and DHA inside the body’s cells and tissues. Therefore, direct dietary intake of omega-3 fats rich in EPA and DHA through food or supplements is the most beneficial.

So What’s an Optimal Fish Oil Dose?

If you haven’t started increasing your direct intake of EPA and DHA through foods like clean cold-water fish or EPA/DHA supplements from fish or algae, now is the time to start. For health maintenance, take at least 1,000 mg of EPA and DHA per day or eat a serving of oily fish at least twice a week. A therapeutic dose for treatment of inflammatory-related conditions, including atherosclerosis and high triglycerides, is 3,000 to 4,000 mg of EPA and DHA per day.

To learn more about choosing the best omega-3 supplement, see the following posts:

[1] Matern Child Nutr. 2011 Apr;7Suppl 2:17-26.

[2] Ann NutrMetab 2013;62:98–112.

[3] Age (Dordr). 2013 Jun;35(3):597-608.

[4] Am J ClinNutr. 2013 Jan;97(1):195-207.

Originally published in 2013 and regularly updated.

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  • I have a shell fish allergy and have had an allergic reaction to flax seed oil. is there another source for the Omega 3 fish oil?

  • How about plain.ole flax seed? You have to grind it up first. Everything is better in its unprocessed natural.form. The article doesn’t take into account people on whole food plantbased diets get all the vitamins and minerals (exc. B-12). Supplements have no fda standards for quality and I have read you cannot know how old the supplements are; oils spoil. Also.Diets high in animal.protein (SAD, standard American diet) have a higher rate of cancer, diabetes, heart disease than plantbased vegan . So although fish oil in itself is “better”, cumulatively, not so much.

  • Frances Please look at the Omega Blend by Juice Plus. It just became available to the public in Oct 2017. It is totally vegan. You can find it at Please email me at and I can answer any questions you may have. Good Luck!

  • I just started getting your newsletter. I thank you for the very helpful and pertinent health topics and article. Please don’t stop publishing them.

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